New features of an FT spectrometer using LED sources

- Efficiency of LED emitters in high resolution Fourier spectroscopy has been studied.
- Signal-to-noise ratio in the spectra reached 1×105.
- Using LED improves the detection sensitivity by 3 orders of magnitude in UV region.

The efficiency of LED emitters in high resolution Fourier spectroscopy with a small multipass cell has been shown. Such aspects of Fourier spectroscopy as intensity of the light sources, their stability, and spectral range were considered. Using a 2.5 W LED emitter as a light source for the spectrometer with a 60-cm multipass cell during a 24-h measurement time and by optimizing a number of passes in the cell, we have achieved a signal-to-noise ratio of 1×105 which corresponds to a minimal detectable absorption coefficient of 6×10−9 cm−1. This made it possible to determine the parameters of water vapor lines with the intensity of 2×10−28 cm/molecule. The absorption spectra of H2O and CO2 isotopologues in the range of 10,000 to 23,000 cm−1 were recorded using high sensitivity Fourier spectrometer.