JP2010151839A - Heterodyne beat probe scanning probe tunnel microscope and method of measuring micro signal superimposed thereby on tunnel current - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heterodyne beat probe scanning probe tunnel microscope capable of easily and unfailingly detecting a weak RF signal, and a method of specifying a heterodyne beat signal by the scanning probe tunnel microscope. <P>SOLUTION: The scanning probe tunnel microscope includes a scanning tunnel microscope analyzing section for superimposing a given known externally superimposed reference high-frequency signal or externally superimposed reference electromagnetic signal on an unknown high-frequency signal or electromagnetic signal and causing quantum interference, wherein the externally superimposed reference high-frequency signal or externally superimposed reference electromagnetic signal is gradually approximated to the unknown high-frequency signal or the electromagnetic signal and is subjected to frequency sweeping to cause quantum interference, a tunnel current modulated by generating a heterodyne beat signal is generated from the quantum interference, and the unknown high-frequency signal or electromagnetic signal is detected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a scanning probe microscope, particularly a heterodyne beat probe high-frequency probe tunnel microscope, and a method for measuring a minute signal superimposed on a tunnel current.

  To date, spin-polarized tunneling electron microscopes (SP-STM) and near-field light microscopes (SNOM) have been developed for the purpose of electron spin detection.

  Patent Document 1 includes a step of applying a magnetic field to a sample, a step of irradiating the sample with a pulsed or continuous wave electromagnetic wave, and a step of detecting nuclear magnetic resonance of the sample. Is described from the change in the nuclear magnetic resonance signal of the sample.

In Patent Document 2, (a) a light source capable of controlling light intensity, (b) a driver of the light source, (c) an imaging interference optical system that forms an interference image from a sample on the imaging device surface, (D) a reference light phase modulator; (e) a driver of the phase modulator; (f) a controller of the imaging device; and (g) a computer that performs image processing and overall system control. as well as consideration of the higher order harmonics of the heterodyne beat signal on h) pixels, determined without depending the signal light intensity I _s the phase fluctuation component sigma, even if there is a random phase fluctuations, stable A heterodyne beat image synchronization measuring apparatus characterized by measuring a heterodyne beat image is described.

  Patent Document 3 describes obtaining an electric signal (beat signal) having a frequency that is the difference between the light emission frequencies of two light emitting elements.

  In Patent Document 4, in order to apply an ultrashort pulse high voltage between a probe of a scanning probe microscope and a sample, a DC or AC ultrashort pulse high voltage is applied to the coaxial cable from the pulse power source side, and the probe or sample is applied. The end of the coaxial cable is connected to either one of the terminals, and the other side is an ultrashort pulse high voltage application method in which the other end is substantially grounded so that the end of the coaxial cable can be regarded as an almost open end. The outer conductor of the coaxial cable is cut at the end and the core wire is projected as short as possible, the core wire is connected to either the probe or the sample, and voltage is reflected by power reflection at the coaxial open end. A method for applying an ultrashort pulse high voltage in a scanning probe microscope is described in which an ultrashort pulse high voltage with approximately doubled is applied between a short needle and a sample without distorting the waveform. ing.

JP 2005-156345 A JP 2002-214128 A JP-A-10-173602 JP-A-9-178759

  Spin-polarized tunneling electron microscopes (SP-STM) and near-field light microscopes (SNOM) have been developed for the purpose of electron spin detection. In SP-STM, spin-polarization is performed using a GaAs-based semiconductor as a probe. Since the carriers are generated, the resolution is only as high as the magnetization direction of the magnetic material. In optical SNOM, the Zeeman splitting of the electron orbit due to the application of the magnetic field, the spin selection rule between the transition orbits and the polarization direction thereof, etc. Although spin information has been obtained, spatial resolution at the atomic level cannot be obtained because a sharpened optical fiber is used for the probe. Therefore, an electron spin resonance experiment (ESR-STM) in which an RF signal analysis technique was incorporated into an STM apparatus with excellent spatial resolution was tried by Manasen et al. In Israel, but it is still spreading due to the difficulty in detecting minute signals. Absent. However, its importance has not changed, and the 10 GHz band microwave measurement technology, which has become easier to use with the recent development of communication technology, and the variable wavelength terahertz wave generation technology using laser light and optical comb are highly fused. The establishment of a highly accurate and stable RF-STM signal analysis technique is extremely significant.

  In view of such a point, the present invention is superposed on a heterodyne beat probe scanning probe tunnel microscope capable of easily and reliably detecting a minute signal, for example, a minute RF signal, and further superimposed on a tunnel current obtained by the scanning probe tunnel microscope. The purpose is to enable measurement of minute currents.

