CN116381278A - Atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method - Google Patents
Atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method Download PDFInfo
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Abstract
The invention discloses an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method, which relate to the technical field of infrared spectrums, wherein a beam combining lens is used for combining infrared laser and visible laser, so that the infrared laser and the visible laser are collinear to obtain collinear laser, an incidence adjusting component is used for enabling the collinear laser to vertically pass through an incidence side surface of a triple prism to be focused on a sample side surface, a focus of the collinear laser is positioned under a needle point to complete the spatial position coupling of the collinear laser and an atomic force microscope probe, a processor is used for processing a micro-cantilever deflection signal generated by the atomic force microscope and a reflected laser intensity signal generated by a photo-thermal detector, and simultaneously obtaining the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum, so that the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum can be synchronously acquired, and the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum can be acquired simultaneously and in situ.
Description
Technical Field
The invention relates to the technical field of infrared spectrums, in particular to an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method.
Background
The infrared spectrum technology utilizes the absorption of infrared light by the sample, and can detect the characteristic functional groups in the sample. When the wavelength of infrared light is in the mid-infrared band range, the frequency of the infrared light can be coupled with stretching and bending vibration of covalent bonds in the sample molecules, so that the infrared spectrum technology has stronger analysis capability on the internal structure of the sample.
Infrared spectroscopy techniques include total internal reflection infrared spectroscopy techniques and atomic force microscopy infrared spectroscopy techniques. The total internal reflection infrared spectrum technology is characterized in that a sample is fixed on the surface of an infrared transparent material, the incident angle is adjusted, so that the infrared laser is subjected to total internal reflection at the interface of the infrared transparent material and air, the characteristic functional groups of sample molecules are excited by using an evanescent field generated by total internal reflection, the laser after total internal reflection is collected and compared with the background intensity of the original laser, and the total internal reflection infrared spectrum of the sample can be obtained. In recent years, an atomic force microscope infrared spectrum technology has been developed, and the technology irradiates a beam of modulated infrared laser onto the surface of a sample of an atomic force microscope by constructing an infrared laser path, and realizes the coupling of an atomic force microscope probe and the infrared laser by the induction of visible laser so as to obtain the atomic force microscope infrared spectrum. The atomic force microscope infrared spectroscopy technology uses an atomic force microscope probe as a spectrum detector, breaks through the diffraction limit of infrared imaging, improves the resolution of infrared imaging from micron level to nanometer level, and has two modes of upper incidence and lower incidence, wherein the upper incidence mode can be combined with a gold-plated atomic force microscope probe and a gold-plated sample substrate to realize the enhancement of the atomic force microscope infrared spectrum so as to achieve higher signal to noise ratio; the lower incidence mode excites the sample by the evanescent field generated by the infrared laser when total internal reflection occurs at the infrared transparent material-air interface, typically using a gold-plated atomic force microscope probe to improve the signal-to-noise ratio.
For total internal reflection infrared spectroscopy, the infrared imaging resolution is limited to the micron order due to the longer wavelength of the infrared laser (typically 5-15 microns), which is affected by the diffraction limit. Aiming at the defects, the atomic force microscope infrared spectrum technology realizes the nanoscale infrared imaging of the sample, and improves the infrared imaging resolution by two orders of magnitude. However, since the atomic force microscope infrared spectroscopy technology uses an atomic force microscope probe as a detector of infrared laser, the detection principle of the atomic force microscope probe is highly dependent on the thermal expansion coefficient of a sample, so that the total internal reflection infrared spectroscopy of the sample is required as a contrast to ensure the reliability of the acquired atomic force microscope infrared spectroscopy. However, in the actual process, it is difficult to realize simultaneous and in-situ (in-situ) acquisition of the total internal reflection infrared spectrum and the atomic force microscope infrared spectrum, and finally, the synchronism of the two infrared spectrums is difficult to be ensured.
Disclosure of Invention
The invention aims to provide an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method, which can synchronously acquire the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum and realize the simultaneous and in-situ acquisition of the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum.
In order to achieve the above object, the present invention provides the following solutions:
an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device comprises an infrared laser light source, a visible laser light source, a beam combining mirror, an incidence adjusting component, a triple prism, an atomic force microscope, a photo-thermal detector and a processor; a sample is placed on the sample side surface of the triangular prism; the tip of an atomic force microscope probe of the atomic force microscope is contacted with the sample;
the beam combining lens is used for combining infrared laser emitted by the infrared laser source and visible laser emitted by the visible laser source to make the infrared laser and the visible laser collinear to obtain collinear laser, and the collinear laser is incident to the incidence adjusting component; the collinear laser comprises the infrared laser and the visible laser;
the incidence adjusting component is used for reflecting the collinear laser, enabling the collinear laser to vertically pass through the incidence side surface of the triangular prism and focus on the side surface of the sample, and enabling the focus of the collinear laser to be located right below the needle point;
the atomic force microscope is used for generating a micro-cantilever deflection signal of the micro-cantilever of the atomic force microscope probe after the collinear laser is focused on the side surface of the sample; the micro-cantilever deflection signal is a change curve of deflection of the micro-cantilever along with time;
The photo-thermal detector is used for receiving reflected laser emitted from the emergent side surface of the triangular prism and generating a reflected laser intensity signal; the reflected laser is generated after the collinear laser generates total internal reflection on the side surface of the sample; the reflected laser intensity signal is a change curve of the laser intensity of the reflected laser along with time;
the processor is respectively in communication connection with the atomic force microscope and the photo-thermal detector; the processor is used for processing the micro-cantilever deflection signal and the reflected laser intensity signal to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum.
In some embodiments, the synchronization acquiring device further comprises: the device comprises a first reflecting mirror, a first iris diaphragm, a turnover assembly and a second iris diaphragm;
the first reflecting mirror is positioned between the infrared laser light source and the beam combining mirror; the first reflecting mirror is used for reflecting the infrared laser to the beam combining mirror;
the beam combining lens is used for combining the infrared laser and the visible laser to obtain combined laser, and the combined laser is incident to the first iris diaphragm;
the apertures of the first iris diaphragm and the second iris diaphragm are in a minimum state; the first iris diaphragm is used for transmitting the combined laser to the turnover assembly;
The overturning assembly is used for reflecting the combined laser to the second iris diaphragm;
the second iris diaphragm is used for transmitting the combined laser to the photo-thermal detector;
the photo-thermal detector is used for receiving the combined laser and determining a first power of infrared laser and a second power of visible laser in the combined laser;
the processor is configured to adjust the position and angle of the first mirror based on the first power and the second power until the first power and the second power both reach a maximum value.
