Low-resolution Raman spectroscopy

LAMMA Laser microprobe mass analysis (see LRRS Low-resolution Raman spectroscopy... 

C. Mello, E. Severi, L. Coelho, A. Marangoni, C. Dezuane, E. Ricci, D. Ribeiro and R.J. Poppi, Two-dimensional low resolution Raman spectroscopy applied to fast discrimination of microorganisms that cause pharyngitis a whole-organism fingerprinting approach, J. Mol. Struct, 883-884, 61-65 (2008). 

T.R. McCaffery and Y.G. Durant, Apphcation of low-resolution Raman spectroscopy to onhne monitoring of miniemulsion polymerization, J. Appl. Polym. Sci., 86, 1507-1515 (2002). 

McCaffery, T.R. 8c Durant, Y.G. Application of Low-Resolution Raman Spectroscopy to Online Monitoring of Miniemulsion Polymerization /. Appl. Polym. Sci. 2002, 86, 1507-1515. 

R. H. Clarke, S. Londhe, W. R. Premasiri, and M. E. Womble, Low-resolution Raman spectroscopy Instrumentation and applications in chemical analysis, J. Raman Spectrosc. 30,827 (1999). 

Clarke et al. [16] has shown that low-resolution Raman spectroscopy (LRRS) can be combined with surface-enhanced Raman spectroscopy (SERS) for the determination of cyanide in water. The enhanced characteristic band of CN at 2134 cm is so prominent and is located in a portion of the spectral band, normally not populated by peaks from other organic compounds. The much lower cost LRRS spectrometer can be used to detect the presence of CN at these trace level concentrations. T e sample consisted of a solution of 2-3 mL of the different sizes of gold colloid (5, 10, and 20 mn. Sigma chemical company) with 1-2 mL of cyanide samples, mixed at room temperature and SERS spectra were recorded from this mixture to detect trace amounts of cyanide. 

Principles and Characteristics The main drawback to Raman has been its high price tag relative to mid-IR and near-IR, although the price barrier to Raman is lessening. Nevertheless, a main issue is still the laser system required to produce quality high-resolution spectra. Clarke et al. [445] have recently introduced the concept of low-resolution Raman spectroscopy (ERRS) as a potentially highly useful, low-cost approach to organic identification and analysis. 

C. Mello, D. Ribeiro, F. Novaes and R. J. Poppi, Rapid differentiation among bacteria that cause gastroenteritis by use of low-resolution Raman spectroscopy and PLS discriminant analysis. Analytical Bioanalytical Chemistry, 2005, 383(4), 701-706. 

A number of model in situ and on-site apphcations of low resolution, and therefore low cost, Raman spectroscopy have been reported including the quantitative monitoring of synthetic rubber and polystyrene emulsion polymerisations, detection of illicit drugs and explosives and detection of cyanide in wastewater using a surface enhanced Raman system [26]. 

Local analysis can be carried out only by the LIF and CARS methods. They have the highest time resolution. The CARS method or any other method of Raman spectroscopy are imiversal but have low sensitivity. Therefore, it is reasonable to use resonance Raman spectroscopy because its sensitivity is higher. Due to a low sensitivity, Raman spectroscopy is combined with a pulse source of generation of active... 

The best resolution of Q-branch rotational structure in a N2-Ar mixture was achieved by means of coherent anti-Stokes/Stokes Raman spectroscopy (CARS/CSRS) at very low pressures and temperatures (Fig. 0.4). A few components of such spectra obtained in [227] are shown in Fig. 5.9. A composition of well-resolved Lorentzian lines was compared in [227] with theoretical description of the spectrum based on the secular simplification. The line widths (5.55) are presented as... 

The other vibrational spectroscopies, laser Raman and magic angle spinning NMR, have also been useful. Despite its low resolution, high resolution EELS has been usefiil in UHV work for assessment of surface cleanliness and for the identification of adsorbed species. 

One of the main advantages of CARS and also of other nonlinear Raman spectroscopies is the high resolution that can be achieved in spectra of gases at low pressures. The reason for this is that the instrumental resolving power in these techniques depends only on the convoluted linewidths of the lasers used for excitation, whereas in linear Raman spectroscopy the resolution is determined by the monochromators used to disperse the observed scattered Raman light. 

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