Vacuum Ultraviolet Spectroscopy of the Carbon Molecule C3 in Matrix Isolated State: Experiment and Theory

Abstract

Carbon molecules were produced by evaporation of graphite and matrix-isolated in solid neon and argon. Using synchrotron radiation, the absorption spectra of the carbon clusters were recorded from 1100 to 5600 A, and the fluorescence or phosphorescence spectra were recorded from 1200 to 9000 A. We observed an intense, broad absorption band system centered at around 1600 A in neon and 1700 A in argon. By measuring the excitation spectrum of the a 3Πu → X 1Σ+g phosphorescence and checking the intensity correlation with the known 1Πu ← X 1Σ+g absorption band, we could show that the observed VUV band system is the allowed 1Σ+u ← X 1Σ+g electronic transition of the C3 molecule. At the blue and the red side of the band system, distinct progressions can be observed which most likely correspond to a symmetric stretch of about ν1 ≈ 1100 cm-1 and a bending mode of about ν3 ≈ 550 cm-1, respectively. In the band center, however, a complicated superposition of several vibrational progressions appears indicating that b...