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The theory of vibrational magnetism in symmetric linear molecule is reviewed and extended taking an isolated CO 2 molecule as example. The order of magnitude of the magnetic-dipole transition momen...

The effect of tri-n-butyl phosphate (TBP) and iso-decanol as phase modifiers on the complexation of Eu3+ with octyl-phenyl N,N-diisobutyl carbamoyl methyl phosphine oxide (CMPO) was studied. On an increase of iso-decanol the extraction efficiency of Eu3+ decreases. The metal–ligand stoichiometry was found to be 1:3. The Eu complex of CMPO–TBP was more symmetric compared to CMPO–iso-decanol. The Eu3+ complex exhibited D3h and C3h symmetry for 30% and 5% iso-decanol, while that for TBP was C6v. The radiative, non-radiative life time, electric and magnetic dipole transition probabilities, branching ratio, quantum efficiency etc. were evaluated. The covalency between Eu3+ and CMPO is as follows: CMPO–TBP < CMPO-5% iso-decanol < CMPO-30% iso-decanol.

The paper is devoted to the memory of Brian Wybourne the pioneer in theory of symmetry and spectra of trivalent rare earths. We evaluate here the influence of site symmetry of the surrounding molecules in glass matrices on europium ion used as a probe. A method by which systematic classification can be performed on descending site symmetry in a large number of solid hosts is based on the ratios of intensities of electric to magnetic dipole transition. Experimental work involves preparation of a number of glass matrices prepared by a sol–gel method, and incorporating trivalent europium. The fluorescence arising from the quintet D state is used to evaluate the site symmetry of the probe europium ion in the prepared matrices, crystals, conventionally prepared glasses, solutions, and complexes incorporated in sol–gel matrices. From the large amount of tabulated data one can see that for totally symmetric sites the factor I(D0–F2)/I(D0–F1) is lower than one, and increases to 10 for systems with very low symmet...

We have studied chiral nonlinear optic (NLO) effect in a bent-core molecular system. Particular attention has been paid to the second-order NLO process involving the magnetic dipole transition process. As one of the examples, second-harmonic generation circular difference (SHG-CD) is observed in two chiral domains in the B4 phase of a mixture of P-8-OPIMB/P-8-OPIMB6*. The signs of SHG-CD are different and the absolute values are the same in the two domains.

The microscopic theory of second-order magneto-electric susceptibility in optical region is presented for the case of optical transition 4 A 2 ( 4 T 1 ) → 4 E( 4 T 1 ) in the boracite Co 3 B 7 O 13 I. Both the splitting of Kramers doublets of the ground and excited states and the magnetic field dependence of electric and magnetic dipole transition matrix elements contribute to this susceptibility. The experimental data on dispersion, temperature dependence and absolute value of non-reciprocal birefringence in Co 3 B 7 O 13 I can be adequately described in considered model.

Expressions for the vibrational optical activity of an independent anharmonic oscillator using the second-order contact transformation theory are presented. The relative importance of anharmonicity for the magnetic dipole and electric dipole transition moments is made transparent using the potential constants for Morse oscillator. At this level of theory, the anharmonic contributions appear to be relatively more significant for the magnetic dipole transition moments.

Magnetic dipole transitions of 14 N 16 O ( 2 Π 3/2 - 2 Π 1/2 ) in the far infrared region were observed at high resolution using a Fourier transform spectrometer. The analysis of the data allows us to determine simultaneously the spin-orbit constant A, its centrifugal correction A D and the spin-rotation constant γ for the ground state: A=123.1540(15)cm -1 , A D =-0.000236(43)cm -1 and γ=-0.0148(15)cm -1

Spin-perturbed wavefunctions have been evaluated for the three lowest electronic states of Se2 using the spin-orbit coupling Hamiltonian with MRD-Cl wavefunctions as the zeroth-order basis, and the radiative lifetimes of the a1Δg and b1Σg + states have been determined. Comparison is made with corresponding data for the two lighter group VIB homonuclear diatomics, O2 and S2. The radiative lifetime of the a1Δg state is found to be largely determined by the orbital angular momentum term in the magnetic dipole operator. In the case of the b1Σg + state, the spin contribution to the magnetic dipole moment transition matrix element with X3Σ- g±1 is the most dominant term. The transition probabilities for both the b1Σg + - X3Σ- g and a1Δg - X3Σ- g transitions are found to be significantly larger in Se2 than for either O2 or S2.

A perturber that lies on a reflection plane of a chromophore gives no net helical character to transitions of that chromophore, and hence no circular dichroism spectrum. If, however, a molecule has two such substituents then it may in fact be chiral, with its circular dichroism resulting from the concerted coupling of both substituents to the transition of interest. In this paper the circular dichroism spectra of olefin and carbonyl molecules of this kind are analysed and related to the molecular geometry using an extended independent systems perturbation approach.

