Cesium dimer spectroscopy on helium droplets

Abstract

Visible absorption spectra of cesium-doped helium nanodroplets between 14,500 and 17,600 cm(-1) were probed by laser-induced fluorescence. A strong absorption band peaking around 16,700 cm(-1) is identified as Cs2 1(a) 3Sigmau+-3 3Sigmag+ transition. A broad unstructured band near 17,520 cm(-1) is assigned as the Cs2 1(X) 1Sigmag+-2 1Sigmau+ transition. Explanations of the observations are discussed on the basis of ab initio potential curves calculated by Spies and Meyer [(unpublished)]. All spectra have been modeled using narrow Frank-Condon windows around the equilibrium internuclear distance of the lowest singlet and triplet states. Many observed absorption peaks of smaller intensities could be identified, some of which may be due to transitions of cesium trimers formed on the droplets.

One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets

“…In the range between 15 000 and 18 500 cm −1 , six molecular transitions of cesium dimers on helium droplets were previously identified. 39 At energies beyond 21 000 cm −1 , however, we do not trust an assignment based on free molecule potentials alone. The increasing state density and shifts due to the helium environment forbid any speculation.…”

Predictions for the observation of KRb spectra under cold conditions

“…Together with the fact that we show only excitations from the lowest vibrational state of 1 1 + and 1 3 + due to the helium temperature of 0.37 K, the predictions can provide an important step for the identification of recorded alkali spectra on helium droplets with regard to relative intensities and widths of the band envelopes. A good example in this respect has been the recent assignments of caesium molecular bands [33].…”

Atomic and molecular defects in solid 4He

“…The lines are blueshifted by a few cm −1 and have a spectral width of about 30 cm −1 . Absorption and emission spectra of molecules (dimers) were extensively studied in experiments with helium nano-droplets [174][175][176][177][178]161,179], where all homonuclear and some heteronuclear alkali dimers were formed and investigated. However, until recently, there have only been very few investigations of metal dimers in bulk condensed helium.…”