Journal of Chemical Physics, Vol.110, No.18, 8992-8999, 1999
Green bands of the CsHg molecule
We report the first observation of laser-induced fluorescence of the CsHg molecule. Cs/Hg vapor mixtures contained in a heat-pipe oven were excited by several different argon ion laser lines. Following these excitations, we observed three distinct peaks at lambda = 492.8, lambda = 498.3, and lambda = 521.5 nm in addition to the well-known fluorescence of the Cs-2 molecule. Based on an analysis using ab initio potential energy curves of Cs-2 and CsHg, we identified the origin of these three distinct peaks as bound-free transitions of CsHg (lambda = 492.8: IV3/2 --> X-1/2, lambda = 498.3: VII1/2 --> X-1/2, and lambda = 521.5 nm: VI1/2 --> X-1/2). Furthermore, we could show that two different production channels are responsible for the formation of the CsHg molecules in the excited states. The excitation of the Cs/Hg vapor mixtures with wavelengths lambda(exc) = 476-514 nm of the argon ion laser results in the production of the CsHg molecules via a photoassociation process, whereas the CsHg molecules are produced in a three-body collision following an excitation with lambda(exc) = 457 nm. These results are confirmed by subsequent quantum-mechanical simulations of the observed laser-induced fluorescence spectra of CsHg.