Thermal emission decay Fourier transform infrared spectroscopy

We present a new technique, thermal emission decay Fourier transform infrared spectroscopy, designed to perform noninvasive, noncontacting absorption spectrum measurements on unprepared, arbitrary surfaces. It uses pulsed optical heating of the near-surface region of the sample to produce transient thermal emission spectra in the midinfrared spectral region for room temperature samples. The raw data of intensity versus path difference versus time after excitation can be processed in two ways; (1) to yield time-resolved spectra for depth profiling of layered samples; and (2) to yield decay-associated spectra for absolute absorbance measurements of homogeneous samples.