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General conditions causing partial transformation of optical alignment of excited state angular momenta J into orientation at weak linear polarized broad line excitation of molecules are examined. As is shown, the phenomenon takes place under the effect of an external perturbing factor leading to such magnetic sublevel M splitting ω[sub MM′] when ω[sub MM±1]≠ω[sub -M≠1-M] and ω[sub MM′] is of the order of molecular state relaxation rate. An analytical expression is obtained describing the appearing circularity of fluorescence for arbitrary J values. A numeric example is given for [sup 1]∑ state molecules with J=10 assuming a quadratic Stark effect in a homogeneous external electric field. [ABSTRACT FROM AUTHOR]

The paper analyzes magnetic field induced alignment–orientation conversion (AOC) phenomenon caused by simultaneous effect of quadratic terms in Zeeman energy shift and magnetic predissociation (PD), producing asymmetry either in energy splitting ωMM±1≠ω-M∓1-M or in relaxation of coherence ΓMM±1≠Γ-M∓1-M between coherently excited M, M±1 magnetic sublevels. The AOC is registered via the appearance of circular polarization (C) of fluorescence under linearly polarized excitation. The unified perturbation treatment of a molecule in external magnetic field B is presented, accounting for magnetic and intramolecular perturbations via interaction with bonded or continuum states, considering Hund’s (c)-case coupling and dividing the intramolecular perturbation operator into homogeneous (ΔΩ=0) and heterogeneous (ΔΩ=±1) parts. Explicit expressions up to B2 terms are given for energy shift and PD rate, adapted to 1u state in conditions relevant to the B 3Σ-u complex of Te2 molecule. Numeric simulation revealed that nonlinear magnetic energy shift and heterogeneous magnetic PD produce dispersion type fluorescence circularity signals C(B) of different sign. Fitting of experimental data on B1-u, v(J)=2(96) state of 130Te2 molecule allowed to determine the electronic matrix element of paramagnetic Hamiltonian (Ω=0|Ĥpm|Ω=1)≡G±=2.7, as well as the natural Cvhet=±6 s-1/2 and the magnetic αvhet=∓9×103 s-1/2 T-1 rate constants of heterogeneous PD, supposing that the B1-u state PD takes place through 0-u state continuum. As a result, magnetic AOC represents a sensitive method to investigate molecular structure and intramolecular interaction between both bonded and continuum states. Additionally, it has been shown that the magnetic PD effect leads to strong amplification of nonzero field level crossing signals caused by B2 terms... [ABSTRACT FROM AUTHOR]

In the framework of a unified physical model, employed as a basis Hund’s case ‘‘c,’’ a quantitative description has been worked out for experimental data of term values, g factors, and lifetimes of excited B0+u and A1u states, as well as for relative intensities in B0+u–X0+g, A1u–X1g, and B0+u–X1g transitions. The model includes a minimum number of adjustable fitting parameters: deperturbed molecular constants for both states, intramolecular interaction matrix element (η), two electronic matrix elements of magnetic interactions (Gz,G±), as well as two parallel (Re||B0u+–X0g+, Re||A1u–X1g) and two perpendicular (Re⊥B0u+–X1g, Re⊥A1u–X0g+) electronic transition moments. The B0+u state g factors and the intensity distribution over P, R, Q branches in B0+u–X1g transition was found to be most sensitive to weak heterogeneous (ΔΩ=±1) perturbations, and a simple analytic connection between those characteristics has been proposed. The Ω-doubling constant for A1u state levels was evaluated. By transforming the responsible electronic matrix elements to Hund’s case ‘‘a’’ basis, the A1u state has been found to be basically a 3Σ1 component of the B 3Σ-u state, with a small admixture (<14%) of a 3Π1 component of the A 3Πu state, and a change in term notation from A1u to B1u is proposed. [ABSTRACT FROM AUTHOR]

This paper reports the observation of the molecular fluorescence circularity under irradiation with linear polarized light. The phenomenon arises as a result of partial transformation from alignment of the ensemble of molecular angular momenta into orientation due to quadratic correction to Zeeman effect. Circularity rate up to 0.05 at magnetic field 0.4 T was registered in B 3Σu-(1u-)→X 3Σg-(1g-) fluorescence of 130Te2 molecules at angle π/4 with respect to Ê vector of linear polarized exciting light. Quadratic magnetic energy terms are associated with magnetic field induced ΔJ=±1 e/f mixing between 1u-∼1u+ and 1u-∼0u+ states. Circularity data fitting shows that the electronic part of Landé factor caused by 1u-∼0u+ interaction is equal to G± [bar_over_tilde:_approx._equal_to]gl<0u|Ja±|1u>+(gs-gl) <0u|S±|1u>[bar_over_tilde:_approx._equal_to]2.72. [ABSTRACT FROM AUTHOR]

The b 3Πu–A 1Σu+ interaction in Na2 as manifested by A 1Σu+ state Lande factors was investigated. Landé factors gA were measured from the dispersion shape Hanle signal in fluorescence excited by 647.1 and 676.4 nm Kr+-laser lines. The partial contribution gAb due to weak A∼b interaction was extracted from measured g factors for vA, J levels with vA between 8 and 29. The electronic part of the spin–orbit (SO) interaction matrix element Heso = 5.86± 0.20 cm-1 was determined by deperturbation fitting of gAb values. Possible error sources in A 1Σu+ state g-factor treatment due to imperfection in the physical model employed, inaccuracy of existing set of b 3Πu state molecular constants and nonlinear magnetic field effects were analyzed. [ABSTRACT FROM AUTHOR]

Values and signs of Landè factors (g) have been measured for four rovibronic levels of the A 1Σ+u state of the Na2 molecule. Because of a very small product gτ∼10-12 s, the level crossing signal of a dispersion shape was employed using circular light polarization and mutually orthogonal excitation, observation of laser induced fluorescence, and external magnetic field directions. The effects of the b 3Πu, B 1Πu, and a 3Σ+u states on the g factors of the Na2(A 1Σ+u), as well as their dependence on vibrational and rotational quantum numbers, have been theoretically analyzed. An analytical connection has been found between the constants of Λ doubling (q) and Landè factors of the interacting singlet states. Simple expressions have been found for estimating the effects of distant electronic states on q and the g factors without summing over bounded and integrating over continuum levels of the perturbing state. [ABSTRACT FROM AUTHOR]