public class RamanShift
extends java.lang.Object
Raman scattering is a powerful light scattering technique used to diagnose the internal structure of molecules and crystals. In a light scattering experiment, light of a known frequency and polarization is scattered from a sample. The scattered light is then analyzed for frequency and polarization. Raman scattered light is frequency-shifted with respect to the excitation frequency, but the magnitude of the shift is independent of the excitation frequency. This "Raman shift" is therefore an intrinsic property of the sample.
Because Raman scattered light changes in frequency, the rule of conservation of energy dictates that some energy is deposited in the sample. A definite Raman shift corresponds to an excitation energy of the sample (such as the energy of a free vibration of a molecule). In general, only some excitations of a given sample are "Raman active," that is, only some may take part in the Raman scattering process. Hence the frequency spectrum of the Raman scattered light maps out part of the excitation spectrum. Other spectroscopic techniques, such as IR absorption, are used to map out the non-Raman active excitations.
Additional information, related to the spatial form of the excitation, derives from the polarization dependence of the Raman scattered light. The shape of an excitation in a material, for example a vibration pattern of the atoms in a molecule, and the polarization dependence of the scattering, are determined by the equilibrium structure of the material through the rules of group theory. By this route one gleans valuable and unambiguous structural information from the Raman polarization dependence.
National Institue of Standards and Technology NIST, Physics Laboratory, (Online: September 2000, Last updated: March 2002), http://physics.nist.gov/Divisions/Div844/facilities/raman/Ramanhome.html (page no longer available)
Constructor and Description |
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RamanShift() |
Modifier and Type | Method and Description |
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static double[] |
processSpectrum(double[] wavelengths,
double laserWavelength)
This method converts wavelengths (nm) into Raman Shift
using the laser wavelength (nm) parameter.
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public static double[] processSpectrum(double[] wavelengths, double laserWavelength)
wavelengths
- the array of wavelengths to calculate the Raman Shift.laserWavelength
- the laser wavelength in nm used in calculating
Raman Shift.Copyright 2004-2006 Ocean Optics, Inc. All Rights Reserved.