The present invention is a scanning probe tunnel microscope provided with a sharp probe as a probe, in which a tunnel current flowing between the probe facing the electron state of atoms / molecules on the sample surface and the sample is drawn,
An unknown high-frequency signal or electromagnetic wave signal is applied between the sample set on the scanning probe tunneling microscope and the probe to excite quantum vibration, and is intentionally varied. A known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal is provided, and is provided with a known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal applying means that is applied between the sample and the probe. A scanning tunneling microscope analysis unit that superimposes the external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal on the unknown high-frequency signal or electromagnetic wave signal to cause quantum interference, and the external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal is unknown It is asymptotic to the high-frequency signal or an electromagnetic wave signal, by frequency sweeping quantum interference Allowed, based on the quantum interference, to generate a modulated tunneling current due to rise to the heterodyne beat signal, provides a heterodyne beat probe scanning probe tunneling microscope and detects the unknown RF signals or electromagnetic signals To do.

The present invention also provides a heterodyne beat probe scanning probe tunnel microscope characterized in that the quantum interference is quantum interference that excites quantum resonance vibration of an unknown high-frequency signal or electromagnetic wave signal.
Further, according to the present invention, the scanning tunneling microscope analysis unit includes a magnetic field applying unit that applies a magnetic field to the sample, and makes the externally superimposed reference electromagnetic wave signal asymptotically approach an unknown electromagnetic wave signal, and sweeps the frequency to cause quantum interference. A heterodyne beat probe scanning probe tunneling microscope is provided.
The present invention also provides a heterodyne beat probe scanning probe tunnel microscope, wherein the external superimposed reference high-frequency signal or the external superimposed reference high-frequency signal and the external superimposed reference electromagnetic wave signal are optical beats.

The present invention also includes a spectrum analyzer that constitutes an excitation, reference, beat signal synthesizer unit, high stability reference signal transmitter and detection means connected to the scanning tunneling microscope analyzer, and the high stability reference signal transmission A heterodyne beat probe scanning probe tunnel microscope is provided in which the excitation, reference, beat signal synthesizer unit and spectrum analyzer are phase-synchronized by a reference signal from a machine to generate a heterodyne phase-synchronized detection signal.
The present invention also provides a heterodyne beat that generates a modulated tunnel current by generating a heterodyne beat signal based on quantum interference in a contact tunnel region where the probe contacts the sample surface. A probe scanning probe tunneling microscope is provided.

The present invention is a scanning probe tunnel microscope provided with a sharp probe as a probe, in which a tunnel current flowing between the probe facing the electron state of atoms and molecules on the sample surface and the sample is drawn,
An unknown high-frequency signal or electromagnetic wave signal is applied between the sample set on the scanning probe tunneling microscope and the probe to excite quantum vibration, and is intentionally varied. A known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal is provided, and is provided with a known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal applying means that is applied between the sample and the probe. A scanning tunneling microscope analysis unit that superimposes the external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal on the unknown high-frequency signal or electromagnetic wave signal to cause quantum interference is provided, and the external superimposed reference high-frequency signal or the external superimposed reference electromagnetic wave signal is unknown. Based on quantum interference with high-frequency signals or electromagnetic signals, the probe and sample A contact tunnel region in contact with the surface, which generates a modulated tunnel current by generating a heterodyne beat signal in the range of the surface depth in the range where the skin effect acts, and generates an unknown high-frequency signal or electromagnetic wave signal. To detect
  A heterodyne beat probe scanning probe tunneling microscope is provided.

The present invention also provides a heterodyne beat probe scanning probe tunnel microscope characterized by a surface depth range of 100 nm or less.

The present invention has a sharp probe as a probe, and measures a minute signal by a scanning probe tunneling microscope in which a tunnel current flowing between the probe and the sample facing the electronic state of atoms / molecules on the sample surface is drawn. In the method
A scanning tunneling microscope analysis unit applies an unknown high-frequency signal or electromagnetic wave signal between the sample set on the scanning probe tunneling microscope and the probe to excite quantum oscillations and to change the known An external superimposed reference high-frequency signal or an external superimposed reference electromagnetic wave signal is applied between the sample and the probe, and the given external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal is converted into an unknown high-frequency signal or electromagnetic wave. Asymptotic to signal, frequency swept to cause quantum interference, and based on the quantum interference, a modulated tunnel current is generated by generating a heterodyne beat signal, and an unknown high-frequency signal or electromagnetic wave signal is detected.
A method for measuring a minute signal using a heterodyne beat probe scanning probe tunneling microscope is provided.

