TIME-RESOLVED IMPULSE PHOTOACOUSTIC MEASUREMENTS BY STEP-SCAN FT-IR SPECTROMETRY

An impulse/response approach for measuring photoacoustic spectra is de scribed, Instead of the usual modulation from either a chopper or an i nterferometric phase modulation, a radiation pulse is used to generate the photoacoustic (PA) signal at each step of a step-scan FT-IR spect rometer, The signal from the PA cell is recorded as a time-resolved se quence, The time-dependent photoacoustic signal reveals depth-profilin g information for solid samples. Examples of time-resolved impulse pho toacoustic spectra (TRIPAS) of gas and solid samples are presented.