Introduction of Instrument

Laser confocal micro Raman spectroscopy is a non-destructive micro-area analysis method that combines two techniques of Raman spectroscopy and microscopic imaging to analyze molecular structure, composition of matter, and conformational morphology by studying the characteristics of Raman spectral changes of substances. It is mainly composed of laser light source, sample device, filter, monochromator, microscope system and detector, etc.

This instrument is equipped with three different wavelength excitation light sources of 532nm, 633nm and 785nm, which can adapt to most of the samples for Raman testing. In addition to conventional single-spectrum acquisition, it can also perform depth scanning, surface imaging and body imaging of samples to obtain information on the distribution of different components in samples at different depths, in different areas of the surface and within a certain volume; in addition, its real-time focus imaging system can maintain focus during dynamic measurements, which is suitable for surface Raman imaging of rough and dynamic samples.

Working Principle

When light hits a sample, the incident laser causes the molecules (or lattice) to vibrate and lose (or gain) some energy, resulting in a change in the frequency of the scattered light, which is analyzed by Raman spectroscopy, The analysis of scattered light is called Raman spectroscopy. The analysis of Raman spectroscopy can be used to find out the components, structure and relative content of molecules, so it has become a basic technical tool for the structural.

The basic process of Raman testing: the sample is excited by a specific wavelength laser to produce Raman scattering, which passes through a series of optical circuit elements and reaches the detector, and the computer processes it to get the corresponding Raman spectrum.

Sample Preparation

★Sample requirements: powder solids, paste solids, liquids, colloids and almost all substances containing real molecular bonds are suitable for Raman spectroscopy analysis, combined with the requirements for the use of microscope, usually the surface of the sample to be measured should be smooth and flat.

★Solid samples: powdered samples can be taken in small amounts on clean slides or silicon wafers and pressed into a smooth plane (to ensure that the powder cannot float everywhere), or dispersed into the solvent and dropped onto the slides; block samples can be made into a smooth plane on one side of the sample; films, fibers, coatings, etc. can be tested directly on their smooth sides.

★Liquid samples: 1-2 drops can be sucked onto a clean slide with a dropper, where volatile or highly corrosive samples need to be tested with a coverslip on the liquid or by inhaling the capillary tube and sealing it.

Photograph: Jiang Xuejie, 2022 master-Zhang Peng team

Montage: Jiang Xuejie, 2022 master-Zhang Peng team