Long-Range Interactions and the Oscillator Strength for the ^{ 1 }1_{ u },^{ 1 }0^{ + } _{ u } <-- X^{ 1 }0^{ + } _{ g } Transitions in Zn_{ 2 } |

M.K. Kubkowska, T.M. Szczęśniak and T. Grycuk Institute of Experimental Physics, Warsaw University Hoża 69, 00-681 Warsaw, Poland |

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Received: February 17, 2004 |

The interaction potentials for Zn_{ 2 } electronic states ^{ 1 }1_{ u } and ^{ 1 }0_{ u } ^{ + } correlated with (4^{ 1 }P1+4^{ 1 }S0) asymptote in the long-range region (10--25)A and the oscillator strength f for the absorption transition to these states are derived experimentally from a careful analysis of the self-broadened resonance 213.8nm line of Zn. It is found that although the interatomic interactions at so long distances are dominated by resonance potential of the form C_{ 3 }/R^{ 3 } resulting in the Lorentzian line shape, the parameter C_{ 3 } and thus f value significantly decrease with R decreasing. This effect proved to be a linear function of R^{ -1 } yielding the oscillator strength for the considered line f_{ 0 }=1.456±0.010 from R-->&infty; extrapolation. This value seems to be the most accurate experimental result as yet and shows that the best theoretical values for this quantity are overestimated. It is suggested that the long-range behaviour of the potential energy curves observed here for the first time represents the effective potentials including dominating resonance interactions and a possible slight contribution of the dispersion interactions as well as the R-dependent spin--orbit interaction. |

DOI: 10.12693/APhysPolA.105.317 PACS numbers: 32.70.--n, 32.70.Cs, 32.70.Jz, 33.70.--w, 34.20.--b |