THE $A {^{2}}\Pi - X {^{2}}\Sigma^{+}$ NEAR INFRARED ABSORPTION SPECTRUM OF $HC_{2}$ ISOLATED IN SOLID ARGON

Abstract

A consistently good yield of the $HC_{2}$ free radical has been obtained when an $Ar: C_{2}H_{2}$ mixture is codeposited at 12-14 K with a beam of argon atoms excited in a microwave discharge. Using these conditions and the DA3.002 interferometer operated at $0.2 cm^{-1}$ resolution, the $A {^{2}}\Pi - X {^{2}}\Sigma^{+}$ band system of $HC_{2}{^{1,2}}$ has been observed in absorption between 3800 and $7500 cm^{-1}$. Detailed observations of the carbon-13 and deuterium-substituted species of $HC_{2}$, which have yielded information on the position of the band origin and on the vibrational energy levels of both the ground and the excited electronic state, will be considered.