PHASE CORRECTION IN PIEZOELECTRIC PHOTOACOUSTIC FOURIER-TRANSFORM INFRARED-SPECTROSCOPY OF MICA

Piezoelectric photoacoustic IR spectra of mica are obtained using a Fo urier transform IR spectrometer and lead zirconate titanate (PZT) as a detector. The spectra exhibit negative intensities and transmission l ike bands, instead of more conventional absorption bands generally obs erved with a gas-microphone cell. Correct spectra of mica/PZT are calc ulated only when the interferogram phase is constrained to the first a nd fourth quadrants, similar to the case in differential spectroscopy where negative intensities occur. (C) 1997 Society of Photo-Optical In strumentation Engineers.