Long range vibrational energy transfer from ND and NH(A 3Π) to CO and N2 in solid Ar

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Abstract
Three exothermic, yet near resonant (ΔE=13–126 cm−1) vibrational energy transfer processes from ND (A 3Π) to 12CO and 13CO in solid Ar have been investigated. The transfer quantum yield and the nonexponential time‐resolved donor population both follow Förster (dipole–dipole) kinetics as a function of acceptor concentration. The rates exhibit a strong energy gap (transfer exothermicity) law of the form Kα exp(−ΔE/28 cm−1). Reverse transfer of population from 13CO to ND (A 3Π) is not observed, thus indicating a fast sequential exactly resonant transfer of quanta among CO molecules. CO increases the ND X 3Σ→A 3Π inhomogeneous linewidth; however, the transfer kinetics are independent of excitation wavelength within the inhomogeneous linewidth. Transfer from NH(A 3Π) to 12CO is anomalously fast in view of the large ΔE=728 cm−1. Theory is used to relate the energy transfer rates to the vibrational relaxation rates of the isolated donor and acceptor. The hydride dissipates the exothermicity into lattice phonons more efficiently than the deuteride. Limited data suggest a weak energy gap law for the hydride of the form K α exp(−ΔE/310 cm−1).