EFFECT OF TEMPERATURE-VARIATION ON FT-IR SPECTROMETER STABILITY

The effect of temperature variation on Fourier transform infrared (FT- IR) spectrometer response stability is investigated for wavenumbers fr om 10,000 to 100 cm(-1) with the use of a temperature measurement and data acquisition system on the spectrometer optical bench. Spectromete r response instability is correlated with local temperature variation for two FT-IR spectrometer systems, with the use of various infrared s ource, beamsplitter, and detector combinations. The data obtained show that detector responsivity variation and beamsplitter misalignment as sociated with thermal instability of the spectrometer optical bench ar e responsible for the observed response instability. Response variatio n of up to 4% per degrees C temperature variation is observed. Variati ons of the laboratory environment and spectrometer purge gas supply te mperatures are shown to affect spectrometer thermal stability directly .