To gain further understanding of the C-H bond-breaking process on single atoms, the authors have extended their studies to B atoms and have compared these with Al, Ga, and In atoms. In order to study all of these systems under similar conditions the authors have designed a matrix-isolation unit that utilizes an excimer laser as a heat source for evaporation of bulk B, Al, Ga, and In. The basic matrix unit is similar to what they have described earlier. However, the laser beam (75 mJ/pulse and about 5 pulses/s) is directed through the center of the cold window (a hole in the window) onto the target, which is vaporized, and as the laser beam bores a hole in the target the exiting vapor is directed back along the laser beam path and onto the window. This design allows evaporation of almost any material and the vapor is deposited immediately after each laser pulse (so the sequence is pulse-deposit-pulse-deposit etc., and the light should not perturb the gaseous species traveling to the window). Using this laser evaporation method combined with UV-vis and IR spectroscopy, the authors have monitored the behavior of B, B/sub 2/, Al, Al/sub 2/, Ga, and In atomsmore » and dimers in the presence of argon (Ar) and CH/sub 4/.« less