Effects of sample heating in FT-Raman spectra of biological materials

N. A. Marigheto, E. K. Kemsley, J. Potter, P. S. Belton, R. H. Wilson

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Abstract

The effects of laser-induced sample heating and fluorescence of biopolymers in Fourier transform-Raman spectroscopy were investigated. It was shown that these two phenomena are essentially independent of each other. Methods of quantifying the laser-induced heating were developed and it was shown that measurement of the thermal emission generated by the sample is not sufficient to determine its temperature. The use of a marker compound mixed with the test sample to estimate the sample temperature was explored. Monitoring the temperature-dependent phase transitions of NH4NO3 provided a crude indication of a minimum sample temperature. However, using sulphur as a marker and exploiting the relationship between the intensities of its anti-Stokes and Stokes bands, it was possible to estimate the sample temperature with greater confidence. Using these techniques it was shown that sample temperatures could easily reach approximately 400 K under normal laser power inputs. Such temperatures are likely to be damaging to biological samples and it is concluded that great care must be exercised when using FT-Raman.
Original languageEnglish
Pages (from-to)1571-1579
Number of pages9
JournalSpectrochimica Acta - Part A Molecular Spectroscopy
Volume52
Issue number12
DOIs
Publication statusPublished - 15 Nov 1996

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