The present invention has a sharp probe as a probe, and measures a minute signal by a scanning probe tunneling microscope in which a tunnel current flowing between the probe and the sample facing the electronic state of atoms / molecules on the sample surface is drawn. In the method
A scanning tunneling microscope analysis unit applies an unknown high-frequency signal or electromagnetic wave signal between the sample set on the scanning probe tunneling microscope and the probe to excite quantum oscillations and to change the known An external superimposed reference high-frequency signal or an external superimposed reference electromagnetic wave signal is applied between the sample and the probe, and the given external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal is converted into an unknown high-frequency signal or electromagnetic wave. Asymptotic to a signal, swept in frequency and caused quantum interference, and based on the quantum interference, the probe is a contact tunnel region in contact with the sample surface, in the range of the surface depth in the range where the skin effect acts Generate a modulated tunneling current by generating a heterodyne beat signal and detect unknown high-frequency or electromagnetic signals It provides a method for measuring small signal due to the heterodyne beat probe scanning tunneling microscope, characterized by.

  According to the present invention, a heterodyne beat probe tunnel scanning probe microscope capable of easily and reliably detecting a minute signal, for example, a minute RF signal, in order to use a known externally superimposed radio frequency signal or externally superimposed electromagnetic wave, Can provide a method for measuring a minute signal by specifying a heterodyne beat signal using this microscope.

  With the development of a scanning probe microscope (SPM) with excellent spatial resolution, the fine structure of the sample surface can be observed at the atomic scale, and the image of nanostructures such as semiconductor quantum dots and carbon nanotubes (CNT) It has been revealed in real space. Among them, the scanning probe tunneling electron microscope (STM) uses a sharp probe as a probe and the magnitude of the tunneling current drawn from the surface is proportional to the density of electronic states of atoms and molecules. It can be understood that it is expressed as a luminance signal on the XY coordinate plane based on the tunnel current which is the analysis main signal. At this time, in the conventional STM device, the tunnel current detection unit only supports direct current (DC) current, and thus only the information from the DC component has been handled.

  However, in reality, a minute high frequency (RF) current component is superimposed on the tunnel current due to external perturbation or stimulation, and this RF component has been overlooked so far. Here, if the detectable RF frequency of the tunnel current can be covered from microwave (centimeter wave to submillimeter wave) as electromagnetic wave in GHz band to terahertz wave (far infrared light) as light in THz band, microwave New observation targets include electron spin resonance (ESR) related to electron spin in the band, and lattice vibration and molecular rotation / vibration in the terahertz wave band. This means the creation of a new functional probe technology that physically elucidates the structure, physical properties, and reactions of materials produced by nanotechnology at the atomic level, and opens up a new field of spectroscopy of quantum electromagnetic waves. In other words, it has a wide range of fields in which the molecular spectroscopic basis of the invention is applied to medical applications and the like, and the results are extremely impactful.

  First, in ESR (ESR-STM) obtained through STM, physical properties of unpaired electrons and radicals existing near the surface can be obtained at the atomic level, so ESR-STM is not only used for research on magnetic materials and crystal defects. It is expected to provide an extremely important method in the study of surface science reactions such as surface oxidation, catalytic reaction, and molecular synthesis. Therefore, in the present embodiment, as an initial purpose, detection of a very weak RF signal (ESR frequency) existing in the microwave region in ESRSTM is performed by using an external superimposed reference signal (external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal) and an unknown spin. A device for interfering with a signal and generating a heterodyne beat signal as a result of the interference and a method for measuring a minute signal superimposed on a tunnel current are specified.

  Embodiments of the present invention will be described below with reference to the drawings.

  The drawing shows a heterodyne beat probe high-frequency scanning probe tunneling microscope 100 (hereinafter referred to as a scanning probe tunneling microscope. When high-frequency or / and electromagnetic waves are symmetric, they are referred to as a heterodyne beat scanning probe tunneling microscope). The scanning probe tunnel microscope 100 includes (1) a pre-amplification section for separating and amplifying a weak RF signal probed by an STM probe (probe), (2) a signal for reference with a spin vibration and a response analysis by a heterodyne method. It consists of three sections: generation section and (3) analysis section of frequency spectrum and RF transfer function vector. Details will be described below.

  The scanning probe tunnel microscope 100 includes a scanning tunnel microscope analysis unit 1, a scanning tunnel microscope analysis unit coupler 2, a heterodyne beat generation unit, that is, excitation, reference, beat signal synthesizer unit 3, highly stable reference signal transmitter 4, detection A spectrum analyzer and vector network analyzer 5, a pre-low noise high gain high frequency amplifier 6, and a high frequency separation unit 7 are provided.

  The scanning tunneling microscope analysis unit 1 includes a sample 11, a means 10 for applying a magnetic field to the sample, a sample 11 set on the SPM, and an STM probe (hereinafter referred to as a probe) 9 facing the sample. When a reference electromagnetic wave beat or an optical beat is flowed between the sample 11 and the probe 9 (irradiation), heterodyne occurs due to a nonlinear effect with a strong tunnel current, and a heterodyne beat signal is generated.

