Observation of methane nuclear spin isomers in gas phase at low temperature

A spectroscopic study of methane spectra in the range around 6764 cm −1 was performed at different temperatures (from 55 to 200 K). The recorded spectra were used to increase the precision of transitions lower states energy determination and to retrieve the self-collisional broadening parameter. Both the newly obtained results and the quality of the experimental data were used to evaluate our system in the perspective of nuclear spin conversion measurements.