BaF Molecule Research Articles

Enhancement of the electric dipole moment of the electron in the YbF molecule.

We report results of ab initio calculation of the spin-rotational Hamiltonian parameters including P- and P,T-odd terms for the BaF molecule. The ground-state wave function of BaF molecule is found with the help of the relativistic effective core potential method followed by the restoration of molecular four-component spinors in the core region of barium in the framework of a nonvariational procedure. Core polarization effects are included with the help of the atomic many-body perturbation theory for the Barium atom. For the hyperfine constants the accuracy of this method is about 5-10 %. [S1050-2947(97)50311-8].

Lifetime measurements of excited molecular states using a Ti:sapphire laser

A time resolved experiment on the lowest lying states of barium fluoride has been performed by applying laser resonance methods in the near infrared and green-blue wavelength regions. The A2Π and B2Σ+ states have been examined using Ti:sapphire laser excitations in the 710–850 nm wavelength region. The C2Π state was examined using the 496·5 nm Ar+ laser line and the lifetime of this state was in accordance with earlier measurements. The lifetimes obtained for the BaF molecule were: A2Π3/2, 46·1 ± 0·9 ns; B2Σ+, 41·7 ± 0·3 ns.

Studies of the electronic states of the BaF molecule

Laser-excited fluorescence and thermal emission spectra, recorded at high resolution by Fourier-transform spectrometry, have been analysed to yield new information about the ground-state, X2Σ+, and six of the lowest-lying electronic states of BaF. In the present paper we give values of the effective constants for X2Σ+, A′2Δ, A 2Π, B 2Σ+, C 2Π, D 2Σ+ and F 2Π derived from an overall simultaneous fit to some 6470 lines assigned to rotational structure of 24 bands of 10 systems. Existing analyses are confirmed and extended, and a rotational analysis of levels of the state C 2Π is given for the first time: the spin-orbit coupling constant in this state is found to increase unexpectedly rapidly with increasing v. The states A′2Δ, A 2Π and B 2Σ+ interact strongly, and their mutual deperturbation, and the determination of their interaction constants form the subject of the following paper (Part II).

Potential energy curves and dissociation energy of group IIA diatomic fluorides

Reliable (RKRV) potential energy curves have been constructed for different experimentally observed electronic states of BeF, MgF, CaF, SrF and BaF molecules from the latest spectroscopic data using the method of Rao and Venkateswarlu. Using a three-parameters Lippincott potential function the precise values of ground state dissociation energies of these molecules have been obtained. Values so obtained are found to be in close agreement with the experimental results.

Hyperfine Interaction and Chemical Bonding in MgF, CaF, SrF, and BaF molecules

ESR spectra of MgF, CaF, SrF, and BaF molecules in their ground Σ2 states were measured while trapped in solid neon and argon matrices at 4°K. g tensors and hyperfine structure (hfs) constants for interaction with 19F, and in the case of SrF and BaF, with 87Sr and 137Ba, were determined. In all cases less than 4% of the spin density is on the F atom, supporting the evidence for their extreme ionicity. The variation in the anisotropic character of the 19F hfs probably indicates a slight increase in covalency in the lighter molecules. The hf interaction with the metal nucleus is quite anisotropic, demonstrating that the unpaired s electron on the M+ ion actually has appreciable p and d character, i.e., that the spherical s electron orbit in the free M+ ion is highly distorted by the F− ion in the molecule. This was supported by an approximate variational calculation considering the F− ion as a point charge. A negative Δg⊥ for the MgF molecule indicates that the lowest-lying Π2 state is regular, in support of Walker and Richards' reinterpretation of the λ-type doubling.