Spin-orbit splitting and Jahn-Teller effect in rare gas matrix-isolated Ag and Au atoms: a magnetic circular dichroism study

• Published in: Chemical physics Vol. 166; no. 3; pp. 393 - 409
• Main Authors: Roser, Dennis, Pellow, Robert, Eyring, Marc, Vala, Martin, Lignieres, Jean, Rivoal, Jean Claude
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.10.1992; Elsevier
• Subjects: Atomic and molecular physics; Exact sciences and technology; Molecular properties and interactions with photons; Optical activity and dichroism; magnetooptical and electrooptical spectra; Physics; Silver Atoms; Matrix isolation; Temperature; LS coupling; Theoretical study; Jahn Teller effect; Crystal field; Experimental study; Gold Atoms; Absorption spectrum; Magnetic circular dichroism spectrum
• ISSN: 0301-0104
• DOI: 10.1016/0301-0104(92)80098-G

The magnetic circular dichroism (MCD) and absorption spectra of Ag and Au atoms isolated in Ar, Kr and Xe rare gas matrices have been measured. Moment analyses have been carried out on the 2P← 2S absorption and MCD bands for all six systems. The excited state spin-oribit (SO) coupling constants extracted for Ag are 783 cm −1 (Ar), 638 cm −1 (Kr) and 583 cm −1 (Xe) compared to the gas phase value of 614 cm −1. For Au, the SO constants found are 3354 cm −1 (Ar), 3310 cm −1 (Kr) and 2655 cm −1 (Xe) compared to the gas phase value of 2543 cm −1. These SO values are compared to a recent theory for SO splitting of the 2P state in matrix-isolated alkali and noble metals. Significant second-order SO coupling is found between the 2P 3 2 and 4P 3 2 states of Au in Ar and Kr but not Xe matrices. Quantitative details of the coupling, which is very likely the result of matrix- induced shifts of the Au 2P state, are determined. The reasons for the three observed peaks (two are observed in the gas phase) are studied in detail. It is shown that the distorted site model cannot account for both the absorption and MCD spectral band contours. From the moment analysis, is is further demonstrated that Jahn-Teller-active, nontotally symmetric vibrations of the lattice cage are active, contribute significantly to the bandwiths and are responsible, together with SO coupling, for the three-peaked appearance of the band contour. Computations by O'Brien confirm this conclusion for the Ag/Ar case.