WO2021050041A1 - Spectromètre d'absorption transitoire à correction de photo-événement - Google Patents

Spectromètre d'absorption transitoire à correction de photo-événement Download PDF

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Publication number
WO2021050041A1
WO2021050041A1 PCT/US2019/050228 US2019050228W WO2021050041A1 WO 2021050041 A1 WO2021050041 A1 WO 2021050041A1 US 2019050228 W US2019050228 W US 2019050228W WO 2021050041 A1 WO2021050041 A1 WO 2021050041A1
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Prior art keywords
monitoring light
transient absorption
light beam
sample
photo
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PCT/US2019/050228
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English (en)
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Christopher Grieco
Eric R. KENNEHAN
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Magnitude Instruments Llc
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Priority to PCT/US2019/050228 priority Critical patent/WO2021050041A1/fr
Publication of WO2021050041A1 publication Critical patent/WO2021050041A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
    • G01J3/0232—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using shutters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2889—Rapid scan spectrometers; Time resolved spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/1717—Systems in which incident light is modified in accordance with the properties of the material investigated with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/1717—Systems in which incident light is modified in accordance with the properties of the material investigated with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
    • G01N2021/1721—Electromodulation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/1717—Systems in which incident light is modified in accordance with the properties of the material investigated with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
    • G01N2021/1725—Modulation of properties by light, e.g. photoreflectance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N2021/3125—Measuring the absorption by excited molecules

Definitions

  • Nanosecond-to-millisecond time-resolved transient absorption spectroscopy is a spec troscopic technique that measures dynamics of a number of chemical, biochemical, and material systems. These dynamics observed by transient absorption spectroscopy provide insight into the molecular properties that produce chemical and physical properties of the analyzed systems. For example, charge trapping and recombination occurring in solar cells, protein folding, and a number of other reactions occur on the nanosecond to millisecond timescale and can be observed through this technique.
  • transient absorption spectroscopy One of the main limitations of nanosecond-to-millisecond time-resolved transient absorption spectroscopy is the small signal sizes.
  • the signals that are measured by this technique are produced by small subpopulations of the entire sample, such as a fraction of trapped charges of all charges generated.
  • Transient absorption spectroscopy also is l imi ted because it requires low excitation laser fiuence to prevent sample degradation and to allow physical or chemical processes to be observed under a linear signal response regime.
  • a superior method for acquiring nanosecond-to-millisecond, transient absorption signals is flash photolysis spectroscopy. This method is advantageous because the detected signal is electronically time-resolved directly by a photodetector, allowing the complete sampling of time points across the nanosecond-to-millisecond timescale to be collected for a single laser pulse. Flash photolysis uses a short light pulse (e.g. ultraviolet, visible, near-infrared, or mid-infrared wavelength pulse of light) to induce physical or chemical changes in a sample. These changes are monitored using a different beam of light (monitoring light beam).
  • a short light pulse e.g. ultraviolet, visible, near-infrared, or mid-infrared wavelength pulse of light
  • the monitoring light beam is typically, but not limited to, a broadband or narrowband, continuous-wave (cw) light source that either spans or can be tuned throughout the ultraviolet, visible, near-infrared, and mid-infrared wavelengths and is detected by a photodetector.
  • the photodetector voltage photovoltage
  • This modulated voltage signal is used to calculate the “transient absorption signal.”
  • the transient absorption signal from the sample is very small, which translates to very small changes in voltage that must be measured accurately — typically on the order of microvolts.
  • the short light pulse that is required to make a transient absorption measurement often creates additional unwanted signals that are observed by the photodetector.
  • These signals which are generally referred herein as “photo-event signals” and include, for instance, photo luminescence, phosphorescence, photo-emission, luminescence, or scattered light, obscure the desired transient absorption signal.
  • the photo event signal is typically orders of magnitude larger than the transient absorption signal, creating a great challenge for the flash photolysis method of transient absorption spectroscopy because this photo-event signal must carefully be accounted for to obtain an accurate transient absorption measurement.
  • Embodiments of the present disclosure relate to, among other things, a transient absorption spectrometer that provides for real-time photo-event correction.
  • the transient absorption spectrometer includes an excitation source for producing excitation pulses for exciting a sample, a monitoring light source for producing a monitoring light beam for measuring the transient absorption spectrum of the sample, and a detector for detecting light, including signals of the monitoring light beam.