The metastable garnet lattice of Gd3Al5O12 is stabilized by doping with smaller Lu3+, which then allows an effective incorporation of larger Eu3+ activators. The [(Gd1-x Lu x )1-y Eu y ]3Al5O12 (x = 0.1-0.5, y = 0.01-0.09) garnet solid solutions, calcined from their precursors synthesized via carbonate coprecipitation, exhibit strong luminescence at 591 nm (the 5D0 → 7F1 magnetic dipole transition of Eu3+) upon UV excitation into the charge transfer band (CTB) at ∼239 nm, with CIE chromaticity coordinates of x = 0.620 and y = 0.380 (orange-red). The quenching concentration of Eu3+ was estimated at ∼5 at.% (y = 0.05), and the quenching was attributed to exchange interactions. Partial replacement of Gd3+ with Lu3+ up to 50 at.% (x = 0.5) while keeping Eu3+ at the optimal content of 5 at.% does not significantly alter the peak positions of the CTB and 5D0 → 7F1 emission bands but slightly weakens both bands owing to the higher electronegativity of Lu3+. The effects of processing temperature (1000-1500 °C) and Lu/Eu contents on the intensity, quantum efficiency, lifetime and asymmetry factor of luminescence were thoroughly investigated. The [(Gd0.7Lu0.3)0.95Eu0.05]3Al5O12 phosphor processed at 1500 °C exhibits a high internal quantum efficiency of ∼83.2% under 239 nm excitation, which, in combination with the high theoretical density, favors its use as a new type of photoluminescent and scintillation material.

We show that, within a simple version of the bond polarizability model based on the approximation of axially-symmetric bonds, the polarized Raman optical activity is simply double the depolarized in a given band. Many of the bands in preliminary polarized and depolarized Raman optical activity spectra obtained with a new optical multichannel instrument accord with this result, which indicates that this and related models provide a useful starting point for interpreting ROA spectra in terms of structural detail. Additionally, our spectra imply that isotropic contributions can usually be neglected in most Raman optical activity bands, but that electric quadrupole contributions, while smaller than magnetic dipole contributions, are still usually significant.

A multipolar semi-classical hamiltonian for magneto-optical intensities is derived by a canonical transformation taking Feynman's formulation of the conventional Pauli hamiltonian as the point of departure. Only interactions up to the order of electric quadrupole and magnetic dipole terms are retained. The resulting hamiltonians are divided into their respective time-independent, single photon and double photon parts, and the difference in the appearance of magnetic field dependent contributions in the perturbation terms is analysed. On the basis of this analysis it is argued that the magnetic field dependent term in the magnetic dipole transition moment operator may lead to a unique single photon process with an amplitude proportional to the static magnetic field. This process leads, amongst others, to transitions between totally symmetric atomic states, in contrast to the standard multipolar selection rules of ordinary spectroscopy.

The b 0+-X 1 0+ and b 0+-X 2 1 sub-systems of SeS have been recorded in emission in the near infrared with high resolution using a Bomem interferometer. The emission was excited by reacting ground state SeS molecules with metastable O2(1Δ g ) molecules. Rotational analyses have been carried out for the 0–0 bands of 80Se 32S, 78Se 32S, 82Se 32S, 76Se 32S and 77Se 32S and for the 1–0, 0–1, 1–2 and 0–2 bands of the more abundant isotopic species. Accurate molecular constants have been derived for the b 0+, X 1 0+ and X 2 1 states. The 0–0 band of 80Se 32S is of particular interest since 4 electric dipole and 3 magnetic dipole branches have been found. By fitting the line intensities to the line strength formulae of Watson, values have been found for the ratio of the parallel to perpendicular electric dipole transition moments as well as for the ratios of these quantities to the magnetic dipole transition moment.

The influence of vibronic coupling on the distribution of magnetic dipole intensity within the crystal field (f-f) spectra of lanthanide (III) complexes is examined. A formal theoretical model is developed which involves vibronically induced mixing among the f electron states of a centrosymmetric lanthanide(III) complex. Expressions are derived for calculating the magnetic dipole intensities associated with the one-phonon (gerade) vibronic lines in the f-f spectra of such a system, and order of magnitude calculations are presented for the octahedral (Oh ) TbCl6 3- complex in Cs2NaTbCl6. The calculated results indicate that the phonon-assisted magnetic dipole lines will have intensities two or three orders of magnitude less than the intensities associated with the pure (zero-phonon) magnetic dipole lines and the phonon-assisted electric dipole lines. However, the vibronically induced magnetic dipole transition moments are predicted to be sufficiently big to be of some importance in determining the chiropti...