Visible laser studies

Vj = 1 <— v" = 1 transition will be at a different energy than the Vj = 0 <— v" = 0. We use this fact to measure the vibrational spectrum of V (OCO) in a depletion experiment (Fig. 12a). A visible laser is set to the Vj = 0 Vj = 0 transition at 15,801 cm producing fragment ions. A tunable IR laser fires before the visible laser. Absorption of IR photons removes population from the ground state, which is observed as a decrease in the fragment ion signal. This technique is a variation of ion-dip spectroscopy, in which ions produced by 1 + 1 REMPI are monitored as an IR laser is tuned. Ion-dip spectroscopy has been used by several groups to study vibrations of neutral clusters and biomolecules [157-162]. 

In the case of the sulphur triimide S(NBu-f)3, the dispersive Raman technique applying a double monochromator and a CCD camera was employed to obtain the information from polarized measurements (solution studies) and also to obtain high-resolution spectra by low-temperature measurements. In the case of the main group metal complex, only FT-Raman studies with long-wavenumber excitation were successful, since visible-light excitation caused strong fluorescence. The FT-Raman spectra of the tetraimidosulphate residue were similar to those obtained from excitation with visible laser lines. 

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... 

As with terbium, a great deal of study has been made upon this ion in hopes of using it in a visible laser. Experiments along this line appear to have been very successful, and reports have been made on oscillation in crystals (757), glasses, and liquids (138). 

Studies at extremely high static pressure can be carried out in diamond anvil cells. Studies of chemical dynamics in gem anvil cells are beginning to be carried out, and some unique chemical synthesis can also occur at these high pressures. For example, a high pressure polymerized phase of carbon monoxide was recently reported to be synthesized using visible laser light to irradiate a carbon monoxide sample at pressures of over 5 GPa in a diamond anvil cell. ... 

In this paper, the authors present the results of studying of the structural and morphological changes that occur after UV and visible laser irradiation of layered organic-inorganic composites zinc and copper synthesized by laser ablation in liquid. The S5mthesized materials are the second and third group composites. Their structural formulas are as follows (M)2(OH)3X x z X H O and (M)(OH)2X x z x H O, where M - divalent metals (Zn, Cu) and X - intercalated anion - alkyl sulfate where n = 12. 

Raman spectroscopy is a vibrational spectroscopic technique which can be a useful probe of protein structure, since both intensity and frequency of vibrational motions of the amino acid side chains or polypeptide backbone are sensitive to chemical changes and the microenvironment around the functional groups. Thus, it can monitor changes related to tertiary structure as well as secondary structure of proteins. An important advantage of this technique is its versatility in application to samples which may be in solution or solid, clear or turbid, in aqueous or organic solvent. Since the concentration of proteins typically found in food systems is high, the classical dispersive method based on visible laser Raman spectroscopy, as well as the newer technique known as Fourier-transform Raman spectroscopy which utilizes near-infrared excitation, are more suitable to study food proteins (Li-Chan et aL, 1994). In contrast the technique based on ultraviolet excitation, known as resonance Raman spectroscopy, is more commonly used to study dilute protein solutions. 

The applications of visible laser Raman spectroscopy to monitor process-induced structural changes are illustrated in a study of the formation of transparent gels of whey... 

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