Raman spectroscopy visible-light excitation

Raman spectroscopy detects the scattering of light, not its absorption. Superposed on the frequency of the scattered light are the frequencies of the molecular vibrations. The detection occurs in the IR spectral region while the excitation happens in the visible region. Since laser light sources have become well developed, Raman spectroscopy has become an important tool for the analysis of biomolecules. 

A number of cyano-bridged complexes are included here even though they strictly do not fall in the general family-type defined for the section. The syntheses and photophysical properties of [(NC)(bpy)2Ru(/r-NC)Cr(CN)5] and [(NC)5Cr(Ai-CI Ru(bpy)2(M-NC)Cr(CN)5] have been described. Absorption of visible light by the Ru(bpy)2 unit results in phosphorescence from the Cr(CN)g luminophore, and the results evidence fast intramolecular exchange energy transfer from the MLCT state of the Ru(bpy)2 chromophore to the doublet state of the Cr -based unit. Time-resolved resonance Raman and transient UV-vis absorption spectroscopies have been employed to investigate the MLCT excited states of [(NC)(bpy)2Ru(//-CN)Ru (bpy)2(CN)], [(NC)(bpy)2Ru(//-CN)Ru(phen)2(CN)]+, [(NC)(phen)2Ru(//-CN)Ru (bpy)2(CN)]+, [(NC)(bpy)2... 

Room temperature ILs have been the object of several Raman spectroscopy studies but often ILs emit intensive broad fluorescence. In our own experiments, the use of visible laser light (green 514.5 nm or red 784 nm) resulted in strong fluorescence [29,46]. Similar observations have been reported for many IL sysfems. Our experimental spectra needed to be obtained by use of a 1064 nm near-IR exciting source (Nd-YAC laser at 100 mW of power). The scattered light was filtered and collected in a Bruker... 

Section 2.3). The scattered light consists of two types one, called Rayleigh scattering, is strong and has the same frequency as the incident beam (vo), and the other, called Raman scattering, is very weak ( 10 5 of the incident beam) and has frequencies vo vm, where vm is a vibrational frequency of a molecule. The vo — vm and vo + vm lines are called the Stokes and anti-Stokes lines, respectively. Thus, in Raman spectroscopy, we measure the vibrational frequency (vm) as a shift from the incident beam frequency (vo). In contrast to IR spectra, Raman spectra are measured in the UV-visible region where the excitation as well as Raman lines appear. 

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