Figure 2 is a diagram showing the principle of the present invention, uses a scanning probe tunneling microscope 100 described above, FIG. 2 (a), the excitation nano-domains quantum vibrations from a known external superimposed reference frequency signal f ₂ and the sample was applied between the unknown high-frequency signal f ₁ samples 11 set in SPM to be (paragraph [0045] Referring) and sharp tip 9 opposite to the sample, it causes interference f ₂ to f ₁ It shows that the heterodyne beat signal f ₃ (= f ₁ ± f ₂ ) superimposed on the tunnel current is generated. f ₃ is based on the interference of the above, it is possible to identify immediately. FIG. 2B shows a state in which the known external superimposed reference high-frequency signal f ₂ and the unknown high-frequency signal f ₁ are applied between the sample 11 and the probe 9 from the outside. In this way it is possible to generate a heterodyne beat signal f _3. FIG. 2C shows a state in which f ₁ is supplied from the sample 11 and f ₂ is supplied from the probe 9 and applied between the sample 11 and the probe 9. FIG. 2 (d) shows a state where f ₂ is supplied to the sample 11, f ₁ is excited, and both are applied between the sample 11 and the probe 9. FIG. 2 (e) shows a state where f ₁ and f ₂ are applied from the horn 31 between the sample 11 and the probe 9. FIG. 2F shows a state where f ₁ and f ₂ are applied between the sample 11 and the probe from the irradiation point (final irradiation lens) 32 of the fiber optical system. The optical beats f ₁ and f ₂ sent by the fiber optical system are deflected and collimated, condensed by the irradiation converging lens, and irradiated.

  The probe 9 operates with respect to the sample 11 in the range from the non-contact tunnel region to the contact tunnel region. In the contact operation, non-linear characteristics are generated on the surface of the probe and the sample, regardless of the tunnel operation. That is, the tip position of the probe 9 is set in the heterodyne beat probe operating range from the non-contact region to the surface depth due to the high frequency skin effect. Therefore, the probe 9 operates in the heterodyne beat probe operation range from the non-contact region to the surface depth with respect to the sample 11.

  Specifically, the probe 9 is operated in the heterodyne beat probe operating range from the non-contact tunnel region to the surface depth of about 100 nm. A so-called electromagnetic wave such as horn electromagnetic wave irradiation, light irradiation, or contact needle injection is injected into the sample surface to excite surface plasmons and generate an electromagnetic field. For generation of this electromagnetic field, a method of flowing a surface current by bringing the space between the probe 9 and the sample 11 into contact with an electromagnetic wave can be adopted, and a minute signal is generated using a near field at the tip. become.

  In FIG. 1, a coupler 2 is configured so that a pseudo RF signal, which will be described later, is input to a sample 11 and an optical beat 8 can also be input.

  The coupling unit 2 is connected to an excitation, reference, and beat signal synthesizer unit 3, and the excitation, reference, and beat signal synthesizer unit 3 includes a high-frequency transmitter 12, a pulse transmitter 13, and a high-frequency mixed output selector 14. .

  The highly stable reference signal transmitter 4 transmits, for example, a high frequency of 10 MHz to the excitation, reference, and beat signal synthesizer 3 as a reference signal.

The high frequency separation unit 7 includes a high frequency pass filtering unit 21 and a low frequency pass filtering unit 22.
The high frequency signal detected by the scanning tunneling microscope analyzer 1 is filtered by the high frequency pass filter 21, and the low frequency signal is filtered by the low frequency pass filter 22. The filtered low frequency is converted into a corresponding current voltage by the scanning tunnel probe current-voltage converter 23, imaged by the scanning probe microscope 24, and displayed.

  The filtered high frequency (RF) is sent to a pre-low noise high gain high frequency band widther 6 for high frequency amplification.

  A graphite substrate as a sample is attached to the magnetic field applying means 10, and a high-frequency separation unit 7 in which a low-pass filter and a high-pass filter are inserted is placed immediately after the probe so as to separate the tunnel current into a DC component and an RF component, The separated DC component is guided to a scanning tunnel probe current-voltage converter 23 and a scanning probe microscope 24 that constitute a normal image analysis circuit, and an STM image of the graphite surface is displayed for observation.

  One RF component is sent to a pre-low noise high gain high frequency amplifier 6 (gain 45 dB) having a bandwidth of 100 KHz to 8 GHz, and after high frequency amplification, a spectrum analyzer for ESR-STM and a vector for high frequency device analysis Introduced into the analyzer 5.

  Then, a pseudo RF signal that simulates the detected RF signal is input from the high-frequency transmitter 12 to the sample through the high-frequency mixed output selector 14, and the tunnel current of the RF output signal component obtained therefrom is separated. As a result of inputting a known minute 2 GHz weak pseudo RF signal (-130 dBm) to the sample surface in the probe contact mode, as shown in FIG. 3, a dynamic range of 22 dBm and a resolution bandwidth from the spectrum analyzer having the above system configuration are shown. A value of 10 Hz was obtained. The noise level at room temperature is about -150 dBm at 2 GHz, and RF signal detection having an ESR frequency in the microwave band was performed by this system.

