State-to-state studies of intramolecular energy transfer in highly excited HOOH(D): Dependencies on vibrational and rotational excitation
We use infrared-optical double resonance excitation, together with laser induced fluorescence (LIF) product detection, to measure rotationally resolved vibrational overtone spectra of hydrogen peroxide at energies up to 4500 cm(-1) above the O-O dissociation threshold. The spectroscopic constants obtained from such spectra help characterize the potential energy surface and provide a stringent test for any theoretical representation thereof. Line profiles of individual rovibrational features provide information on the vibrational and rotational dependence of the intramolecular dynamics. Coupling to the manifold of optically inactive background states is independent of the total density of rovibrational states but rather controlled by specific low-order coupling terms in the Hamiltonian. Moreover, we find no significant difference in the IVR dynamics between states with all quanta in a single OH oscillator or distributed between the two local OH stretches. Finally, increasing rotation around the O-O pseudo-figure axis clearly enhances the IVR rate in most vibrational bands of H2O2 due to increased a-axis Coriolis coupling. Comparison to other OH stretch containing molecules allows us to define chromophore specific dynamics of this light atom oscillator. (C) 2000 American Institute of Physics. [S0021-9606(00)01517-8].