Ar-induced pressure effects in the ν1+3ν3 absorption band in 12C2H2

We have used a Ti:sapphire autoscan laser spectrometer to measure Ar-induced pressure-broadening, narrowing and shift effects for 24 individual vibration–rotation lines in the ν1+3ν3 band of 12C2H2. The acetylene and total pressures ranged between 10 and 20 Torr, and between 30 and 310 Torr, respectively. The Voigt profile accounted for the higher pressure measurements while the soft and hard collision profiles were required to fit the lower pressure measurements. Lineshift parameters that are significantly different from the overall behaviour in the band were observed for the R(17) and P(19) lines and are qualitatively attributed to the influence of an intramolecular Coriolis-type coupling on the interparticle interaction potential. Those results confirm all trends of self-collisional measurements recently reported for this band.