Resonance Raman spectroscopy of matrix-isolated mass-selected Fe-3 and Ag-3

Raman spectroscopy of matrix-isolated, mass-selected Fe-3 and Ag-3 reveal t hat both are Jahn-Teller distorted triangular molecules. The observed spect rum of Ag-3 can be accounted for adequately using an approximate Jahn-Telle r potential truncated at the quadratic term [Wedum , J. Chem. Phys. 100, 63 12 (1994)] with parameters omega(a)=119 cm(-1), omega(e)=99 cm(-1), k=1.92, and g=0.29. For Fe-3, the spectrum is more complex, most likely due to the fact that spin-orbit coupling plays an important role in this high-spin cl uster in addition to the quadratic Jahn-Teller terms. The overall pattern o f the spectrum suggests that in Fe-3 the Jahn-Teller distortion is likely s mall, and a peak at 249 cm(-1) is tentatively assigned to its symmetric str etch. (C) 1999 American Institute of Physics. [S0021-9606(99)01638-4].