In some embodiments, the flip assembly includes a flip frame and a second mirror mounted on the flip frame; the processor is in control connection with the overturning frame; when the position and the angle of the first reflecting mirror need to be adjusted, controlling the turnover mirror frame to be in an open state, so that the combined laser is reflected to the second iris diaphragm; when the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum are required to be obtained, the turnover frame is controlled to be in a closed state, so that the collinear laser is incident to the incidence adjusting component.
In some embodiments, the incidence adjustment assembly comprises a three-axis displacement stage and an off-axis parabolic mirror mounted on the three-axis displacement stage; the off-axis parabolic mirror is used for reflecting the collinear laser;
The processor is in control connection with the triaxial displacement table; the processor is used for controlling the movement of the triaxial displacement table so that the collinear laser is focused on the side surface of the sample vertically through the incidence side surface after being reflected by the off-axis parabolic mirror, and the focus of the collinear laser is positioned right below the needle point.
In some embodiments, the sample has gold nanoparticles on the sides; the gold nanoparticles are obtained by in-situ growth after the aqueous solution of chloroauric acid is dripped on the side surface of the sample.
In some embodiments, the angle between the sample side and the entrance side is the same as the angle between the sample side and the exit side.
In some embodiments, the synchronization acquiring device further comprises a plurality of third mirrors positioned between the first iris and the flip assembly, which are sequentially connected in optical path.
An atomic force microscope-total internal reflection infrared spectrum synchronous acquisition method for controlling the synchronous acquisition device to work, the synchronous acquisition method comprises the following steps:
acquiring a micro-cantilever deflection signal generated by an atomic force microscope and a reflected laser intensity signal generated by a photo-thermal detector; the micro-cantilever deflection signal is a change curve of deflection of the micro-cantilever along with time; the reflected laser intensity signal is a change curve of the laser intensity of the reflected laser along with time;
Respectively processing the micro-cantilever deflection signal and the reflected laser intensity signal by using a background signal of an infrared laser light source to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum; the background signal is a curve of the laser intensity of the infrared laser along with the wave number.
In some embodiments, the processing the micro-cantilever deflection signal and the reflected laser intensity signal by using the background signal of the infrared laser light source to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum specifically includes:
demodulating the micro-cantilever deflection signal by using a reference signal to obtain a micro-cantilever amplitude signal; the reference signal is a signal which is generated by the infrared laser light source and has the same frequency as the pulse repetition frequency of the infrared laser light source; the micro-cantilever amplitude signal is a change curve of the amplitude of the micro-cantilever along with time;
converting the micro-cantilever amplitude signal into a micro-cantilever amplitude wave number signal; the micro-cantilever amplitude wave number signal is a change curve of the amplitude of the micro-cantilever along with the wave number;
dividing the micro-cantilever amplitude wave number signal by the background signal to obtain an atomic force microscope infrared spectrum;
Converting the reflected laser intensity signal into a reflected laser intensity wavenumber signal; the reflected laser intensity wave number signal is a change curve of laser intensity of the reflected laser along with wave number;
dividing the reflected laser intensity wave number signal by the background signal to obtain a total internal reflection infrared spectrum.
In some embodiments, the method for determining the pulse repetition frequency of the infrared laser light source includes:
under the condition of no infrared laser irradiation on a sample, acquiring a micro-cantilever deflection background signal generated by an atomic force microscope; performing FFT conversion on the micro-cantilever deflection background signal to obtain the resonance frequency of the atomic force microscope probe and the sample; the resonance frequency is set to a pulse repetition frequency of the infrared laser light source.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention provides an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method, wherein a beam combining lens is used for combining infrared laser and visible laser to enable the infrared laser and the visible laser to be collinear, the collinear laser is obtained, an incidence adjusting component is used for reflecting the collinear laser, the collinear laser is vertically focused on a sample side surface through an incidence side surface of a triple prism, a focus of the collinear laser is positioned under a needle point to complete space position coupling of the collinear laser and an atomic force microscope probe, the atomic force microscope generates a micro-cantilever deflection signal of a micro-cantilever of the atomic force microscope probe, a photo-thermal detector is used for receiving reflected laser emitted through an emergent side surface of the triple prism to generate a reflected laser intensity signal, and a processor is used for processing the micro-cantilever deflection signal and the reflected laser intensity signal to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum simultaneously, so that the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum can be synchronously acquired at the same time.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of an optical path structure of a synchronous acquisition device according to embodiment 1 of the present invention when the synchronous acquisition device is used for synchronously acquiring two infrared spectrums;
fig. 2 is a schematic diagram of an optical path of a beam combiner according to embodiment 1 of the present invention;
fig. 3 is a schematic diagram of an optical path structure of the synchronization acquiring device according to embodiment 1 of the present invention when the synchronization acquiring device is used for adjusting a collinear state;
fig. 4 is a flowchart of a method for acquiring synchronization according to embodiment 2 of the present invention;
fig. 5 is a schematic diagram of a signal transmission path of the synchronization acquiring device according to embodiment 2 of the present invention;
fig. 6 is a schematic diagram of a data processing flow of the synchronization acquiring device according to embodiment 2 of the present invention;
FIG. 7 is a graph showing the comparison of the micro-cantilever amplitude wave number signal and the background signal of the spin-coated polystyrene ultra-thin film according to example 2 of the present invention;
FIG. 8 is a schematic diagram of an atomic force microscope infrared spectrum of a spin-coated polystyrene ultra-thin film according to example 2 of the present invention;
FIG. 9 is a graph showing the comparison of reflected laser intensity wave number signal and background signal of the spin-coated polystyrene ultra-thin film provided in example 2 of the present invention;
FIG. 10 is a graph showing the total internal reflection IR spectrum of the spin-on polystyrene ultra-thin film according to example 2 of the present invention;
FIG. 11 is a schematic diagram of an atomic force microscope-total internal reflection combined infrared spectrum of a spin-coated polystyrene ultra-thin film provided in example 2 of the present invention;
FIG. 12 is a graph showing the comparison of the micro-cantilever amplitude wave number signal and the background signal of the spin-coated polyvinyl cinnamate film according to example 2 of the present invention;
FIG. 13 is a schematic diagram of an atomic force microscope IR spectrum of a spin-on polyvinyl alcohol cinnamate film according to example 2 of the invention;
FIG. 14 is a graph showing the comparison of reflected laser intensity wavenumber signal and background signal for a spin-coated polyvinyl alcohol cinnamate film provided in example 2 of the invention;
FIG. 15 is a graph showing the total internal reflection IR spectrum of the spin-on polyvinyl alcohol cinnamate film according to example 2 of the invention;
FIG. 16 is a schematic diagram showing the comparison of the IR spectra of an atomic force microscope before and after UV treatment of a spin-coated polyvinyl alcohol cinnamate film according to example 2 of the present invention;
Fig. 17 is a nanoinfrared imaging of a cast polystyrene-polymethyl methacrylate blend film provided in example 2 of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device and method, which can synchronously acquire the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum and realize the simultaneous and in-situ acquisition of the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Example 1:
the embodiment is used for providing an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device, as shown in fig. 1, wherein the synchronous acquisition device comprises an infrared laser light source (also can be called an infrared laser or an electro-optical modulator), a visible laser light source, a beam combining mirror, an incidence adjusting component, a triple prism, an atomic force microscope, a photo-thermal detector and a processor.
