15min:

JASON F. FULLER, JAN SZCZEPANSKI AND MARTIN VALA, Department of Chemistry and The Center for Chemical Physics, Gainesville, FL 32611.

The ^12,13C isotopic substitution method applied to IR absorption spectra has been successful in identifying the size and the geometry of many molecular systems, including carbon clusters. Using this method we obtained ¹³C-labeled IR spectra in the > 2200 cm^-1 region for linear carbon clusters isolated in an Ar matrix. By comparison to the calculated isotopomer frequencies at the B3LYP/6-31G* level, the observed bands have been assigned to combination modes of ^12,13C_n clusters. In addition, from these combination band frequencies the few symmetrical mode vibrations in the linear C_n (n < 10) clusters have been deduced.