Dynamical spectroscopy of many-body interactions. Coherent vibrations and predissociation of I2(B) in solid Kr

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Abstract
I-2(B) isolated in Kr matrices is prepared between 560 and 490 nm, and probed via the f(0(g)(+)) <-- B(0(n)(+)) transition, with a time resolution of 150-200 fs. It is shown that the prepared vibrational population evolves coherently and decays in amplitude owing to predissociation. Where the population is prepared on a single electronic surface, near lambda = 550 nm, the experimental signal can be reproduced quantitatively via classical simulations. The analysis yields: (a) the location of the f(0(g)(+)) ion-pair state, the electronic solvation energy of which the Kr is determined as 4300 cm(-1), (b) the characterization of vibrational relaxation dynamics, which near upsilon = 20 reaches a limiting decay rate of 60 cm(-1) per period and (c) a direct measurement of the host-induced electronic predissociation lifetime of 4.5 ps. With the assumption that this is due to B --> a curve crossing, an electronic matrix element of 54 +/- 7 cm(-1) is implied in solid Kr. The solid-state results are discussed in relation to measurements in other phases: gas, liquid and clusters. The example is used as an illustration of dynamical spectroscopy, as time-dependent resonances which can be interpreted through analysis of the underlying many-body dynamics.