Because infrared laser cannot be observed by naked eyes, the infrared laser and the atomic force microscope probe cannot be directly coupled in space through the optical microscope, visible laser which can be observed by naked eyes is further introduced into the embodiment and used as guide laser, the visible laser and the infrared laser are firstly adjusted to be in a collinear state, then whether the visible laser and the atomic force microscope probe realize the coupling in space or not is observed, and when the visible laser and the atomic force microscope probe realize the coupling in space, the infrared laser and the atomic force microscope probe also finish the coupling in space.
In order to achieve the above object, the present embodiment is provided with both an infrared laser light source for emitting infrared laser light and a visible laser light source for emitting visible laser light. Alternatively, in this embodiment, a quantum cascade laser is used as the infrared laser light source, a photodiode is used as the visible laser light source, the solid line in fig. 1 is an infrared laser transmission path, and the broken line is a visible laser transmission path. In addition, in order to adjust two beams of laser (i.e., infrared laser and visible laser) to a collinear state, the embodiment introduces a beam combining lens, the beam combining lens can adopt a zinc selenide window sheet with a surface coated with a film, the schematic light path of the beam combining lens is shown in fig. 2, the beam combining lens is inclined 45 degrees relative to the horizontal plane, one side surface of the beam combining lens is coated with a reflecting film, the side surface coated with the reflecting film is called a reflecting surface, the other side surface of the beam combining lens is coated with a transmitting film, the side surface coated with the transmitting film is called a transmitting surface, infrared laser emitted by an infrared laser source irradiates the transmitting surface, visible laser emitted by a visible laser source irradiates the reflecting surface, the total transmission of 5-12 mu m of infrared laser incident at 45 degrees can be realized through the beam combining lens, and meanwhile, the total reflection of 635nm of visible laser incident at 45 degrees can be realized through the beam combining lens, and the beam combining laser can be carried out. However, if the infrared laser passing through the beam combining lens is required to be collinear with the visible laser, the incident position of the infrared laser on the beam combining lens needs to be further adjusted, and the infrared laser passing through the beam combining lens and the visible laser are collinear through adjustment of the incident position, so that the collinear laser is obtained.
According to the embodiment, the collinear state of the infrared laser and the visible laser is determined by introducing the two diaphragms after the beam combining lens, namely, if the two diaphragms are closed to the minimum state at the same time (specifically, the apertures of the two diaphragms are in the minimum state, and the light spots of the infrared laser and the visible laser are larger than the aperture in the minimum state at the moment), the photo-thermal detector can still detect the maximum infrared laser power and the maximum visible laser power, and the fact that the centers of the two lasers (namely, the infrared laser and the visible laser) after passing through the beam combining lens pass through the centers of the two diaphragms is proved, and at the moment, the collineation of the infrared laser and the visible laser can be realized through the beam combining lens, namely, the infrared laser and the visible laser are in the collinear state after passing through the beam combining lens. Based on this concept, in the present embodiment, when designing the synchronous acquisition device, considering that the manner of adjusting the incident position of the infrared laser on the beam combining mirror by moving the infrared laser light source is difficult to achieve, a plurality of first mirrors are provided between the infrared laser light source and the beam combining mirror, the incident position of the infrared laser on the beam combining mirror is adjusted by adjusting the positions and angles of the first mirrors, and simultaneously, in order to synchronously acquire the infrared spectrum and the total internal reflection infrared spectrum of the atomic force microscope, which are the final purpose of the synchronous acquisition device, it is necessary to introduce the infrared laser and the visible laser onto the sample, and when judging the collinear state, it is necessary to introduce the infrared laser and the visible laser onto the photo-thermal detector, so the present embodiment is provided with a flipping assembly, and the optical paths of the infrared laser and the visible laser after being co-beam-combined by the beam combining mirror are controlled by the flipping assembly to irradiate the photo-thermal detector or the sample.