  • the transient absorption spectrometer also includes an automated light shutter for blocking the monitoring light beam from interacting with the sample. In operation, the shutter is controlled to: (1) unblock the monitoring light beam to perform a transient absorption measurement that includes a photo event signal; and (2) block the monitoring beam to measure the photo-event signal.
  • a corrected transient absorption spectrum is determined by subtracting the photo-event signal measurement from the transient absorption measurement that includes a photo-event signal.
  • the transient absorption and photo-event measurements are performed close in time, avoiding errors in subtraction associated with drifts in the optical power of the short excitation pulse.
  • FIG. 1 is a block diagram illustrating a schematic of a time-resolved transient absorption spectrometer according to an embodiment of the present disclosure
  • FIG. 2 is a flow diagram showing a method for generating a transient absorption spectrum using a shutter to provide for photo-event correction in accordance with an embodiment of the present disclosure
  • FIG. 3 is a graph of transient absorption spectra of a PbS quantum dot film generated using real-time photo-event subtraction in accordance with an embodiment of the present disclosure
  • FIG. 4 is a graph of transient absorption spectra of a PbS quantum dot film generated using post-measurement photo-event subtraction
  • FIG. 5 is a graph of photoluminescence spectra of a PbS quantum dot film.
  • FIG. 6 is a block diagram of an exemplary computing device suitable for use in some implementations of the presen t disclosure.
  • Embodiments of the present disclosure are directed to a transient absorption spectrometer that provides a significant improvement over previous approaches of eliminating the excitation pulse induced photo-event from the transient absorption spectra.
  • Previous approaches for photo-event subtraction include measuring transient absorption spectra in its entirety before blocking a monitoring light beam and collecting one measurement of the photo-event. These previous approaches are inaccurate, for instance, due to possible power variation in the excitation source during the measurement of the spectra.
  • Embodiments of the present disclosure address this problem of previous approaches by providing a transient absorption spectrometer that iteratively subtracts the photo-event signal from the transient absorbance signal in real-time.
  • This real-time subtraction is a measurement of the photo-event directly following the measurement of the transient absorption signal at each wavelength or at each of a number of excitation events for a single wavelength.
  • the photo-event is measured iteratively, the error introduced from power variation in the excitation source is minimized and the resultant measured transient absorption more closely resembles the true transient absorption of the sample.
  • the transient absorption spectrometer 100 includes an excitation source 102, mirror 104, monitoring light source 106, light shutter 108, sample position 110, sample compartment 112, detector 114, and computing device 116.
  • the components of the transient absorption spectrometer 100 shown in FIG. 1 are provided by way of example only and not limitation Other arrangements and components can be used in addition to or instead of those shown, and some components may be omitted altogether.
  • the excitation source 102 produces an excitation pulse for exciting a sample placed at the sample position 110 in the sample compartment 112.
  • the excitation source 102 is a light source that produces a light pulse to induce changes in the sample.
  • the light pulse may be, for example, an ultraviolet, visible, near-infrared, or mid- infrared wavelength pulse of light.
  • the excitation source 102 may be anNd:YAG laser.
  • a mirror 104 directs the excitation pulse from the excitation source 102 onto the sample position 110 in the sample compartment 112. It should be understood that any number of mirrors (or no mirror) may be employed within the scope of embodiments described herein.
  • the excitation source 102 produces an excitation pulse that is a(n) optical, chemical, physical, thermal, or electrical stimuli.
  • the excitation pulse could be a pulse from a laser, a change in the chemical environment by introducing a foreign molecule, introducing a physical stress, inducing a thermal signal by heating the sample using light, or inducing an electric current by an AC generator.
  • the monitoring light source 106 is a light source that produces a monitoring light beam for monitoring changes experienced by a sample placed at the sample position 110 in the sample compartment 112.
  • the monitoring light beam produced by the monitoring light source 106 is a broadband or narrowband continuous wave light beam that may be ultraviolet, visible, near-infrared, mid-infrared, terahertz, and/or X-ray wavelengths.
  • the monitoring light source may be a continuous wave laser, a broadband incandescent light source, any other broadband light source, or any narrowband light source.
  • the light shutter 108 comprises a device, with or without mechanical components, that is operable to block and unblock the monitoring light beam.
  • blocking the monitoring light beam refers to preventing the monitoring light beam from interacting with a sample and/or being detected by the detector 114. Among other things, this may include redirecting the monitoring light beam off the path to the sample location and/or detector 114.