The optical beat 8 serving as an excitation source uses beat light in the THz band, and can be used as continuous light having a variable wavelength. Also, it known also diverted to the outside superimposed reference frequency signal f ₂ as a reference RF signal in a microwave band used for the measurement of ESR. The beat light is obtained by selecting and synthesizing two line spectra from a comb-shaped frequency comb generated by externally modulating continuous wave light and creating an optical pulse train. If the modulation frequency is adjusted and two line spectra are appropriately selected from the high frequency comb, beat signal light having an arbitrary frequency can be obtained. Since the characteristics of beat light synchronized in phase greatly affect the measurement result, it is important that the spectrum of the beat light is a so-called sharp peak having a narrow bandwidth with respect to the center frequency.

  In this way, a known external superimposed reference high frequency signal and an unknown high frequency signal are applied between the sample set in the SPM and the probe facing the sample, and the external superimposed reference high frequency signal interferes with the unknown high frequency signal. To generate a heterodyne beat signal. A known externally superimposed reference high frequency signal is used, and the heterodyne beat signal can be immediately identified. Thereby, the minute RF signal superimposed on the tunnel current can be detected.

  In the above example, an example in which a known external superimposed high-frequency signal is used has been described. However, a known external superimposed electromagnetic wave can be used. In this case, a known external superimposed reference electromagnetic wave signal and an unknown electromagnetic wave signal are applied between the sample set in the SPM and the probe facing this sample, and the unknown electromagnetic wave signal interferes with the external superimposed reference signal. Thus, a heterodyne beat signal is generated. As a result, electron spin resonance (ESR), which is a minute electromagnetic wave signal superimposed on the tunnel current, can be detected.

  The spectrum analyzer and vector network analyzer 5 are synchronized with the excitation, reference, and beat signal synthesizer unit 3.

  As described above, interference between the externally superimposed reference RF signal and the spin RF signal is performed, and the phase beat detection method is used as an example. By sweeping the frequency of the external superimposed reference RF signal, the external RF signal is driven to the thermal limit in order to efficiently operate the spectrum and vector analyzer of the spin RF signal, and the ratio of the carrier signal to noise (S / N ratio) is improved. It is desirable to do. Permanent magnets and electromagnetic magnets can be used as the magnetic field source for inducing the ESR state, and detection can also be performed by lock-in detection of an RF signal by magnetic field modulation. The principle of detection of the spin RF signal related to the surface magnetic atoms is generally understood as follows. Electrons of surface magnetic atoms placed in a static magnetic field cause spin precession due to the interaction of magnetic moments, but the tunnel current at this time is modulated from a few hundred MHz to a few GHz band depending on the magnetic field strength. As a so-called ESR signal, an RF signal having a frequency in the microwave band appears in a form superimposed on the DC tunnel current. In particular, since the electron spin source on the substrate surface interacts with the tunnel electron group of the metal probe, if the modulation of the tunnel current reflecting the ESR state coincides with the Larmor frequency, the electron spin source is localized in the vicinity of the tunnel region. Disturbances will occur and change the tunnel probability. By adding the terahertz wave beat 8 to the microwave radio wave technology, this extremely weak RF signal is captured, and a wide-band quantum electromagnetic wave spectroscopy with high spatial and wavelength resolution is established. It becomes possible to elucidate quantum physical properties in ultrafine structures such as substances and organic molecules.

