Effect of Temperature Variation on FT-IR Spectrometer Stability

Abstract

The effect of temperature variation on Fourier transform infrared (FT-IR) spectrometer response stability is investigated for wavenumbers from 10,000 to 100 cm⁻¹ with the use of a temperature measurement and data acquisition system on the spectrometer optical bench. Spectrometer response instability is correlated with local temperature variation for two FT-IR spectrometer systems, with the use of various infrared source, beamsplitter, and detector combinations. The data obtained show that detector responsivity variation and beamsplitter misalignment associated with thermal instability of the spectrometer optical bench are responsible for the observed response instability. Response variation of up to 4% per °C temperature variation is observed. Variations of the laboratory environment and spectrometer purge gas supply temperatures are shown to affect spectrometer thermal stability directly.