Absorption line profile measurement of rovibrational transition of acetylene molecule using a fiber comb spectrometer

We have been developing a spectrometer to record an accurate absorption line profile of a rovibrational transition of acetylene in the 1.54 mum region using an extended cavity laser diode (ECLD) and a mode-locked fiber frequency comb. With the spectrometer, we have recorded the absorption line profiles for various pressures and have observed the collisional narrowing effect on the inhomogeneous Gaussian widths. Information of the Gaussian width which reflects the Maxwell-Boltzmann distribution can be used to estimate accurate temperature of the sample gas and also have possibility to provide a way to determine the Boltzmann constant.