Based on this, in order to implement the above-mentioned adjustment process of the collinear state, as shown in fig. 3, the synchronization acquiring device of the present embodiment includes a first reflecting mirror, a first iris, a flipping component, and a second iris, where the first reflecting mirror is located between the infrared laser light source and the beam combining mirror, and the first reflecting mirror is used for reflecting the infrared laser light to the beam combining mirror. In this embodiment, the first mirrors may be one or more, and fig. 3 illustrates a case of including two first mirrors, at this time, the infrared laser emitted by the infrared laser source is reflected by the first mirrors onto the second first mirrors, the second first mirrors reflect the infrared laser onto the beam combining mirror, the visible laser emitted by the visible laser source is directly incident onto the beam combining mirror, and the beam combining mirror combines the infrared laser and the visible laser to obtain the combined laser. The first iris diaphragm, the turnover assembly and the second iris diaphragm are sequentially arranged on an optical path from the beam combination laser to the photo-thermal detector, and the apertures of the first iris diaphragm and the second iris diaphragm are in a minimum state. The beam combining lens is used for making the combined laser incident to the first iris diaphragm, and the first iris diaphragm is used for transmitting the combined laser to the overturning assembly. In the adjustment process of the collinear state, the overturning assembly is in an open state, and the overturning assembly is used for reflecting the combined laser to the second iris diaphragm. The second iris is used for transmitting the combined laser light to the photo-thermal detector. The photo-thermal detector is used for receiving the combined laser light and determining a first power of infrared laser light and a second power of visible laser light in the combined laser light. The processor is used for adjusting the position and the angle of the first reflecting mirror according to the first power and the second power until the first power and the second power reach the maximum value, the position and the angle of the first reflecting mirror can be manually adjusted, and a driving component (such as piezoelectric ceramics) can be arranged on the first reflecting mirror, so that the position and the angle of the first reflecting mirror can be automatically adjusted by controlling the driving component. When the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum are obtained subsequently, the position and the angle of the first reflecting mirror are kept at the position and the angle of the first reflecting mirror when the first power and the second power reach the maximum value, at the moment, when infrared laser emitted by the infrared laser source is incident to the beam combining mirror through the first reflecting mirror, the beam combining mirror can combine the infrared laser and the visible laser, so that the infrared laser and the visible laser are collinear, and collinear laser is obtained.
The tilting assembly of this embodiment may include a tilting frame and a second mirror mounted on the tilting frame, the processor being in control connection with the tilting frame. When the position and the angle of the first reflecting mirror need to be adjusted, namely infrared laser and visible laser need to be made to enter the photo-thermal detector, the turnover mirror bracket is controlled to be in an open state, and the combined laser is reflected to the second iris under the action of the second reflecting mirror; when the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum are required to be obtained, namely, infrared laser and visible laser are required to be incident to a sample, the turnover mirror frame is controlled to be in a closed state, and at the moment, the second reflecting mirror does not play a role in reflection any more, so that collinear laser is directly incident to the incidence adjusting component.
After the infrared laser and the visible laser passing through the beam combining mirror can be in a collinear state by adjusting the position and the angle of the first reflecting mirror, the synchronous acquisition device can start to work formally, the turnover assembly is in a closed state at the moment, and a laser path does not irradiate the photo-thermal detector any more under the condition of closing the turnover assembly and is focused on the triangular prism through the incidence adjusting assembly. The beam combining lens is used for combining infrared laser emitted by the infrared laser source and visible laser emitted by the visible laser source to make the infrared laser and the visible laser collinear, so as to obtain collinear laser, and the collinear laser is incident to the incidence adjusting assembly and comprises the infrared laser and the visible laser.
The incidence adjusting component is used for reflecting the collinear laser, enabling the collinear laser to vertically pass through the incidence side surface of the triangular prism and be focused on the side surface of the sample, at the moment, the focal point of the collinear laser after being focused is just positioned on the side surface of the sample, and the focal point of the collinear laser is positioned right below the needle point, so that the relative positions of the visible laser and the atomic force microscope probe are adjusted through the incidence adjusting component, the spatial position coupling is completed, and the spatial position coupling of the infrared laser and the atomic force microscope probe is completed simultaneously due to the fact that the visible laser and the infrared laser are collinear, and the in-situ acquisition of the obtained atomic force microscope infrared spectrum and the total internal reflection infrared spectrum is realized by means of the spatial position coupling. It should be noted that, since the size of the atomic force microscope probe is very small, only tens of micrometers, the alignment operation of the spot and the probe of the collinear laser needs to be completed by means of the optical microscope, and meanwhile, the state of the spot can be observed by the optical microscope to determine the focusing level of the collinear laser (whether the focus is just located on the side of the sample of the triangular prism), so that the embodiment needs to be observed manually under the optical microscope to drive the incidence adjusting component according to the observation result, so that the relative positions of the visible laser and the atomic force microscope probe are adjusted under the microscope by the incidence adjusting component, the collinear laser is focused on the side of the sample vertically through the incidence side of the triangular prism, and the focus of the collinear laser is located under the needle point to complete the spatial position coupling.
Specifically, the incidence adjusting component of the embodiment includes a triaxial displacement table and an off-axis parabolic mirror mounted on the triaxial displacement table, the triaxial displacement table may be a 45 ° triaxial displacement table, the off-axis parabolic mirror is used for reflecting collinear laser, and the off-axis parabolic mirror is controlled by the 45 ° triaxial displacement table and can perform translation of a laser focus and movement along an optical axis direction. The processor is in control connection with the triaxial displacement table, and the processor is used for controlling the movement of the triaxial displacement table so that the collinear laser is vertically focused on the side surface of the sample through the incidence side surface after being reflected by the off-axis parabolic mirror, and the focal point of the collinear laser is positioned under the needle point, so that the spatial position coupling of the infrared laser and the atomic force microscope probe is completed.
When the incidence adjusting component enables the collinear laser to vertically pass through the incidence side surface of the triple prism and focus on the side surface of the sample, and the focus of the collinear laser is located right below the needle point, the sample is placed on the side surface of the sample of the triple prism, the collinear laser can generate total internal reflection at the triple prism-air interface to generate an evanescent field and reflected laser, the generated evanescent field can excite the sample, the sample can vibrate, and the generated reflected laser can emit through the emergent side surface of the triple prism and irradiate on the photo-thermal detector. The triangular prism of the present embodiment may employ a zinc selenide triangular prism, a zinc sulfide triangular prism, or a germanium triangular prism, and preferably a zinc selenide triangular prism is used.
