An Analytical Formula for the Energy of the Bound Long-Range 0−g((1)3Πg) State of Cs2

✍ Scribed by M. Aubert-Frécon; S. Rousseau; G. Hadinger; S. Magnier

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 122 KB
• Volume: 192
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1998.7690

✦ Synopsis

Twenty years ago, Stwalley et al. (1) defined "pure long-range states" as states for which all the bound vibrational levels have both inner and outer turning points in the region of large values of internuclear distances. For such values of R, the potential energy curves can be expressed accurately in terms of Coulombic contributions calculated through the usual multipolar expansion and of the atomic spin-orbit splitting ⌬E SO . For alkali dimers dissociating into ns 2 S 1/2 ϩ np 2 P J , the bound states 0 g Ϫ ((1) 3 ⌸ g ) ( J ϭ 3/ 2) are such pure long-range states now observable from photoassociative spectroscopy of ultracold atoms. Up until now, to the best of our knowledge, observations of the 0 g Ϫ ((1) 3 ⌸ g ) state of Rb 2 (2), Na 2 (3-5), and K 2 (6, 7) have been reported. Their analysis (2-8) has been performed successfully in terms of the longrange multipolar expansion coefficients C n , n ϭ 3, 6, 8 of the two parent states (1) 3 ⌺ g ϩ and (1) 3 ⌸ g and of ⌬E SO . The situation for the 0 g Ϫ ((1) 3 ⌸ g ) state of Cs 2 , for which no experimental data have yet been reported, will be somewhat different due to the facts that the predicted equilibrium distance for this molecule (Ϸ26a 0 ) is significantly smaller than for the other dimers Li 2 , Na 2 , K 2 , and Rb 2 (Ϸ253a 0 , Ϸ71a 0 , Ϸ53a 0 , and Ϸ33a 0 , respectively), and that the estimated limiting value R L for the long-range region is larger (Ϸ23a 0 ) than for the other dimers Li 2 , Na 2 , K 2 , and Rb 2 (Ϸ17a 0 , Ϸ18a 0 , Ϸ21a 0 , and Ϸ22a 0 , respectively). The smallest value of R L for the 0 g Ϫ ((1) 3 ⌸ g ) state is estimated from the modified-LeRoy criteria (9) as R L ϭ 2 ͱ3 ͭͱ 1 3 ͗r 2 ͘ 6s ϩ ͱ 1