Matrix isolation spectroscopy of laser ablated carbon species in Ne, D2, and H2 matrices

Abstract

The results of matrix isolation experiments on carbon atoms and clusters generated by pulsed laser ablation of graphite are presented. C3 and other Cn clusters are observed by their infrared absorptions in Ne, ortho-D2, and para-H2 matrices. CH4 molecules and CH3 radicals are observed in H2 matrices, as are CD4 molecules in D2 matrices. The CH4:C3 concentration ratio in the H2 matrices is seen to increase dramatically with increasing ablation laser intensity. These results confirm and illuminate previous work by Miki, Wakabayashi, Momose, and Shida [J. Phys. Chem. 100, 12135 (1996)] on Cn doped cryogenic para-H2 samples produced by combined laser ablation and gas condensation in an enclosed cell. Their nonobservation of any hydrocarbon reaction products (particularly CH4) is explained by the lower intrinsic absorption strengths of the CH4 vs C3 vibrational transitions, and by attributing a low C1:C3 production ratio to the ablation process under their laser intensity and wavelength conditions.