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 = 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.