  • unblocking the monitoring light beam refers to allowing the monitoring light beam to interact with a sample and/or be detected by the detector 114.
  • the light shutter 108 comprises a beam block that is mechanically moved to block or unblock the monitoring light beam produced by the monitoring light sources.
  • the beam block can be, but is not limited to, a sliding gate, a rotating gate, a shutter wheel, or any other opaque item.
  • the light shutter 108 may also include a stepper motor, a servo motor, a DC electric motor, or any other mechanical operator to move the beam block to block and unblock the monitoring light beam.
  • the light shutter 108 comprises a chopping wheel system that includes a fan blade with solid opaque portions and open voids. The chopping wheel rotates at a desired frequency to block and unblock the monitoring light beam at a rate allowing for measurement of an apparent change of transmission and photo-event for a desired number of excitation pulses (as will be described in further detail below).
  • the light shutter 108 comprises a non-mechanical device.
  • the light shutter 108 may be an electrical optical modulator, a Kerr gate, a light induced modulator, or any other device that may change polarization to block the monitoring light beam.
  • the sample compartment 112 may include an enclosure to contain any stray light to prevent any potential injury to the user.
  • the sample is housed in the sample compartment 112 such that the excitation pulse and the monitoring light beam overlap on the sample or object to be analyzed.
  • the sample may be a liquid or a film. Liquid samples may be held static, or may be flowed during experiments in temperature-controllable liquid flow cells pumped by peristaltic pumps. Samples may be optionally, but not limited, to being measured inside of temperature-controllable cryogenic chambers under vacuum, or in some cases under chemical vapor atmosphere, including air, nitrogen, argon, and oxygen.
  • An example of a sample that is a film is a thin film of a semiconducting material deposited onto a substrate.
  • the excitation pulse may excite electrons, which may be monitored by the monitoring light beam to determine how they relax to the ground state.
  • the detector 114 converts light into an electrical signal, such as photovoltage signals.
  • the detector 114 may be, but is not limited to, a(n) MCT detector, phototube, photomultiplier tube, photodiode, or charge coupled device (CCD).
  • the detector 114 may be capable of measuring light for synchronous measurement of both the monitoring light beam in the absence of an excitation pulse and the change in the monitoring light beam signal between a signal with the excitation pulse present and a signal in absence of the excitation pulse.
  • the detector 114 may be any device suitable for the ultraviolet, visible, near-infrared, mid-infrared, terahertz, or X-ray spectral ranges.
  • the computer 116 comprises a computing device, such as the computing device 600 of FIG. 6, discussed below.
  • the computer 116 controls operation of the excitation source 102 to control excitation of the sample using excitation pulses. Additionally, the computer 116 controls operation of the light shutter 108 to thereby control whether the monitoring light beam is transmitted from the monitoring light source 106 interacts with the sample and is then directed to the detector 114.
  • the computer 116 also receives signal measurements (e.g., photovoltage signal measurements) from the detector 114. Using the signal measurements, the computer 116 generates and outputs transient absorption spectra, as described in further detail below.
  • the computer 116 controls operation of the monitoring light source 106 by turning the monitoring light source 106 on and off depending on whether the monitoring light source 106 is needed for a measurement.
  • the computer 116 may turn on the monitoring light source 106 to measure the change in transmission of the sample.
  • the computer 116 may turn off the monitoring light source 106 in order to measure a photo-event signal without the monitoring light beam present.
  • the monitoring light source 106 is instead turned on or off to control whether the monitoring light beam interacts with the sample and detected by the detector 114.
  • a flow diagram is provided showing operation of the transient absorption spectrometer 100 to generate a transient absorption signal.
  • the light shutter 108 is controlled to unblock the monitoring light beam from the monitoring light source 106 to allow' the monitoring light beam to impinge on the sample at the sample position 110 to the detector 114.
  • the excitation source 102 is operated to produce one or more excitation pulses to excite the sample.
  • a monitoring light beam signal measurement is recorded from the monitoring light beam interacting with the sample with an excitation pulse present, as shown at block 206.
  • a monitoring light beam signal measurement is recorded from the monitoring light beam interacting with the sample in the absence of an excitation pulse, as shown at block 208.