Next, in terahertz spectroscopy using STM, information such as microscopic lattice vibration and molecular rotation / vibration can be obtained. The energy of terahertz waves changes the structure of biological macromolecules such as proteins and causes chemical reactions. This embodiment is effective. That is, biopolymers perform their functions while controlling and transforming weak bonds such as hydrogen bonds, van der Waals bonds, and hydrophobic bonds through thermal energy. Regarding the rotational spectrum of molecules, in fact, for light molecules, spectroscopy in the microwave band is not sufficient, and spectroscopy in the terahertz wave band is necessary. In this embodiment, since the spatial / wavelength resolution is particularly aimed at, the continuous operation optical beat 8 can be mainly used as an excitation source. However, if this portion is replaced with terahertz pulse light, time / space / wavelength A three-dimensional synergistic effect on three axes is obtained, and a chemical reaction approach from a new field of quantum electromagnetic spectroscopy becomes possible at the atomic and molecular level. For signal detection, the heterodyne phase beat detection method incorporated in the microwave band is applied to the terahertz wave band. Upon signal analysis, but using existing spectrum analyzer and vector analyzer 5, the detection method of weak microwave, so as to capture accurately the ESR signal of the RF frequency f _1, employing a phase beat technique. This intentionally superimposes an RF frequency f ₂ signal from an external circuit on the tunnel current between the STM probe and the sample surface, and pays attention to the interference effect of the signal frequencies f ₁ and f ₂ . When sweeping the frequency _{f 2} of the external superimposed reference RF signal, when _{f 2} is asymptotic to ESR frequency _{f 1,} with a decrease in the beat frequency _f 1 -f _2, amplified by a high gain f 1 -f ₂ component by heterodyne method Therefore, detection of the ESR signal frequency f ₁ can be realized on the frequency spectrum. The electromagnetic magnet, the applied magnetic field freely sweep, the relationship of the magnetic field strength B and the ESR frequency f _1, i.e. reveals magnetic field dependence of the spin precession. Further, the modulation frequency of the tunnel current by ESR can be changed by the sweep magnetic field, and the correlation with the Larmor frequency can be obtained. Furthermore, if a pulse magnetic field is applied to the electron spin in the ESR state in a direction that tilts the spin axis (parallel to the sample surface), the spin is transversely magnetized for a moment, and free induction decay of transverse magnetization is performed as the pulse response. Happens. By observing this decay process and the change in the tunnel current, the relationship between the ESR state and the tunnel current modulation is also clarified. On the other hand, the aerial radiant energy of the RF signal is extremely small under matching conditions due to the skin effect, but application of a lateral pulse magnetic field from the outside as described above works in a direction that disturbs the matching conditions, and the modulated RF signal intensity is Increase.

  Heterodyne beat probe technology has been made possible to work with SPM spectrometers. A wide range of multi-channel RF spectrometers were mounted on the SPM along with the magnetic field modulator without losing the conventional SPM imaging function. The analysis frequency range has a section unit structure, and has a beat wavelength shift function capable of supporting a very wide frequency band by setting the unit to a corresponding analysis frequency. Connection with an existing optical distribution device such as absorption spectroscopy at the optical wavelength level is also possible by coupling an optical beat probe in the SPM of this embodiment, and microwave spectroscopy is performed by receiving irradiation of an existing optical beat signal source. It is a possible basic mainframe (optical beat probe spectroscopic receiver). Thus, the radio wave boundary region (both are electromagnetic waves) in the THz region is also covered as the spectral region. Further, a millimeter wave THz wave is generated by the optical beat. When the sample is RF excited or in the ESR state, the surface electronic state changes, so the corresponding SPM image can be observed in the existing tunnel current image. In this case, without reflecting the existing SPM performance in imaging reflecting the surface electronic state caused by excitation absorption, a spectral signal is added to an SPM image having an SPM basic frame structure capable of performing microwave spectroscopy with SPM. A map can be formed.

The beat includes demodulation formats such as AM, FM, PM, SSB, and PWM of all modulation formats that are the core of radio wave communication technology such as comb and phase modulation, and constitutes a modulation beat probe that demodulates signals from the nano region, Radio communication technology, including extremely high-level light, provides an SPM that forms the core of the device. The beat source of f ₁ and f ₂ is not limited to 2 channels, and a programmable synthesizer operation as a new spectroscopic radiation source having a structure capable of injecting an n-channel beat into the quantum region, and not operating only with a beat signal source By combining with SPM, it functions as an SPM microwave spectrometer. As for the beat irradiation injection, the inter-probe sample injection is the RF near field probe circuit sample contact probe (cat whiskers) space irradiation (with bias control) and the optical beat is also an electromagnetic wave, so that the spatial convergence irradiation method can be used. In order to reduce the size of the device, the waveguide uses a fiber optic system for optical communication, and enables collimation convergence and deviation control. Further, it is possible to irradiate the sample surface with a directional beam using a coupler, and the optical gain can be freely set by a 1.55 micron optical amplifier.

  For the delay, a biased surface controller and fiber delay are used. The microwave submillimeter wave THz wave broadband wavelength band has many common points in communication engineering, and the SPM and the beat probe are combined. Vector interference detection also operates with microwave technology as a substrate. Optical microwave conversion is used, and the vibration analysis at the optical level is converted to wavelength and performed by the microwave spectroscopy technique. The sensitivity of the receiver is realized by the triple superheterodyne method and the very low noise high gain first stage circuit. Physical properties can be explored by interference of quantum electromagnetic waves at shallow surface depths. Spin labeling signals for ESR observation with nanoparticles such as dielectrics and magnetics attached to proteins can be obtained from microwave excitation reference lines and signals from fine regions. The interference beat signal is obtained by vector analysis. In this way, the physical properties of the fine structure can be evaluated. From the skin effect peculiar to the RF current and the magnetic field modulation, it is possible to obtain knowledge of signals from the magneto-optical device thin film superlattice fine particles such as spin waves.

