The photodissociation cage effect in van der Waals complexes: Fluorescence spectra of I2 <i>B</i>(3Π0+<i>u</i>) from the hindered photodissociation of I2Ar at 488 nm

Abstract

The B→X fluorescence from I2 produced in the hindered photodissociation of I2Ar at 488 nm has been resolved. The spectra show several vibrational progressions with low rotational energy, the most prominent of these is a (v′,0) progression extending from v′ = 49 to at least v′ = 23. The I2Ar complexes were excited and the I2 fluorescence was observed under collision-free conditions in a supersonic free-jet expansion. We attribute these observation to one-atom photodissociation cage effect in the I2Ar comples, in which the molecular iodine, although excited more than 400 cm−1 above B state dissociation limit, is prevented from dissociating by energy transfer to the argon atom, resulting in the breaking of the van der Waals bond: I2Ar→I2(B)+Ar, leaving the iodine molecule in a bound level of the B electronic state, 386–1889 cm−1 below the dissociation limit. (AIP)