The atomic force microscope is used for generating a micro-cantilever deflection signal of the micro-cantilever of the atomic force microscope probe after the sample is excited by an evanescent field generated after the colinear laser is focused on the side surface of the sample so as to vibrate the sample, wherein the micro-cantilever deflection signal is a change curve of deflection of the micro-cantilever along with time. Specifically, the generation process of the micro-cantilever deflection signal may include: the detection laser of the atomic force microscope irradiates on the upper surface of the micro-cantilever, and irradiates on the four-quadrant detector through reflection of the upper surface of the micro-cantilever, wherein the detection laser can be red visible light. When the sample vibrates, the micro-cantilever deflects, and at this time, the micro-cantilever reflects the detection laser to different positions of the four-quadrant detector, and the atomic force microscope generates a micro-cantilever deflection signal based on the detection laser at the different positions of the four-quadrant detector.
The photo-thermal detector is used for receiving reflected laser emitted from the emergent side face of the triangular prism to generate a reflected laser intensity signal, wherein the reflected laser is laser generated after the collinear laser is subjected to total internal reflection on the side face of the sample, and the reflected laser intensity signal is a change curve of laser intensity of the reflected laser along with time.
The processor is respectively in communication connection with the atomic force microscope and the photo-thermal detector, and is used for processing the deflection signals of the micro-cantilever and the reflected laser intensity signals to obtain an infrared spectrum of the atomic force microscope and a total internal reflection infrared spectrum. Specifically, an evanescent field generated by total internal reflection is utilized to excite a sample to vibrate, a micro-cantilever deflection signal is generated through an atomic force microscope, after demodulation and infrared laser wavelength scanning, division operation is carried out on the micro-cantilever deflection signal and a background signal of an infrared laser light source, so that an atomic force microscope infrared spectrum of the sample can be obtained, meanwhile, a reflected laser intensity signal generated by reflected laser received by a photo-thermal detector is subjected to division operation on the reflected laser intensity signal generated by the reflected laser, after the infrared laser wavelength scanning, the background signal is measured by a photo-thermal detector, and the total internal reflection infrared spectrum of the sample can be obtained, so that synchronous acquisition of the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum can be realized.
Preferably, the included angle between the sample side surface and the incident side surface is the same as the included angle between the sample side surface and the emergent side surface, so that the collinear laser vertically irradiates the sample side surface through the incident side surface, and the reflected laser vertically irradiates the photo-thermal detector through the emergent side surface, so that the quality of a reflected laser intensity signal generated by the photo-thermal detector is better, and the shape of the triangular prism is more convenient to prepare. More preferably, the prism of the present embodiment may be an equilateral triangle or an isosceles right triangle, where the sample side, the incident side, and the exit side may be arbitrarily set, where the isosceles right triangle is used, where the side corresponding to the 90 ° angle is used as the sample side, one of the other two sides is used as the incident side, and one is used as the exit side, at this time, an off-axis parabolic mirror focuses the collinear laser light vertically on the inclined plane (sample side) of the zinc selenide triangular prism through the incident side, and after the visible laser light and the infrared laser light are totally internally reflected at the inclined plane of the zinc selenide triangular prism, the visible laser light and the infrared laser light are emitted vertically through the exit side and are irradiated on the photo-thermal detector.
The sample side surface of the triangular prism is provided with gold nanoparticles, the gold nanoparticles are obtained by in-situ growth after aqueous solution of chloroauric acid is dripped on the sample side surface, and the effect of amplifying infrared signals can be achieved by arranging the gold nanoparticles.
Optionally, the synchronization acquiring device of this embodiment further includes a plurality of third mirrors that are located between the first iris and the turning component and sequentially perform optical path connection, and fig. 3 illustrates a case including 3 third mirrors, where the 3 third mirrors all function as reflection, and the 3 third mirrors are mutually matched and are used for reflecting the collinear laser to the incidence adjusting component, or reflecting the combined laser to the turning component.
The embodiment provides an atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device, which directly combines a lower incidence type atomic force microscope infrared spectrum technology and a total internal reflection infrared spectrum technology, forms a new optical path system, realizes the position coupling of infrared laser and an atomic force microscope probe, adds a photo-thermal detector at the end point of the optical path to acquire reflected laser, realizes the synchronous acquisition of the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum, and solves the problem of synchronously acquiring a polymer sample fuchsin external standard spectrum (total internal reflection infrared spectrum) and a nanometer infrared spectrum (atomic force microscope infrared spectrum).
Example 2:
the present embodiment is configured to provide an atomic force microscope-total internal reflection infrared spectrum synchronization acquisition method, which controls the synchronization acquisition device described in embodiment 1 to work, as shown in fig. 4, and includes:
s1: acquiring a micro-cantilever deflection signal generated by an atomic force microscope and a reflected laser intensity signal generated by a photo-thermal detector; the micro-cantilever deflection signal is a change curve of deflection of the micro-cantilever along with time; the reflected laser intensity signal is a change curve of the laser intensity of the reflected laser along with time;
s2: respectively processing the micro-cantilever deflection signal and the reflected laser intensity signal by using a background signal of an infrared laser light source to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum; the background signal is a curve of the laser intensity of the infrared laser along with the wave number.
The method for processing the micro-cantilever deflection signal and the reflected laser intensity signal by utilizing the background signal of the infrared laser light source to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum can comprise the following steps:
(1) And demodulating the micro-cantilever deflection signal by using a reference signal to obtain a micro-cantilever amplitude signal, wherein the reference signal is a signal which is generated by an infrared laser light source and has the same frequency as the pulse repetition frequency of the infrared laser light source, and the micro-cantilever amplitude signal is a change curve of the amplitude of the micro-cantilever along with time.
The method for determining the pulse repetition frequency of the infrared laser light source comprises the following steps: under the condition that no infrared laser irradiates a sample, a micro-cantilever deflection background signal generated by an atomic force microscope is obtained, the micro-cantilever deflection background signal at the moment is a micro-cantilever deflection signal generated by micro-cantilever deflection caused by vibration of the sample under the action of air molecules, FFT conversion is carried out on the micro-cantilever deflection background signal to obtain a frequency domain signal, the frequency corresponding to a formant (namely a peak point) in the frequency domain signal is selected as the resonance frequency of an atomic force microscope probe and the sample, the resonance frequency is set as the pulse repetition frequency of an infrared laser light source, and the infrared laser light source works with the pulse repetition frequency when the synchronous acquisition device formally works, so that the purpose of amplifying the signal can be achieved. The FFT transform is an efficient algorithm of DFT, called Fast Fourier Transform (FFT), for converting a time domain signal into a frequency domain signal.
