Infrared spectroscopy of HOCl embedded in superfluid helium nanodroplets: Probing the dynamical response of the solvent

The rotationally resolved depletion spectrum of hypochlorous acid embedded in helium nanodroplets in the 2.8 mu m region is reported. The narrow a-type lines are asymmetrically skewed in the direction of the band origin, and an analysis of their line shapes based on the chirped damped oscillator function introduced by van Staveren and Apkarian [J. Chem. Phys. 133, 054506 (2010).] yields a response time of the helium solvent of 1 ns. The b-type lines are much broader due to the greater number of droplet states available for relaxation of the excited rotational states. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731283]