  • a “monitoring light beam signal measurement” comprises a measurement of a transmission signal, reflection signal, diffuse-reflectance signal, and/or other signal resulting from the monitoring light beam interacting with a sample.
  • an apparent change in transmission is determined by calculating the difference between the monitoring light beam signal measurement following an excitation pulse and the monitoring light beam signal measurement without the excitation pulse present. Because the DT apparent is calculated from monitoring light beam signal measurements, the DT apparent accounts for transmission, reflection, diffuse-reflectance and/or other signals. In some configurations, the process of recording a monitoring light beam signal measurement in the presence of an excitation pulse and a monitoring light beam signal measurement in the absence of an excitation pulse may be performed once or repeated a number of times (the number of times may be configurable by the instrument user). If multiple monitoring light beam signal measurements are recorded, the DT apparent may be calculated as an average over the multiple monitoring light beam signal measurements.
  • the ATapparent includes an additional signal that the detector 114 measures and is superimposed with the monitoring light beam signal measurements.
  • This extra signal referred to herein as a photo-event signal (PE)
  • PE photo-event signal
  • a PE signal measurement is made and subtracted from the DT apparent .
  • the light shutter 108 is operated to block the monitoring light beam from the monitoring light source 106, thereby preventing the monitoring light beam. from interacting with the sample, as shown at block 212.
  • the excitation source 102 is operated to produce an excitation pulse that interacts with the sample causing the photo-physical event, as shown at block 214, and a PE signal measurement is recorded, as shown at block 216.
  • the PE signal measurement is from a single PE signal, while in other configurations, the PE signal measurement is an average over multiple PE signals. Additionally, it should be understood by one skilled in the art that the PE signal measurement may be made before or after measurement of the DT apparent .
  • the PE signal measurement is subtracted from the DT apparent to determine DT in real time, as shown at block 218.
  • the DT accounts for transmission, reflection, diffuse-reflectance and/or other signals.
  • the process of obtaining a PE signal measurement directly following or directly prior to the measurement of DT apparent and subtraction of the PE signal measurement is performed at a particular wavelength and can be repeated as an iterative process for each of a number of different wavelengths. In other words, the above-described process of determining the DT is iteratively performed for each of a number of different wavelengths.
  • real-time subtraction of the photo-event can be performed by measuring a portion of the desired excitation events to be averaged together at one wavelength.
  • subtraction of the photo-event could be performed iteratively every excitation event.
  • the process of measuring DT apparent , obtaining a PE signal measurement, and subtracting the PE signal measurement from AT apparert can be iteratively repeated for each excitation event for a number of excitation events.
  • An excitation event refers to the process of exciting the sample with an excitation pulse to meas ure DT apparent .
  • Data representative of the DA, DT, and/or PE signal is output for presentation to a user, as shown at block 222.
  • FIG. 3 show's a graph of transient absorption spectra of a sample of a PbS quantum dot film generated using real-time photo-event subtraction in accordance with an embodiment of the present disclosure.
  • the transient absorption spectra of FIG 3 were generated using a transient absorption spectrometer that iteratively measured the excitation pulse induced photo-event at each wavelength to account for any variation in excitation power during the measurement of the entire spectra
  • FIG. 4 shows a graph of transient absorption spectra of the same sample of a PbS quantum dot film as in FIG. 3 but using a conventional approach of subtracting the photo-event signal by measuring the photo-event signal following measurement of the entire dataset
  • the transient absorption spectra of FIG 3 exhibit a significant improvement in the accuracy of the spectra by subtracting the photo-event in real time as opposed to the transient absorption spectra of FIG. 4 using a conventional approach in which the photo-event signal is measured following measurement of the entire spectra. For instance, the peak at around 900 rnn in FIG. 4 is shifted and in an incorrect position. Additionally, in FIG. 4, an artificial signal appears around 1020 nni, which is an artifact from incorrect subtraction of the photo-event.
  • FIG. 5 shows a graph of photo-event spectra generated when producing the transient absorption spectra of FIG. 3. Although not directly seen from a comparison of the figures, the photo-event signal is significantly larger than the signal from the modulation of the monitoring light beam.
  • computing device 600 includes a bus 610 that directly or indirectly couples the following devices: memory 612, one or more processors 614, one or more presentation components 616, input/output (I/O) ports 618, input/output components 620, and illustrative power supply 622.
  • Bus 610 represents what may be one or more busses (such as an address bus, data bus, or combination thereof).