(2) And converting the micro-cantilever amplitude signal into a micro-cantilever amplitude wave number signal, wherein the micro-cantilever amplitude wave number signal is a change curve of the amplitude of the micro-cantilever along with the wave number. Dividing the micro-cantilever amplitude wave number signal by the background signal to obtain an atomic force microscope infrared spectrum.
Because the infrared laser light source is a narrow-band light source, the emergent wave number of the infrared laser light source is linearly changed along with time, so that a wave number-time curve (namely a wave number change curve along with time) of the infrared laser light source can be obtained, and the time of the micro-cantilever amplitude signal and the wave number change curve along with time are aligned, so that the change curve of the amplitude of the micro-cantilever along with the wave number (namely the change curve of the vibration amplitude of a sample along with the wave number of infrared laser emission) can be generated, and the micro-cantilever amplitude signal is converted into the micro-cantilever amplitude wave number signal. Dividing the background signal by the obtained micro-cantilever amplitude wave number signal to perform gain adjustment on the micro-cantilever amplitude wave number signal according to the radiation intensity of the infrared laser of each wave number so as to obtain the atomic force microscope infrared spectrum of the sample.
(3) And converting the reflected laser intensity signal into a reflected laser intensity wave number signal, wherein the reflected laser intensity wave number signal is a change curve of laser intensity of the reflected laser along with wave number. Dividing the reflected laser intensity wave number signal by the background signal to obtain the total internal reflection infrared spectrum.
Because the infrared laser light source is a narrow-band light source, the emergent wave number of the infrared laser light source linearly changes along with time, so that a wave number-time curve (namely a wave number changing curve along with time) of the infrared laser light source can be obtained, and the time of the reflected laser intensity signal and the wave number changing curve along with time are aligned, so that the wave number changing curve along with the wave number of the reflected laser can be generated, and the reflected laser intensity signal is converted into the reflected laser intensity wave number signal. Dividing the background signal by the obtained reflected laser intensity wave number signal to perform gain adjustment on the reflected laser intensity wave number signal according to the radiation intensity of the infrared laser of each wave number so as to obtain the total internal reflection infrared spectrum of the sample.
The processor of this embodiment may include a phase-locked amplifier and a host, where the signal transmission path of the synchronization acquiring device is shown in fig. 5, and the data processing flow is shown in fig. 6. The atomic force microscope transmits a micro-cantilever deflection background signal to the lock-in amplifier, the lock-in amplifier calculates the resonance frequency of an atomic force microscope probe and a sample through FFT conversion and transmits the resonance frequency to the infrared laser light source, the infrared laser light source sets the resonance frequency to be the pulse repetition frequency of infrared laser, so that the infrared laser is generated in the formal working process of the synchronous acquisition device, and meanwhile, a reference signal with the same frequency as the pulse repetition frequency is generated, and the reference signal is transmitted to the lock-in amplifier. The phase-locked amplifier demodulates the micro-cantilever deflection signal acquired by the atomic force microscope according to the received reference signal to obtain the amplitude of the micro-cantilever under the pulse repetition frequency, generates a micro-cantilever amplitude signal, transmits the calculated micro-cantilever amplitude signal to the host, the host draws an amplitude-wave number curve (namely the micro-cantilever amplitude wave number signal) through the emergent wave number (wave number refers to the reciprocal of the wavelength) of the infrared laser light source, and divides the micro-cantilever amplitude wave number signal by the background signal to perform gain adjustment on the micro-cantilever amplitude wave number signal according to the radiation intensity of each wave number, so that the infrared spectrum of the atomic force microscope of the sample can be obtained. Meanwhile, the photo-thermal detector (namely, the photo-thermal detector) transmits the laser intensity (namely, the reflected laser intensity signal) of the reflected laser received in real time to the lock-in amplifier, the lock-in amplifier outputs the reflected laser intensity signal to the host, the host draws a laser intensity-wave number curve (namely, the reflected laser intensity wave number signal) through the emergent wave number of the infrared laser light source, and then divides the reflected laser intensity wave number signal by the background signal so as to carry out gain adjustment on the reflected laser intensity wave number signal according to the radiation intensity of each wave number, and the total internal reflection infrared spectrum of the sample is obtained. Finally, comparing the two data (the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum) to obtain a detection result.
The background signal acquisition mode is as follows: and collecting infrared laser emitted by the infrared laser light source by the photo-thermal detector, and recording the infrared laser in software to obtain a background signal.
In order to verify the operating state of the synchronous detection device, several groups of standard samples are used to verify the function of the synchronous detection device:
(1) Spin-coated polystyrene ultra-thin film
Since the infrared absorption intensity of the polymer ultra-thin film is extremely weak, a suitable signal amplification means is required. The effect of amplifying the infrared signal can be achieved by growing gold nanoparticles on the side of the sample of the zinc selenide triangular prism for total internal reflection, and the gold nanoparticles can be grown in situ by using the aqueous solution of chloroauric acid to be added dropwise on the side of the sample of the zinc selenide triangular prism. Through experiments, the condition that the concentration of the solution is 5mM (also can be written as 5 mmol/L), the mol/L is a concentration unit and is abbreviated as M, and the modification time (namely, the time for soaking the side surface of a sample of the zinc selenide triangular prism by using the aqueous solution of chloroauric acid) is 40s can enable the infrared signal to reach the optimal signal-to-noise ratio level.
