UV photolysis of (HBr)(n) clusters with known size distribution

The photodissociation of (HBr)(n) clusters is reported using polarized laser light at 243.1 nm. The cluster size is measured in a deflection experiment with He and Ne atoms. A time-of-flight mass spectrometer with low extraction fields is used to obtain the kinetic energy distributions of the hydrogen atoms. At averaged cluster sizes of (n) over bar = 8.1 two distributions are observed with fast peaks of uncaged fragments and with a sharp peak at zero velocity which shows an isotropic angular distribution and which is attributed to complete caging. (C) 1997 Published by Elsevier Science B.V.