  The heterodyne beat probe movement range is set from the characteristics of RF by SPM's Z-axis approach to the tunnel phenomenon that operates beyond the tunnel region, the tunnel region and the half contact region interface tunnel, the insulator thin film, and the Gieber tunnel. Can be done. It is also possible to excite a minute region at a depth of several tens of nanometers from the surface, and it is possible to handle a quantum dot-related resonant RF signal such as a quantum vortex or a quantum dot. The injection signal, spectrum analyzer, and vector network analyzer analyzer are provided in the SPM as a radio wave spectroscopic interferometer locked with a reference signal. It is possible to observe the interference at the same time directly under the probe or to generate the programmed interference, enabling the fine structure analysis and the fine structure excitation control at the same time. All quantum effect signals are radiated to nature as extremely weak electromagnetic waves near the thermal noise limit. These weak signals can be captured by SPM. In addition, it is possible to generate multiple resonance states by beat-injecting electromagnetic waves in the same frequency region into the nano region in a coherent manner and exciting the nano region quantum vibrations by molecular vibration lattice vibrations and various tunneling phenomena. .

  SPM spectral image spectroscopy, control of various surface electronic states, and control of chemical reactions can be performed directly under the probe. These are operated by making effective use of nonlinear effects and nonlinear phenomena with strong tunneling current. The sensitivity is -150 dBm at (300 K) in the GHz region by effectively utilizing the nonlinear effect and the nonlinear phenomenon with strong tunnel current.

  If the magnetic field modulation is performed at high speed, the spin response is loaded on the RF absorption spectroscopy, and the fine structure spectroscopy and the vibration control can be performed by the SPM with high resolution. In ESR, new ESR spectroscopy in which optical ESR and millimeter wave ESR coexist is possible, and new resonance spectroscopy is possible in a fine region. High-frequency technology and optical technology cultivated in optical communications Coherent optical multiplex communication technology can be extended to the radio wave boundary region THz region. It is an SPM coupled to a beat probe and can be used for spectroscopic analysis in the field of life phenomena and environmental science.

  Recent advances in nanotechnology have created highly functional semiconductor quantum dots, metal superlattices, and organic molecules in various forms, and their structures and physical properties have been investigated. However, in terms of extreme measurement, the physical properties of atomic-scale single structures were unexplored. In this embodiment, the current detection unit of a scanning probe microscope with excellent spatial resolution is made possible by evolving from DC support to RF support, and spin information of unpaired electrons in the microwave band obtained therefrom is obtained. The molecular vibration spectrum of the terahertz band is extremely important in both natural science and environmental life science. The establishment of this RF signal analysis technology includes a wide range of applications in engineering, medicine, pharmacy, etc. ing. This was made possible for the first time as a result of a high degree of fusion between microwave radio technology and optical technology in the infrared region, based on recent developments in communication technology. For example, if the RF-ESR signal in the microwave band can be evaluated and analyzed at the single atom / molecular level by STM, all phenomena related to electron spin can be grasped meaningfully, which is indispensable for an advanced information society. It can be applied not only to the development of density magnetic recording elements but also to the observation of the structure of biological radicals and the specificity of reactions in the bio field, and has a wide field of view.

The block diagram of the Example of this invention. The figure which shows the function example of a scanning tunnel microscope analysis part. Experimental result figure.

  DESCRIPTION OF SYMBOLS 1 ... Scanning tunnel microscope analysis part, 2 ... Coupler, 3 ... Excitation, reference, beat signal synthesizer part, 4 ... High stability reference standard signal transmitter, 5 ... Spetram analyzer and vector network analyzer, 6 ... Pre-low Noise high gain high frequency amplifier, 7 ... high frequency separator, 8 ... optical beat, 10 ... magnetic field applying means, 11 ... sample, 12 ... high frequency transmitter, 13 ... pulse transmitter, 14 ... high frequency mixed output selector (mixer), 100: Heterodyne beat probe scanning probe tunnel microscope (scanning probe tunnel microscope, heterodyne beat probe high-frequency probe tunnel microscope).

Claims (10)

