Types of Raman technology: * * vibration Raman spectrum, surface enhanced Raman scattering, Fourier transform Raman spectrum, ultraviolet * * * vibration Raman spectrum and * * * focus micro Raman spectrum.
The function of Raman spectroscopy: it can mainly provide information about the surface structure of substances and can be used for qualitative and quantitative research.
Main limiting factors: At present, the key to restrict the wide application of Raman technology is fluorescence interference, and many new Raman technology changes are largely aimed at weakening or eliminating fluorescence interference in order to obtain high-precision, high-sensitivity and multifunctional Raman spectroscopy technology.
Brief introduction of Raman spectroscopy
Basic principles of 1. 1 Raman spectroscopy
Basic principles of Raman spectroscopy
Classical theoretical explanation: According to the classical theory of electromagnetic theory, the classical explanation of light scattering phenomenon is given here. The incident photon is inelastic scattered with the molecule, and the molecule absorbs the photon with the frequency of v0 and emits the photon of v-v0, and at the same time, the molecule moves from the low energy state to the high energy state-Stokes line. When the photon of v+v0 is emitted, the molecule moves from the high energy state to the low energy state, that is, the anti-Stokes line. This forms a weak Raman line near the strong Rayleigh peak. Because most molecules are in the ground state at room temperature, Stokes lines are often much stronger than anti-Stokes lines.
The unique advantages of 1.2 Raman spectroscopy in catalytic research
Both Raman spectrum and infrared spectrum can obtain the vibration and rotation spectra of molecules, and Raman activity will only occur when the polarizability of molecules changes. For infrared spectra, infrared activity can only be obtained when the dipole moment of molecules changes, so they are complementary to some extent, but they cannot replace each other.
Raman spectroscopy is superior to infrared spectroscopy under some experimental conditions, so Raman spectroscopy can give full play to its advantages in catalytic research:
1) can obtain the spectrum of low wavenumber region.
Generally, it is difficult to obtain the spectrum with low wavenumber (below 200cm- 1) in infrared spectrum, while Raman spectrum can even obtain the spectrum with dozens of wavenumbers. The low wavenumber spectral region reflects the structural information of the catalyst, especially the different structures of molecular sieves can be displayed in the low wavenumber spectral region.