  • I/O input/output
  • FIG. 6 represents what may be one or more busses (such as an address bus, data bus, or combination thereof).
  • FIG. 6 is merely illustrative of an exemplary computing device that can be used in connection with one or more embodiments of the present disclosure. Distinction is not made between such categories as “workstation,” “server,” “laptop,” “hand-held device,” etc., as ail are contemplated within the scope of FIG. 6 and reference to “computing device.”
  • Computer-readable media can be any available media that can be accessed by computing device 600 and includes both volatile and nonvolatile media, removable and non removable media.
  • Computer-readable media may comprise computer storage media and communication media.
  • Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data.
  • Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computing device 600.
  • Computer storage media does not comprise signals per se.
  • Communication media typically embodies computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media.
  • modulated data signal means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal.
  • communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of any of the above should also be included within the scope of computer-readable media.
  • Memory 612 includes computer storage media in the form of volatile and/or nonvolatile memory.
  • the memory may be removable, non-removable, or a combination thereof.
  • Exemplary hardware devices include solid-state memory, hard drives, optical-disc drives, etc.
  • Computing device 600 includes one or more processors that read data from various entities such as memory 612 or I/O components 620.
  • Presentation component(s) 616 present data indications to a user or other device.
  • Exemplary presentation components include a display device, speaker, printing component, vibrating component, etc.
  • I/O ports 618 allow computing device 600 to be logically coupled to other devices including I/O components 620, some of which may be built in. Illustrative components include a microphone, joystick, game pad, satellite dish, scanner, printer, wireless device, etc.
  • the I/O components 620 may provide a natural user interface (NUI) that processes air gestures, voice, or other physiological inputs generated by a user. In some instance, inputs may be transmitted to an appropriate network element for further processing.
  • NUI may implement any combination of speech recognition, touch and stylus recognition, facial recognition, biometric recognition gesture recognition both on screen and adjacent to the screen, air gestures, head and eye-tracking, and touch recognition associated with displays on the computing device 600.
  • the computing device 600 may be equipped with depth cameras, such as stereoscopic camera systems, infrared camera systems, RGB camera systems, and combinations of these for gesture detection and recognition. Additionally, the computing device 600 may be equipped with accelerometers or gyroscopes that enable detection of motion.
  • depth cameras such as stereoscopic camera systems, infrared camera systems, RGB camera systems, and combinations of these for gesture detection and recognition.
  • the computing device 600 may be equipped with accelerometers or gyroscopes that enable detection of motion.
  • step and/or “block” may be used herein to connote different elements of methods employed, the terms should not be interpreted as implying any particular order among or between various steps herein disciosed unless and except when the order of individual steps is explicitly described.
  • a transient absorption spectrometer instrument comprising: an excitation source for generating an excitation pulse inducing a change in a sample; a monitoring light source for generating a monitoring light beam used to monitor the change in the sample induced by the excitation pulse; a detector to measure the monitoring light beam that has interacted with the sample; and a light shutter to automatically control whether the monitoring light beam interacts with the sample and is detected by the detector.
  • the transient absorption spectrometer of clause 1 wherein the monitoring light source produces an ultra-violet, visible, near infrared, mid-infrared, terahertz, and/or X-ray beam of light.
  • Clause 5. The transient absorption spectrometer of clause 1, wherein the detector is configured to measure light in ultra-violet, visible, near infrared, mid-infrared, terahertz, and/or X-ray spectral regions.
  • the transient absorption spectrometer of clause 6, wdierein the light shutter comprises a stepper motor for automatically moving the beam block to block the monitoring light beam.
  • Clause 8 The transient absorption spectrometer of clause 6, wherein the light shutter comprises a servo motor for automatically moving the beam block to block the monitoring light beam.
  • Clause 11 The transient absorption spectrometer of clause 1 , wherein the light shutter comprises a non-mechanical device operable to block and unblock the monitoring light beam.
  • transient absorption spectrometer of clause 1 further comprising: a processor configured to automatically control the light shutter to block or unblock the monitoring light beam.
