The photodissociation lifetime of the van der Waals molecule I2He

Abstract

The photodissociation lifetime of the van der Waals molecule I2He has been measured as a function of v, the iodine stretching vibrational quantum number. Lifetimes were deduced from the measured width of the R-branch head of the fluorescence excitation spectrum obtained in a supersonic free jet. The linewidth (HWHM) varied from 0.0120 cm−1 for v′=12 to 0.0700 cm−1 for v′=26, corresponding to lifetimes of 221 psec (v′=12) and 38 psec (v′=26). The inferred lifetimes were compared to calculated lifetimes provided by a recent theory of vibrational predissociation.