Pressure-induced shift and broadening of acetylene lines in the region 6580–6600 cm −1

Highly accurate measurements of pressure shift and broadening parameters of acetylene absorption lines in the region 6580–6600 cm −1 have been performed by tunable diode laser spectroscopy (TDLS). For these purposes the three channel spectrometer with distributed-feedback diode laser, operated at 1.53 μm was used. The laser is generating pulses of 4–10 ms duration at a repetition frequency of 40 Hz. A temperature-stabilization system, using a thermoelectric cooling unit affords a temperature stability of the order of 10 −4 K in the temperature range from −15 to +50 °C. A three channels acquisition system ensured simultaneous real time recording of the sample gas absorption spectrum and of two spectral calibration signals (Fabry–Perot fringes and low-pressure reference lines). We have measured the pressure-induced self-shift and broadening coefficients for six lines of the R-branch in the ν 1 + ν 3 rotation–vibration band of acetylene 12C 2H 2. The self-shift coefficients have been determined for these lines in the wide pressure region. A non-linear behavior of the pressure dependence of the shift was observed. The temperature exponent n of pressure-induced broadening and shift are reported.