An Analysis of Hyperfine Interactions in the Electronic Spectrum of AIF

Abstract

Lines in the b 3Σ+-a 3II and c 3Σ+-a 3II systems of AlF show partially resolved hyperfine structure. This structure has been attributed to magnetic interactions involving the 27Al nucleus for which I = 5/2. About twenty unblended lines from the (0, 0) bands of the two systems have been analysed in detail, using a computer programme to simulate the profiles by calculating the frequencies and intensities of individual hyperfine transitions. For low values of the rotational quantum number, the lines show a simple triplet structure, which reflects the case (bβS) coupling in the 3Σ states. Analysis of these lines gives values for the Fermi contact parameters in the two states involved (bF = 0.049 cm-1 and 0.057 cm-1 in the b 3Σ+ and c 3Σ+ states respectively). As the rotational quantum number increases, the hyperfine patterns become less regular, indicating a departure from case (bβS) coupling in the 3Σ states and from case (aβ) coupling in the 3II state. By reproducing the details of these line-shapes, it has also proved possible to determine values for the electron spin-spin and spin-rotation parameters in the two 3Σ states: b 3Σ+ λ = -0.025(10)cm-1 γ = 0.0000(3)cm-1 c 3Σ+ λ = 0.00(1)cm-1 γ = 0.0015(10)cm-1 The experimental values for the Fermi contact parameter of AlF in the a 3II and b 3Σ+ states are well produced by a simple single configuration molecular orbital calculation but the value for the c 3Σ state is rather larger than expected on this basis.

Electronic transitions of cobalt carbide, CoC, near 750 nm: A good example of case (bβS) hyperfine coupling

“…The line strengths for transitions where one of the states is in case (b ␤S ) coupling have been considered by Féménias et al 39 and Brown et al 37 The more complete treatment is that of Ref. 39, but unfortunately the formulas given there cannot be used directly with our energy matrices, since the derivation uses the ''méthode des Moments Inversés,'' where the choice of phases is not consistent with Sec.…”

Emission Spectroscopy of the Triplet System of the BH Radical

“…The pass). While this improved the signal-to-noise ratio by Hamiltonian and principal matrix elements are given by blocking out the strong BH (36), while explicit matrix elements to high tems, it also blocked any off-diagonal triplet bands. To pro-order in centrifugal distortion are given by Brazier et al vide information on the vibrational frequencies in the a 3 P (37).…”

High-Resolution Study of theX21 →X10+Fine-Structure Transition of BiF

“…[2] - [5] are defined in (17) with the exception of the higher order centrifugal diswhere the terms on the right hand side represent the rotatortion correction to the spin-spin coupling term which has tional kinetic energy, the centrifugal distortion correction, the form the electron spin dipole-dipole coupling, the electron spinrotation interaction, the magnetic nuclear spin hyperfine…”

“…The explicit forms of the operators are given in (16)(17)(18). In a Hund's case (a) basis set, the e where [ , ] / is the anticommutator.…”

“…The rotation matrix operator D ( 1 ) . {1 ( v ) is defined in ( 17 ) . While transitions with The only non-zero matrix element of the nuclear spin-rota-DF Å DJ are the strongest for the highest F values, transition term is diagonal, viz., tions with DF Å DJ { 1 may be stronger for some of the other F values.…”