An impulse/response approach for measuring photoacoustic spectra is described. Instead of the usual modulation from either a chopper or an interferometric phase modulation, a radiation pulse is used to generate the photoacoustic (PA) signal at each step of a step-scan FT-IR spectrometer. The signal from the PA cell is recorded as a time-resolved sequence. The time-dependent photoacoustic signal reveals depth-profiling information for solid samples. Examples of time-resolved impulse photoacoustic spectra (TRIPAS) of gas and solid samples are presented.
