Abstract :
Shifts in the ground-state vibrational fundamental frequencies of diatomic and small polyatomic free radicals, molecular ions, and other short-lived molecules upon trapping in neon and argon matrices are reviewed, with extensive documentation. Recent experimental and theoretical papers concerned with matrix shift phenomena are also discussed. The vibrational fundamentals of most molecules appear at somewhat lower frequencies in an argon matrix than in a neon matrix. Distributions of the matrix shifts have been obtained for stretching, hydrogen-stretching, and bending fundamentals. Neon-matrix shifts are typically smaller than argon-matrix shifts. There is a slight tendency for stretching vibrations observed in an argon matrix to lie below the gas-phase band centers.
