Spectra and relaxation of Hg atoms and molecules in low temperature matrices. II. H2O/Ar and NH3/Ar matrices

The absorption, excitation and emission spectra are recorded for Hg⋅NH3 and Hg⋅H2O/D2O complexes and Hg(NH3)n and Hg(H2O)n/(D2O)n clusters in argon and krypton matrices. The excited states correlated to the 3P1 state of Hg were selectively pumped. The 3P1■3P0 nonradiative relaxation of HgM (HgMn) systems is so efficient that the 3P1→1S0 emission is completely quenched. The excited systems decay by the 3P0→1S0 emission, this radiative transition being weakly allowed. As evidenced by the broad band exciplex emission, these systems are strongly bound in their excited states correlated to the 3P0 state of Hg, while the interaction of ground-state Hg atoms with water and ammonia is weak. The existence of specific Hg...(H2O)n sites with the emission spectra involving a coupling between electronic transition in Hg and intramolecular modes of the H2O (D2O) molecule is reported.