Magneto-optical properties of defect centres in alkali halide crystals

1967 ◽  
Vol 300 (1460) ◽  
pp. 78-93 ◽  
Keyword(s):  
Optical Absorption ◽  
Silver Atom ◽  
Alkali Halides ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Absorption Bands ◽  
Optical Effects ◽  
Alkali Halide Crystals ◽  
Defect Centres

Zeeman spectroscopy is not practicable for the investigation of the structure of electronic conventional states which give rise to broad optical absorption bands in solids. We have investigated the application of Faraday rotation and circular dichroism techniques to absorption bands of neutral silver atoms and F centres in alkali halides. These centres give rise to optical absorption bands due to transitions of the type 2 S → 2 P which are 2000 to 6000 cm -1 in width because, in part, of strong coupling to lattice phonons. A discussion is given of information which may be obtained concerning the electonic states involved in the 2 S → 2 P transition by analysis of the magneto-optical effects by the method of moments. It is shown, for example, that the spin-orbit coupling constant of the 2 P state of the silver atom is reduced from 613 cm -1 in the free state to 365 cm -1 in KCl, to 102 cm -1 in KBr and to an unmeasurably small value in KI. This cancellation of spin-orbit interaction of the silver atom is assigned to symmetry allowed admixtures of lattice ion wavefunctions into the 2 P state.

Ground configuration splitting in UCl5

1977 ◽  
Vol 55 (10) ◽  
pp. 937-942 ◽  
Author(s):  
A. F. Leung ◽  
Ying-Ming Poon
Keyword(s):  
Crystal Field ◽  
Energy Levels ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Point Charge Model ◽  
X Ray Crystallography ◽  
Charge Model ◽  
Crystal Field Parameters

The absorption spectra of UCl5 single crystal were observed in the region between 0.6 and 2.4 μm at room, 77, and 4.2 K temperatures. Five pure electronic transitions were assigned at 11 665, 9772, 8950, 6643, and 4300 cm−1. The energy levels associated with these transitions were identified as the splittings of the 5f1 ground configuration under the influence of the spin–orbit coupling and a crystal field of C2v symmetry. The number of crystal field parameters was reduced by assuming the point-charge model where the positions of the ions were determined by X-ray crystallography. Then, the crystal field parameters and the spin–orbit coupling constant were calculated to be [Formula: see text],[Formula: see text], [Formula: see text], and ξ = 1760 cm−1. The vibronic analysis showed that the 90, 200, and 320 cm−1 modes were similar to the T2u(v6), T1u(v4), and T1u(v3) of an UCl6− octahedron, respectively.

Magnetic Susceptibilities of 2T2 Ions. Part 1

1972 ◽  
Vol 50 (10) ◽  
pp. 1468-1471 ◽  
Author(s):  
Alan D. Westland
Keyword(s):  
Magnetic Susceptibility ◽  
Excited State ◽  
Reduction Factor ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Magnetic Susceptibilities

An expression for the magnetic susceptibility of octahedral d1 complexes is derived exactly in terms of an orbital reduction factor k taking into account the presence of the formal 2E excited state. Sample calculations show that the improved expression gives results for susceptibility which are lower at times by several percent from those given by previous expressions. The results given by Figgis using Kotani's method are adequately precise when the spin–orbit coupling constant is no larger than ~0.1 Dq.

Theory of spin-orbit coupling in atoms, II. Comparison of theory with experiment

1963 ◽  
Vol 271 (1347) ◽  
pp. 565-578 ◽  
Keyword(s):  
Wave Functions ◽  
Coupling Constants ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Outer Electron ◽  
Coupling Constant ◽  
Radial Wave ◽  
Order Of Magnitude ◽  
Experimental Values

Results of calculations of the spin-orbit coupling constant for 2 p , 3 p , 4 p , and 3 d shell ions and atoms are presented. The calculations are based on a theory developed in a previous paper. Excellent agreement of this theory with experiment is obtained for the 2 p and 3 d shell ions, while calculations using the familiar < ∂ V / r ∂ r > expression for the coupling constant lie 10 to 20 % too high. The exchange terms discussed in the earlier paper make a contribution to the coupling constant of the same sign and order of magnitude as the ordinary shielding terms. For the 3 p and 4 p shell atoms, the calculated coupling constants based on the exact theory and on the < ∂ V / r ∂ r > expression both tend to lie below the experimental values. An explanation for this disagreement is suggested, based on the noded nature of the outer-electron radial wave functions for these atoms. The importance of the residual-spin-other-orbit interaction is discussed, and it is shown that ignoring the form of this interaction may lead to a large variation in the coupling constant within a configuration.

Theory of spin-orbit coupling in atoms I. Derivation of the spin-orbit coupling constant

1962 ◽  
Vol 270 (1340) ◽  
pp. 127-143 ◽  
Keyword(s):  
Exact Expression ◽  
Orbit Coupling ◽  
Tensor Operator ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Matrix Elements ◽  
Coupling Constant ◽  
Hartree Fock ◽  
Operator Form ◽  
Hartree Potential

An exact expression for the spin-orbit coupling constant is derived within the Hartree-Fock description of the atom by considering the two body mutual spin-orbit interaction between electrons. The interaction is rewritten in tensor operator form and the contribution of outer electron-core interactions to the coupling constant is calculated. We find that the usual expression < 3F/r8r > where V is the Hartree potential is only approximate, and that certain exchange type terms, which arise because we are dealing with a two-body interaction and determinantal wave function, must also be included. These exchange terms are not simply related to the ordinary electrostatic exchange. The resulting expression for the spin-orbit coupling constant is given in terms of radial integrals which can be calculated using Hartree or Hartree—Fock wave functions. We also discuss the effective magnetic Hamiltonian to be used for the calculation of matrix elements within an atomic configuration.

On the Phosphorescence of Benzologues of Furan , Thiophene , Selenophene , and Tellurophene . A Systematic Study of the Intra -annular Internal Heavy-atom Effect

1989 ◽  
Vol 44 (3) ◽  
pp. 205-209 ◽  
Author(s):  
M. Zander ◽  
G. Kirsch
Keyword(s):  
Systematic Study ◽  
Linear Correlation ◽  
Heavy Atom ◽  
Vibrational Structure ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Atom Effect ◽  
Internal Perturbation ◽  
Phosphorescence Spectra

Phosphorescence in ethanol and n-pentane at 77 K of the benzologues 1-8 of furan, thiophene, selenophene and tellurophene has been investigated. The rate constants of both the radiative (kPT) and non-radiative (kGT) deactivation of the lowest triplet state correlate linearly with where ck denotes the Hückel AO coefficients in the HOMO of the carbon atoms bound to the hetero-atom and ζ is the spin-orbit coupling constant of the hetero-atom present. - The linear correlation observed between kPT and kGT is an example for the Orlandi-Siebrand rule. - The influence of an external heavy-atom perturber (methyl iodide) on phosphorescence lifetimes and the vibrational structure of phosphorescence spectra is the more efficient the less efficient is the internal perturbation caused by the intra-annular heavy-atom.

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