And selecting a spin-coated polystyrene ultra-thin film with the thickness of 35nm as a sample, and collecting spectral data. The micro-cantilever amplitude-wave number curve (micro-cantilever amplitude wave number signal) and the background signal are shown in the same spectrum, as shown in fig. 7, the solid line in fig. 7 is the micro-cantilever amplitude wave number signal, and the broken line is the background signal. The micro-cantilever amplitude wave number signal and the background signal are subjected to division operation to perform gain adjustment on the spectrum, so that an atomic force microscope infrared spectrum of the spin-coated polystyrene ultrathin film is obtained, and the atomic force microscope infrared spectrum is shown in fig. 8. 1452cm can be observed by FIG. 8 -1 ，1492cm -1 And 1601cm -1 Absorption peaks, which correspond to the characteristic absorption peaks of polystyrene.
The reflected laser intensity wavenumber signal and the background signal are shown in the same laser intensity-wavenumber spectrum, as shown in fig. 9, with the solid line in fig. 9 being the reflected laser intensity wavenumber signal and the dashed line being the background signal. The reflected laser intensity wavenumber signal and the background signal are divided to gain adjust the spectrum, resulting in a total internal reflection infrared spectrum of the spin-coated polystyrene ultrathin film, as shown in fig. 10. 1452cm can be observed by FIG. 10 -1 ，1492cm -1 And 1602cm -1 Absorption peaks, which correspond to the characteristic absorption peaks of polystyrene.
The atomic force microscope infrared spectrum and the total internal reflection infrared spectrum are displayed in a superimposed mode, and as shown in fig. 11, the same absorption peak can be observed, and the technology is proved to have the infrared detection capability for the polymer ultrathin film.
(2) Spin-on polyvinyl alcohol cinnamate film
A polyvinyl alcohol cinnamate film with a thickness of 100nm is selected as a sample for spectrum acquisition. Will be microThe cantilever amplitude-wave number curve (micro-cantilever amplitude wave number signal) and the background signal are shown in the same spectrum, as shown in fig. 12, where the solid line in fig. 12 is the micro-cantilever amplitude wave number signal and the broken line is the background signal. The micro-cantilever amplitude wave number signal and the background signal are subjected to division operation to perform gain adjustment on the spectrum, so that an atomic force microscope infrared spectrum of the spin-coated polyvinyl alcohol cinnamate film is obtained, and the atomic force microscope infrared spectrum is shown in fig. 13. 979cm can be observed by FIG. 13 -1 ，1171cm -1 ，1202cm -1 ，1281cm -1 ，1309cm -1 ，1449cm -1 ，1496cm -1 ，1577cm -1 ，1636cm -1 And 1709cm -1 The absorption peaks correspond to the characteristic absorption peaks of polyvinyl alcohol cinnamate.
The reflected laser intensity wavenumber signal and the background signal are shown in the same laser intensity-wavenumber spectrum, as shown in fig. 14, where the solid line in fig. 14 is the reflected laser intensity wavenumber signal and the dashed line is the background signal. The reflected laser intensity wavenumber signal and the background signal are divided to gain adjust the spectrum, resulting in a total internal reflection infrared spectrum of the spin-coated polyvinyl alcohol cinnamate film, as shown in fig. 15. 979cm can be observed by FIG. 15 -1 ，1171cm -1 ，1202cm -1 ，1281cm -1 ，1309cm -1 ，1449cm -1 ，1496cm -1 ，1577cm -1 ，1636cm -1 And 1709cm -1 The absorption peaks correspond to the characteristic absorption peaks of polyvinyl alcohol cinnamate.
254nm ultraviolet irradiation is carried out on the spin-coating polyvinyl cinnamate vinyl alcohol ester film to induce chemical crosslinking reaction to occur in the spin-coating polyvinyl cinnamate vinyl alcohol ester film, the atomic force microscope infrared spectrum test is carried out again, the obtained spectrum data are shown in fig. 16, and the corresponding C=C double bond 1636cm can be observed -1 Disappearance of the absorption peak at and corresponding carbonyl 1709cm -1 The blue shift behavior of the absorption peak at the position proves the accurate spectrum detection capability of the synchronous acquisition device.
(3) Pouring polystyrene-polymethyl methacrylate blend film
For an atomic force microscope infrared spectrum system, nano-scale infrared imaging can be realized, which is a test The polystyrene-polymethyl methacrylate blend film is prepared by pouring by taking ethyl acetate as a solvent. At 1728cm on the surface of the film -1 (characteristic absorption peak of polymethyl methacrylate) and 1492cm -1 (polystyrene characteristic absorption peak) infrared imaging was performed, and the results are shown in fig. 17. When imaging is carried out by two wave numbers respectively, two phases existing in the sample can be observed to have stronger absorption to infrared light with single wavelength respectively, the nanometer phase-separating behavior of the sample can be clearly distinguished from the imaging result, and the nanometer infrared imaging function of the instrument can be verified.
For atomic force microscope infrared spectroscopy, since an atomic force microscope probe is used as a detector, confirmation of the state of a sample is often required in an actual sample test using conventional infrared spectroscopy. For more sensitive samples (such as those with photoinitiation capabilities), this ex-situ detection approach is difficult to ensure experimental accuracy. There is therefore a need for a combination technique that can collect the total internal reflection infrared spectrum of a sample while simultaneously acquiring the atomic force microscope infrared spectrum. Therefore, the embodiment can realize in-situ and simultaneous acquisition of two infrared spectrums of a single sample by combining an autonomous writing data processing mode through the design of the synchronous acquisition device of the atomic force microscope-total internal reflection infrared spectrums and the light path design. In addition, the zinc selenide prism is treated by chloroauric acid solution to enhance the signal intensity and the signal-to-noise ratio of an atomic force microscope infrared spectrum, namely, the infrared absorption signal intensity of the sample is successfully enhanced by using gold nanoparticles, so that the technology can be applied to infrared detection of a polymer ultrathin film, and has proper detection capability on the polymer film sample commonly used in the fields of photoelectric devices and the like.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (10)
1. An atomic force microscope-total internal reflection infrared spectrum synchronous acquisition device is characterized by comprising an infrared laser source, a visible laser source, a beam combining lens, an incidence adjusting component, a triple prism, an atomic force microscope, a photo-thermal detector and a processor; a sample is placed on the sample side surface of the triangular prism; the tip of an atomic force microscope probe of the atomic force microscope is contacted with the sample;
the beam combining lens is used for combining infrared laser emitted by the infrared laser source and visible laser emitted by the visible laser source to make the infrared laser and the visible laser collinear to obtain collinear laser, and the collinear laser is incident to the incidence adjusting component; the collinear laser comprises the infrared laser and the visible laser;
The incidence adjusting component is used for reflecting the collinear laser, enabling the collinear laser to vertically pass through the incidence side surface of the triangular prism and focus on the side surface of the sample, and enabling the focus of the collinear laser to be located right below the needle point;
the atomic force microscope is used for generating a micro-cantilever deflection signal of the micro-cantilever of the atomic force microscope probe after the collinear laser is focused on the side surface of the sample; the micro-cantilever deflection signal is a change curve of deflection of the micro-cantilever along with time;
the photo-thermal detector is used for receiving reflected laser emitted from the emergent side surface of the triangular prism and generating a reflected laser intensity signal; the reflected laser is generated after the collinear laser generates total internal reflection on the side surface of the sample; the reflected laser intensity signal is a change curve of the laser intensity of the reflected laser along with time;
the processor is respectively in communication connection with the atomic force microscope and the photo-thermal detector; the processor is used for processing the micro-cantilever deflection signal and the reflected laser intensity signal to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum.
