Vibrational dynamics of the linear and bent isomers of HF-N2O trapped in 0.4Â K helium nanodroplets

Infrared (IR)-IR double resonance spectroscopy is used to probe the isomerization dynamics of helium solvated HF-N2O following the vibrational excitation of one of two stable isomers on the intermolecular potential energy landscape. An upstream pump laser excites the H-F stretching fundamental of either the linear ONN-HF or the bent NNO-HF isomer, while a downstream probe laser is scanned through the bands of both isomers to test for photo-induced isomerization. Vibrational excitation of the H-F stretch mode leads to the isomerization of a fraction of the upstream population, regardless of the identity of the pumped isomer. The measured isomer interconversion is consistent with vibrational predissociation followed by geminate recombination. A fraction of the upstream population is unaccounted for by the downstream probe. We propose that a fraction of the missing population is due to the mismatch in the timescales of complex recombination and pump, probe events.