  • a transient absorption spectrometer system comprising: a processor configured to: iteratively repeat for each wavelength from a plurality of wavelengths: control a light shutter to unblock a monitoring light beam from a monitoring light source and allow' the monitoring light beam to interact with a sample and be directed to a detector; receive, from the detector, a first signal measurement from the monitoring light beam without a presence of an excitation pulse; receive, from the detector, a second signal measurement from the monitoring light beam following excitation of the sample by an excitation pulse; control the light shutter to block the monitoring light beam preventing the monitoring light beam from interacting with the sample and being directed to the detector; and receive, from the detector, a photo-event signal measurement based on a photo-event from the sample following an excitation pulse with the monitoring light beam blocked by the light shutter, the photo-event signal measurement being made by the detector directly before or directly after the detector making the first signal measurement and the second signal measurement; and the processor further configured to generate a transient absorption measurement of the sample using at least
  • Clause 14 The transient absorption spectrometer system of clause 13, wherein the first signal measurement is based on a plurality of signals received at the detector without a presence of an exci tation pulse.
  • Clause 15 The transient absorption spectrometer system of clause 13, wherein the second signal measurement is based on a plurality of signals received at the detector following excitation of the sample by an excitation pulse.
  • Clause 16 The transient absorption spectrometer system of clause 13, wherein the processor is further configured to iteratively repeat for each wavelength from the plurality of wavelengths: calculate an apparent change in transmission from a difference between the first signal measurement and the second signal measurement; calculate an actual change in transmission by subtracting the photo-event signal measurement from the apparent change in transmission; and wherein the transient absorption of the sample is generated using the actual change in transmission and a steady-state signal measurement of the monitoring light beam without presence of an excitation pulse.
  • transient absorption spectrometer system of clause 16 wherein the processor is further configured to: provide, for display, at least one selected from the following: the transient absorption, the apparent change in transmission, and the photo-event signal measurement for each wavelength from the plurality' of wavelengths.
  • a method of real time subtraction of a photo-event using a transient absorption spectrometer comprising: iteratively repeating for each of a number of excitation events for a wavelength: automatically controlling a light shutter to unblock a monitoring light beam from a monitoring light source and allow the monitoring light beam to interact with a sample and proceed to a detector; automatically controlling an excitation source to generate one or more excitation pulses to excite the sample; collecting signal measurements of the monitoring light beam using the detector; determining an apparent change in transmission from a collected signal measurement in a presence of an excitation pulse and a collected signal measurement in an absence of an excitation pulse; automatically controlling the light shutter to block the monitoring light beam and prevent the monitoring light beam from interacting with the sample and proceeding to the detector; after controlling the light shutter to block the monitoring light beam, collecting a photo-event signal measurement based on an amount of light emitted from the sample following an excitation pulse without presence of the monitoring light beam; and determining an actual change in transmission by subtracting the photo-e
  • Clause 20 The method of clause 18, wherein the transient absorption spectra is generated for each wavelength specified by a user.

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  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

Spectromètre d'absorption transitoire (100) fournissant une correction de photo-événement en temps réel. Le spectromètre d'absorption transitoire (100) comprend une source d'excitation (102) pour produire des impulsions d'excitation pour exciter un échantillon (110), une source de lumière de surveillance (106) pour produire un faisceau de lumière de surveillance pour mesurer le spectre d'absorption transitoire de l'échantillon (110), et un détecteur (114) pour détecter la lumière, y compris des signaux du faisceau de lumière de surveillance. Le spectromètre d'absorption transitoire (100) comprend également un obturateur de lumière automatisé (108) pour empêcher le faisceau de lumière de surveillance d'interagir avec l'échantillon (110). En fonctionnement, l'obturateur (108) est commandé pour : (1) débloquer le faisceau de lumière de surveillance pour effectuer une mesure d'absorption transitoire qui comprend un signal de photo-événement ; et (2) bloquer le faisceau de lumière de surveillance pour mesurer le signal de photo-événement. Un spectre d'absorption transitoire corrigé est déterminé par soustraction de la mesure de signal de photo-événement à partir de la mesure d'absorption transitoire qui comprend un signal de photo-événement.
PCT/US2019/050228 2019-09-09 2019-09-09 Spectromètre d'absorption transitoire à correction de photo-événement WO2021050041A1 (fr)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018217997A1 (fr) 2017-05-24 2018-11-29 The Penn State Research Foundation Spectromètre d'absorption transitoire à la nanoseconde à taux de répétition de largeur d'impulsion court

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018217997A1 (fr) 2017-05-24 2018-11-29 The Penn State Research Foundation Spectromètre d'absorption transitoire à la nanoseconde à taux de répétition de largeur d'impulsion court

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