STM needle tip enhanced spectrum acquisition device and acquisition method thereof

Abstract

The invention provides an STM needle tip enhanced spectrum acquisition device and method, and the method comprises the steps of: S1, enabling a test sample to be horizontally moved, and enabling a laser device to emit pulse laser to focus on the surface of the test sample so as to form a circular or elliptical light spot; S2, driving a needle point piezoelectric displacement table through a driving signal to drive an STM needle point to perform step type displacement motion perpendicular to the center of the light spot, and triggering a frequency multiplier to output a double-frequency pulse signal to a spectrograph, thus enabling the driving signal to synchronously trigger the spectrograph at a rising edge and a falling edge respectively; S3, collecting spectral signals induced on the surface of the test sample by a spectrograph when the STM needle point is located at the lowest point and the highest point in a motion period; and S4, carrying out subtraction processing on the two spectral signals acquired in each motion period through a signal acquisition system to obtain subtraction spectrums, and carrying out linear superposition based on the plurality of subtraction spectrums to obtain a spectrum without background signals. According to the invention, background light signals can be eliminated, and extraction of enhanced light signals is realized.

Description

technical field [0001] The invention relates to the technical field of atomic-weight resolution spectral imaging, in particular to an enhanced spectrum acquisition device based on periodic displacement of an STM needle tip and an acquisition method thereof. Background technique [0002] Scanning Tunneling Microscope (STM) can detect the electron distribution of materials at the atomic level and obtain super atomic-scale spatial resolution capabilities. It provides useful information for understanding and mastering single molecules, nanostructures and low-dimensional materials. Provide a powerful means for understanding nanoscale electronic states and quantization effects. The tip of the STM probe is generally made of noble metal, and has a very small radius of curvature. Under the induction of the laser, it can localize the plasma on the surface of the measured material, and generate needle-tip-enhanced fluorescence and Raman scattering on the surface of the tested material....

AI Technical Summary

Problems solved by technology

Such a design cannot improve the signal-to-noise ratio of the part of the light signal enhanced by the needle tip, so the current technical test objects or the reported research work can only target a single type of molecule, and they are placed on a substrate that can eliminate the background For example, a thin layer of NaCl is epitaxially deposited on the gold film to eliminate the fluorescence background of the gold plasma effect.

If you are facing a material system with light scattering or fluorescence background, such as fluorescence or Raman in the point defect region of a semiconductor film, the existing technology cannot effectively extract the needle tip enhanced light signal, because the light emission and light scattering of the semiconductor material itself Very strong, because the ratio of the number of atomic groups under the effective area of ​​the needle tip to the number of atomic groups under the irradiated surface of the laser beam spot is 10 -8 Above, the part of the needle tip enhanced optical signal will be greatly affected by the background of the laser irradiation surface

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