2. The synchronization acquiring device according to claim 1, characterized in that the synchronization acquiring device further comprises: the device comprises a first reflecting mirror, a first iris diaphragm, a turnover assembly and a second iris diaphragm;
the first reflecting mirror is positioned between the infrared laser light source and the beam combining mirror; the first reflecting mirror is used for reflecting the infrared laser to the beam combining mirror;
the beam combining lens is used for combining the infrared laser and the visible laser to obtain combined laser, and the combined laser is incident to the first iris diaphragm;
the apertures of the first iris diaphragm and the second iris diaphragm are in a minimum state; the first iris diaphragm is used for transmitting the combined laser to the turnover assembly;
the overturning assembly is used for reflecting the combined laser to the second iris diaphragm;
the second iris diaphragm is used for transmitting the combined laser to the photo-thermal detector;
the photo-thermal detector is used for receiving the combined laser and determining a first power of infrared laser and a second power of visible laser in the combined laser;
the processor is configured to adjust the position and angle of the first mirror based on the first power and the second power until the first power and the second power both reach a maximum value.
3. The synchronization acquiring device according to claim 2, wherein the flipping assembly comprises a flipping frame and a second mirror mounted on the flipping frame; the processor is in control connection with the overturning frame; when the position and the angle of the first reflecting mirror need to be adjusted, controlling the turnover mirror frame to be in an open state, so that the combined laser is reflected to the second iris diaphragm; when the atomic force microscope infrared spectrum and the total internal reflection infrared spectrum are required to be obtained, the turnover frame is controlled to be in a closed state, so that the collinear laser is incident to the incidence adjusting component.
4. The synchronization acquiring device according to claim 1, wherein the incidence adjustment assembly comprises a three-axis displacement stage and an off-axis parabolic mirror mounted on the three-axis displacement stage; the off-axis parabolic mirror is used for reflecting the collinear laser;
the processor is in control connection with the triaxial displacement table; the processor is used for controlling the movement of the triaxial displacement table so that the collinear laser is focused on the side surface of the sample vertically through the incidence side surface after being reflected by the off-axis parabolic mirror, and the focus of the collinear laser is positioned right below the needle point.
5. The simultaneous acquisition device of claim 1, wherein the sample has gold nanoparticles on its sides; the gold nanoparticles are obtained by in-situ growth after the aqueous solution of chloroauric acid is dripped on the side surface of the sample.
6. The synchronization acquiring device according to claim 1, wherein an angle between the sample side and the entrance side is the same as an angle between the sample side and the exit side.
7. The synchronization acquiring device according to claim 2, further comprising a plurality of third mirrors positioned between the first iris and the flipping assembly in sequence for optical path connection.
8. An atomic force microscope-total internal reflection infrared spectrum synchronous acquisition method for controlling the synchronous acquisition device according to claim 1 to work, characterized in that the synchronous acquisition method comprises the following steps:
acquiring a micro-cantilever deflection signal generated by an atomic force microscope and a reflected laser intensity signal generated by a photo-thermal detector; the micro-cantilever deflection signal is a change curve of deflection of the micro-cantilever along with time; the reflected laser intensity signal is a change curve of the laser intensity of the reflected laser along with time;
Respectively processing the micro-cantilever deflection signal and the reflected laser intensity signal by using a background signal of an infrared laser light source to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum; the background signal is a curve of the laser intensity of the infrared laser along with the wave number.
9. The method according to claim 8, wherein the processing the micro-cantilever deflection signal and the reflected laser intensity signal by using the background signal of the infrared laser light source to obtain an atomic force microscope infrared spectrum and a total internal reflection infrared spectrum specifically includes:
demodulating the micro-cantilever deflection signal by using a reference signal to obtain a micro-cantilever amplitude signal; the reference signal is a signal which is generated by the infrared laser light source and has the same frequency as the pulse repetition frequency of the infrared laser light source; the micro-cantilever amplitude signal is a change curve of the amplitude of the micro-cantilever along with time;
converting the micro-cantilever amplitude signal into a micro-cantilever amplitude wave number signal; the micro-cantilever amplitude wave number signal is a change curve of the amplitude of the micro-cantilever along with the wave number;
dividing the micro-cantilever amplitude wave number signal by the background signal to obtain an atomic force microscope infrared spectrum;
Converting the reflected laser intensity signal into a reflected laser intensity wavenumber signal; the reflected laser intensity wave number signal is a change curve of laser intensity of the reflected laser along with wave number;
dividing the reflected laser intensity wave number signal by the background signal to obtain a total internal reflection infrared spectrum.
10. The synchronization acquisition method according to claim 9, wherein the method for determining the pulse repetition rate of the infrared laser light source includes:
under the condition of no infrared laser irradiation on a sample, acquiring a micro-cantilever deflection background signal generated by an atomic force microscope; performing FFT conversion on the micro-cantilever deflection background signal to obtain the resonance frequency of the atomic force microscope probe and the sample; the resonance frequency is set to a pulse repetition frequency of the infrared laser light source.
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