A2 Pi Research Articles

The electronic spectrum of magnesium hydride and magnesium deuteride

The absorption spectra of MgH and MgD have been examined under high resolution and several new features observed. In the A2 Pi -x2 Sigma + transition the 0P12 satellite branch has been identified and assigned for both molecules. Measurements on the C2 pi -x2 sigma + system of MgH indicate that the C state is inverted with A= -3.7 cm-1. The MgD absorptions at 236.4 nm and 236.0 nm, previously considered to belong to independent electronic transitions, have been shown to be, respectively, the P and Q heads of the 1-0 band of the C2 Pi -x 2 Sigma + system. Rotational analysis yields the following constants for the C2 Pi state of MgD; Be=3.256 cm-1, De=9.2*10-5 cm-1, beta e=0.25*10-5 cm-1, re=0.1669 nm and Delta G(1/2)=1140.1 cm-1.

Calculation of the photoionization cross section of N2from first threshold at 500 AA

A method of determining photoionization cross sections for homonuclear diatomic molecules is outlined. For the initial electronic states self-consistent field-linear combination of atomic orbitals-molecular orbital wave functions constructed from Slater type atomic orbitals are used. A preliminary calculation is performed using two-centre Coulomb waves for the final electronic states. The quantum-defect approach to finding phase shifts is investigated but uncertainties in the interpretations of Rydberg series of molecular states makes it difficult to obtain reliable continuum functions. Results are given for photoionizing transitions in N2(x1 Sigma g+) which give rise to the states N2+(x2 Sigma g+, A2 Pi u, B2 Sigma u+). The vibrational states are accounted for with Franck-Condon factors.

Isotope shift studies in the A-X system of the BeBr molecule

The A2 pi -x2 Sigma system of the BeBr molecule has been re-investigated under high dispersion (1.25 AA mm-1). The previous analysis has been confirmed by isotopic studies and the vibrational constants are modified.