An effective Golden Rule rate expression is derived for the intramolecular vibrational decay dynamics of an initially prepared nonstationary state in an isolated polyatomic molecule. It is shown that the decay rate of the initial state depends on the properties of those states which are directly coupled to the initial state. In many cases, there may be a suppression of the exponential decay rate. An explanation for the insensitivity of some experimental C–H overtone linewidths with increasing excitation energy is also proposed.
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This formula has the form of a simple Golden Rule expression, but care must be taken in calculating the averaged squared coupling in Eq. (8) in order to obtain accurate results [cf. Eqs. (15)‐(20)]. As shown in Sec. IV, the correct average is not a simple arithmetic average and requires some knowledge of the wave function properties of the receptor states.
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© 1988 American Institute of Physics.
1988
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