Optical singlet and triplet bands of homonuclear alkali diatomics attached to cold helium clusters
- Princeton Univ., NJ (United States)
Large helium clusters consisting of several thousand atoms are produced in a supersonic expansion and doped with alkali atoms in a low pressure pick-up scattering cell. Laser-induced fluorescence spectroscopy is used to probe the influence of the cold He environment (internal temperature of 0.4K) on the formation and spectra of alkali molecules. Here, the authors will report measurements on the homonuclear diatomics Li{sub 2}, Na{sub 2}, and K{sub 2}. As published earlier, weakly bound states can be formed due to the low temperature. The authors have recorded both laser excitation spectra and spectrally resolved emission for the 1{sup 3}{Pi}{sub g} - 1{sup 3}{Sigma}{sub u}{sup +} transition of Li{sub 2} and K{sub 2} as well as for the 1{sup 3}{Sigma}{sub g}{sup +} - 1{sup 3}{Sigma}{sub u}{sup +} transition of Na{sub 2}. The triplet transitions in Li{sub 2} and in K{sub 2} had not been directly observed so far. In the case of Li{sub 2}, the upper state potential is weakly repulsive and, for K{sub 2}, the 1{sup 3}{Pi}{sub g} state has a shallow well with a barrier towards dissociation. After excitation of this state, the spectrally resolved fluorescence reveals the atomic K (4p-4s) transition is the strongest decay channel, while also the K{sub 2} B{sup 1}{Pi}{sub u}-X{sup 1}{Sigma}{sub g}{sup +} and 1{sup 3}{Pi}{sub g}-l{sup 3}{Pi}{sub u}{sup +} emission are observed. Singlet A{sup 1}{Sigma}{sub u}{sup +}-X{sup 1}{Pi}{sub g}{sup +} transitions have been recorded for Na{sub 2} and K{sub 2}. The vibrational bands consist of distinct, narrow zero-phonon lines, a narrow gap, and a wide phonon wing towards the blue. The dynamics of the alkali dimer-He cluster interaction will be discussed.
- OSTI ID:
- 437256
- Report Number(s):
- CONF-9606118-; TRN: 96:005696-0052
- Resource Relation:
- Conference: 51. Ohio State University international symposium on molecular spectroscopy, Columbus, OH (United States), 10-14 Jun 1996; Other Information: PBD: 1996; Related Information: Is Part Of Ohio State University 51st international symposium on molecular spectroscopy; PB: 272 p.
- Country of Publication:
- United States
- Language:
- English
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