A scanning probe tunnel microscope that has a sharp probe as a probe and that draws a tunnel current flowing between the probe and the sample facing the electron state of atoms and molecules on the sample surface,
An unknown high-frequency signal or electromagnetic wave signal is applied between the sample set on the scanning probe tunneling microscope and the probe to excite quantum vibration, and is intentionally varied. A known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal is provided, and is provided with a known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal applying means that is applied between the sample and the probe. A scanning tunneling microscope analysis unit that superimposes the external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal on the unknown high-frequency signal or electromagnetic wave signal to cause quantum interference, and the external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal is unknown It is asymptotic to the high-frequency signal or an electromagnetic wave signal, by frequency sweeping quantum interference Allowed, based on the quantum interference, to generate a modulated tunneling current due to rise to the heterodyne beat signal, the unknown RF signal or the heterodyne beat probe scanning probe tunneling microscope and detecting an electromagnetic wave signal. 2. The heterodyne beat probe scanning probe tunnel microscope according to claim 1, wherein the quantum interference is quantum interference that excites quantum resonance vibration of an unknown high-frequency signal or electromagnetic wave signal. 2. The scanning tunneling microscope analysis unit according to claim 1, further comprising: a magnetic field applying unit that applies a magnetic field to the sample, wherein the externally superimposed reference electromagnetic wave signal is asymptotic to an unknown electromagnetic wave signal, and the frequency is swept to cause quantum interference. A heterodyne beat probe scanning probe tunnel microscope. 2. The heterodyne beat probe scanning probe tunnel microscope according to claim 1, wherein the external superimposed reference high-frequency signal or the external superimposed reference high-frequency signal and the external superimposed reference electromagnetic wave signal are optical beats. 2. The high stability reference signal transmitter according to claim 1, further comprising: a spectrum analyzer that constitutes excitation, reference, beat signal synthesizer, high stability reference signal transmitter and detection means connected to the scanning tunneling microscope analyzer. A heterodyne beat probe scanning probe tunneling microscope characterized in that the excitation, reference, beat signal synthesizer unit and spectrum analyzer are phase-synchronized by a reference signal from the signal to generate a heterodyne phase-locked detection signal. 2. The heterodyne beat probe according to claim 1, wherein a modulated tunnel current is generated by generating a heterodyne beat signal based on quantum interference in a contact tunnel region where the probe contacts the sample surface. Scanning probe tunnel microscope. A scanning probe tunneling microscope comprising a sharp probe as a probe, in which a tunnel current flowing between the probe and the sample facing the electronic state of atoms and molecules on the sample surface is drawn,
An unknown high-frequency signal or electromagnetic wave signal is applied between the sample set on the scanning probe tunneling microscope and the probe to excite quantum vibration, and is intentionally varied. A known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal is provided, and is provided with a known external superimposed reference high-frequency signal or external superimposed electromagnetic wave signal applying means that is applied between the sample and the probe. A scanning tunneling microscope analysis unit that superimposes the external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal on the unknown high-frequency signal or electromagnetic wave signal to cause quantum interference is provided, and the external superimposed reference high-frequency signal or the external superimposed reference electromagnetic wave signal is unknown. Based on quantum interference with high-frequency signals or electromagnetic signals, the probe and sample A contact tunnel region in contact with the surface, which generates a modulated tunnel current by generating a heterodyne beat signal in the range of the surface depth in the range where the skin effect acts, and generates an unknown high-frequency signal or electromagnetic wave signal. To detect
  Heterodyne beat probe scanning probe tunnel microscope characterized by. 8. The heterodyne beat probe scanning probe tunnel microscope according to claim 7, which has a surface depth range of 100 nm or less. In a method of measuring a minute signal by a scanning probe tunnel microscope, which has a sharp probe as a probe and draws a tunnel current flowing between the probe and the sample facing the electronic state of atoms and molecules on the sample surface,
A scanning tunneling microscope analysis unit applies an unknown high-frequency signal or electromagnetic wave signal between the sample set on the scanning probe tunneling microscope and the probe to excite quantum oscillations and to change the known An external superimposed reference high-frequency signal or an external superimposed reference electromagnetic wave signal is applied between the sample and the probe, and the given external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal is converted into an unknown high-frequency signal or electromagnetic wave. Asymptotic to signal, frequency swept to cause quantum interference, and based on the quantum interference, a modulated tunnel current is generated by generating a heterodyne beat signal, and an unknown high-frequency signal or electromagnetic wave signal is detected.
A method for measuring minute signals using a heterodyne beat probe scanning probe tunneling microscope. In a method of measuring a minute signal by a scanning probe tunnel microscope, which has a sharp probe as a probe and draws a tunnel current flowing between the probe and the sample facing the electronic state of atoms and molecules on the sample surface,
A scanning tunneling microscope analysis unit applies an unknown high-frequency signal or electromagnetic wave signal between the sample set on the scanning probe tunneling microscope and the probe to excite quantum oscillations and to change the known An external superimposed reference high-frequency signal or an external superimposed reference electromagnetic wave signal is applied between the sample and the probe, and the given external superimposed reference high-frequency signal or external superimposed reference electromagnetic wave signal is converted into an unknown high-frequency signal or electromagnetic wave. Asymptotic to a signal, swept in frequency and caused quantum interference, and based on the quantum interference, the probe is a contact tunnel region in contact with the sample surface, in the range of the surface depth in the range where the skin effect acts Generate a modulated tunneling current by generating a heterodyne beat signal and detect unknown high-frequency or electromagnetic signals Be
A method for measuring minute signals with a heterodyne beat probe scanning tunneling microscope.

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