Electronic spectrum of the diacetylene radical cation in solid rare gases

Abstract

The matrix isolation and laser induced fluorescence techniques are applied to the study of the electronic spectrum of C₄H⁺₂ and its deuterated varieties. The ion is produced in solid Ne in several distinct sites by VUV photoionization of the parent diacetylene. The major site shows a vibronically well resolved X²Π_g→A²Π_u fluorescence spectrum. Comparison of the fundamental frequencies with the gas phase values shows in most cases negligible perturbation by the solid medium (<0.05%). Study of the fluorescence excitation spectra provides new information about the upper state vibrational potential function.