Second Derivative Infrared Spectroscopy

Abstract

The analysis of trace gases by infrared spectroscopy is enhanced by computing the second derivative of the spectrum. The peak maxima are increased for sharp bands while contributions from broad, structureless, continua are reduced. For weak absorbers the peak maxima are linear in concentration. The advantages of second derivative infrared spectroscopy in trace gas analysis are illustrated, and an algorithm is described for numerical differentiation of a digitized infrared spectrum.