| CPC G01Q 20/02 (2013.01) | 12 Claims |
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1. A single-molecule force spectroscopy-infrared spectroscopy (SMFS-IR) coupling system, comprising:
an optical path system module configured to utilize a microcantilever to sense and amplify an interaction force between a sharp tip on a cantilever and a polymer molecule under test, to obtain and send a deflection signal of the microcantilever;
a lock-in amplifier connected to the optical path system module and configured to calculate a resonance frequency from the deflection signal through fast Fourier transform (FFT);
a processor module connected to the lock-in amplifier and configured to assign the resonance frequency as a pulse repetition frequency to a signal generator;
the signal generator connected to the processor module and configured to:
generate co-frequency electrical signals based on the pulse repetition frequency;
transmit the co-frequency electrical signal as a trigger signal to an infrared laser in the optical path system module; and
transmit the co-frequency electrical signal as a reference signal to the lock-in amplifier; and
a photothermal detector connected to the infrared laser in the optical path system module and the lock-in amplifier and being configured to:
convert a received laser intensity into laser power when collecting background data of the infrared laser; and
transmit the laser power to the lock-in amplifier, wherein the lock-in amplifier transmits the laser power to the processor module;
the lock-in amplifier is further configured to: demodulate the deflection signal of the microcantilever according to the reference signal, obtain a microcantilever amplitude, and transmit the microcantilever amplitude to the processor module, wherein the microcantilever amplitude represents original spectrum data; and
the processor module obtains an amplitude-wavenumber curve according to the microcantilever amplitude and the laser power; divides the amplitude-wavenumber curve by the background data of the infrared laser, and performs gain adjustment according to a radiation intensity of the infrared laser at each wavenumber segment, to obtain SMFS-IR data of a sample under test; wherein the original spectrum data is collected when the sharp tip is connected to a target molecule of the polymer molecule under test; after the collection is completed, the target molecule is ruptured, and the sharp tip is controlled to move to a position for spectral signal collection, to collect signals again and obtain a pure photoacoustic noise;
the original spectrum data and the pure photoacoustic noise are normalized, and subtraction is performed to obtain the SMFS-IR data with the photoacoustic noise removed;
after the sharp tip is connected to the target molecule of the polymer molecule under test, a first clamping force is preset; when a force on the sharp tip reaches the first clamping force, a process of moving the sharp tip away is stopped, and the sharp tip is held in place;
during a holding phase, the sharp tip performs intervention of an infrared laser light and collects infrared spectrum data;
after completing the collection of the infrared spectrum data, the sharp tip continues to move away from the target molecule of the polymer molecule under test until the target molecule is ruptured; and
for a target molecule with mechanochemical response, an M-level clamping force is preset after the sharp tip is connected to the target molecule of the polymer molecule under test, specifically comprising:
when the force on the sharp tip reaches the first clamping force and the sharp tip undergoes a first holding phase, continuing operation steps of a second stretching phase and a second holding phase; if a mechanochemical reaction is triggered during the second stretching phase, setting a second clamping force during the second holding phase to be equal in magnitude to the first clamping force during the first holding phase; and
performing, by the sharp tip, intervention of the infrared laser light and collecting the infrared spectrum data during both the first holding phase and the second holding phase, to obtain an in situ mechanochemical identification result.
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