Photoassociation of cold calcium atoms through the A {sup 1}{sigma}{sub u}{sup +}(1 {sup 1}D+1 {sup 1}S), c {sup 3}{pi}{sub u}(1 {sup 3}P+1 {sup 1}S), and a {sup 3}{sigma}{sub u}{sup +}(1 {sup 3}P+1{sup 1}S) states: An ab initio nonadiabatic treatment
- Laboratoire PALMS, UMR 6627 du CNRS, Universite de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France)
A nonadiabatic theory of photoassociation spectra and spontaneous emission processes in diatomic molecules is presented. This theory was applied in nearly exact nonadiabatic calculations of the photoassociation intensities to the A {sup 1}{sigma}{sub u}{sup +}(1 {sup 1}S+1 {sup 1}D), c {sup 3}{pi}{sub u}(1 {sup 3}P+1 {sup 1}S), and a {sup 3}{sigma}{sub u}{sup +}(1 {sup 3}P+1 {sup 1}S) manifold of states for two colliding calcium atoms at ultralow temperatures and of the spontaneous emission coefficients to the ground X {sup 1}{sigma}{sub g}{sup +} electronic state. The calculations were based on most recent state-of-the-art ab initio results for the potential energy curves for the ground X {sup 1}{sigma}{sub g}{sup +} and excited A {sup 1}{sigma}{sub u}{sup +}(1 {sup 1}S+1 {sup 1}D), c {sup 3}{pi}{sub u}(1 {sup 3}P+1 {sup 1}S), and a {sup 3}{sigma}{sub u}{sup +}(1 {sup 3}P+1 {sup 1}S) states, for the spin-orbit and nonadiabatic coupling matrix elements, and for the transition dipole moment governing the A {sup 1}{sigma}{sub u}{sup +}<-X {sup 1}{sigma}{sub g}{sup +} transitions. The computed photoassociation spectrum shows several transitions in the detuning frequency range up to -3000 GHz. This frequency range corresponds to vibrational levels of the J{sup '}=1 state of Ca{sub 2} that can mostly be assigned to the c {sup 3}{pi}{sub u} state. The two by far most intense lines at a detuning frequency around -800 GHz correspond to the last two bound rovibrational levels lying below the 1 {sup 3}P+1 {sup 1}S asymptote which are heavily mixed and can partly be assigned to the A {sup 1}{sigma}{sub u}{sup +} state. The corresponding lifetimes and Franck-Condon factors suggest that these levels can be detected experimentally and should show a relatively efficient spontaneous emission to the ground state. An analysis of the branching ratios describing the probability of the decay from these two levels to bound vibrational levels of the ground electronic state shows that the decay will end in the levels with the vibrational quantum number between 10 and 16 with a total probability well over 90%.
- OSTI ID:
- 20718360
- Journal Information:
- Physical Review. A, Vol. 72, Issue 1; Other Information: DOI: 10.1103/PhysRevA.72.012702; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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