The absorption and magnetic circular dichroism spectra of the 2P+-2S transition of matrixisolated copper atoms have been measured in krypton and xenon matrices. A dramatic reversal in the MCD 'if' term pattern is observed. From a spectral band moment analysis it is shown that: (1) noncubic lattice cage vibrational motions are more important than cubic ones in contributing to the observed bandwidths and (2) the Cu excited state spin-orbit coupling constant (A) in krypton is reduced to 57% of its gas phase value, whereas in xenon it is reduced to -14% of its gas phase value. Calculations using the Moran model show that the excited state geometry of the metal/rare gas cage is distorted via the Jahn-Teller effect in opposite ways in krypton and xenon matrices. The negative sign of A in xenon reveals a reversal in the order of the 2 P state spin-orbit multiplets. Neither this reversal nor the reduction of A in krypton can be accounted for by the Jahn-Teller effect. We attribute the spin-orbit constant reduction to the overlap of the Cu 4p orbital with the np of the rare gas matrix cage atoms. The calculated spin-orbit reduction factors (in Ar, Kr, and Xe) agree well with the experimental ones if a contracted Cu 4p orbital is used. In the same way the ground state g factor shift with matrix atom type, observed by Kasai and McLeod, is semiquantitatively accounted for by calculation of the overlaps between the Cu 4s orbital and the np orbitals of the rare gas cage atoms.

The absorption and MCD spectra of the 2 P +-2S transition of Cu atoms isolated in argon matrices have been measured over the temperature range 13--25 K. Spectral band moments (up to third order in MCD) have been determined and parameters of interest extracted from them. The observed triplet bands' separation and MCD C term signs are analyzed assuming a static trigonal site distortion. It is shown that a static site distortion model is incapable of reproducing the experimental results. Simultaneous spin orbit and noncubic lattice vibrational couplings (Jahn-Teller effect) are shown to be active in the Cu excited 2p state. The observed triplet of bands and its MCD C terms are satisfactorily described by an adiabatic model developed by Moran.Comparison of the observed band shape to ones calculated by Cho using Monte Carlo methods show that simultaneous 8pin~rbit and e and t 2 lattice mode interactions are operative. The observed reduction of 25% in the excited state spin~rbit coupling constant is attributed to the overlap of Cu 4p orbitals with the Ar 3p orbitals. A new method for the determination of the temperature of matrix-isolated samples is described. The temperature dependence of the MCD first moment and absorption zeroth moment of a matrix-isolated paramagnetic species is determined once to find the lowest temperature attainable.

Theory of magnetic linear dichroism. Application to matrixisolated atomic transitions J. Chem. Phys. 74, 5411 (1981); 10.1063/1.440944 Measurement of magnetic circular dichroism of matrixisolated high temperature molecules Rev. Sci. Instrum. 51, 905 (1980); Equations useful for the moment analysis of magnetic circular dichroism (MCD) and absorpti~n bands of ~+-S el~c~ronic transitions of atoms or ions/or any spin multiplicity have b~n denved. In partIcular, It IS sh~wn that the first through third MCD moments, together wIth the zeroth and second absorptIon moments may be employed to obtain such electronic and vibronic parameters as (1) the excited state spin-orbit coupling constant, (2) the excited state orbital g factor, and (3) the contributions of the cubic and noncubic metalllattice cage modes to the spectral absorption bandwidths. The MCD and absorption spectra of Cr atoms isolated in krypton and xenon matrices are presented. Forbidden transitions between the two allowed 7p+-7Sbands are observed. Their appearance is ascribed to second-order spin-orbit coupling to the near-lying 7 P states. The moment equations are applied in an appropriate manner to the observed allowed bands. Excited state spin-orbit splitting ( -14 cm-I:Cr/Kr and -56 cm -1 :Cr/Xe) are found to be significantly reduced from the gas phase value ( + 194 em-I) for thez 7 p+-7S transition. For they 7P+-Sband, an enhancement ( + 275 cm-I:Cr/Kr) and a reduction ( + 171 cm-I:Cr/Xe) from the gas phase value of 206 cm-I are observed. It is further shown that the Jahn-Teller effect is strongly operative in the z 7 P +-7 S Cr band in both matrices.

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