Raman spectroscopy applications of an imaging photomultiplier tube

Abstract

A Raman spectroscopy system having an unprecedented combination of high sensitivity and low noise has been built incorporating an imaging (2-D) photomultiplier tube. The number of photons detected for a vibrational band approaches the theoretical limit set by the Raman cross section and experimental configuration. A detector dark count of 10⁻⁴ counts/s/pixel is the major electronic source of noise. The spectrum of air reveals low concentration gas components, specifically ¹⁶O¹⁸O and CO₂. Vibrational Raman spectra are obtained from solid samples as thin as 20 nm with low laser powers, e.g., 6.5 mW. The imaging photomultiplier yields 1-D (along the focused laser beam) Raman images of interfaces or concentration gradients.

© 1987 Optical Society of America

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