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

The results of matrix isolation experiments on carbon atoms and clusters generated by pulsed laser ablation of graphite are presented. ${\mathrm{C}}_{\mathrm{3}}$ and other ${\mathrm{C}}_n$ clusters are observed by their infrared absorptions in Ne, ortho-${\mathrm{D}}_{\mathrm{2}},$ and para-${\mathrm{H}}_{\mathrm{2}}$ matrices. ${\mathrm{CH}}_{\mathrm{4}}$ molecules and ${\mathrm{CH}}_{\mathrm{3}}$ radicals are observed in ${\mathrm{H}}_{\mathrm{2}}$ matrices, as are ${\mathrm{CD}}_{\mathrm{4}}$ molecules in ${\mathrm{D}}_{\mathrm{2}}$ matrices. The ${\mathrm{CH}}_{\mathrm{4}}{\mathrm{:C}}_{\mathrm{3}}$ concentration ratio in the ${\mathrm{H}}_{\mathrm{2}}$ 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 ${\mathrm{C}}_n$ doped cryogenic para-${\mathrm{H}}_{\mathrm{2}}$ samples produced by combined laser ablation and gas condensation in an enclosed cell. Their nonobservation of any hydrocarbon reaction products (particularly ${\mathrm{CH}}_{\mathrm{4}}$ ) is explained by the lower intrinsic absorption strengths of the ${\mathrm{CH}}_{\mathrm{4}}$ vs ${\mathrm{C}}_{\mathrm{3}}$ vibrational transitions, and by attributing a low ${\mathrm{C}}_{\mathrm{1}}{\mathrm{:C}}_{\mathrm{3}}$ production ratio to the ablation process under their laser intensity and wavelength conditions.