ACETYLENE SPECTRA IN THE 5 MICRON REGION

Abstract

Author Institution: Department of Physics, The Pennsylvania State UniversityThe $\Pi_{u}-\Sigma^{+}_{g}$ bands $(2\nu_{4}+\nu_{3})^{1}$ at 1940.002 and $1959.697 cm^{-1}$ and $3\nu^{1}_{5}$ at $2169.166 cm^{-1}$ together with fourteen accompanying “hot” bands of $^{12}C_{2}H_{2}$ were measured using a high-resolution grating spectrometer equipped with an InSb photo-voltaie detector. The “hot” bands are the $\Sigma^{+}-\Pi, \Sigma^{-}-\Pi$ and $\Delta-\Pi$ transitions of $3\nu_{4}+\nu^{1}_{4}, 2\nu_{4}+2\nu_{5}-\nu^{1}_{5}\nu_{4}+3\nu_{5}-\nu^{1}_{4}$ and $4\nu_{5}-\nu^{1}_{5}$; in addition, the R-branches of the $\nu_{2}+\nu^{1}_{5}-\nu^{1}_{4}$ and $\nu_{2}+\nu^{1}_{5}-\nu^{1}_{4}\Pi-\Pi$ bands were also observed. The information obtained on the strongly interacting upper states involved in the transitions analyzed has made it possible to arrive at a reliable set of spectroscopic constants (anharmonic and rotation-vibration coupling constants) for the bending modes of the acetylene molecule