Thermal stability evaluation for passive FTIR spectrometry

Fourier-transform infrared spectrometry furnishes a viable method of assessing a variety of airborne pollutants with passive remote monitoring. Ensuring accurate and precise open-air monitoring requires evaluation of FTIR spectrometer radiometric performance. The noise equivalent radiance per root Hertz is a radiometric figure of merit that is independent of integration time, interferometer mirror velocity, and spectral resolution. This study demonstrates the utility of the NER per root Hertz metric by examining FTIR spectrometer performance as a function of internal thermal stability, spectral resolution, and integration time. The effect of internal stability on spectrometer radiometric performance is evaluated as a function of external spectrometer temperature.