Arsenic monofluoride (AsF, 3Σ): Dissociation enthalpy, ionization potential, electron affinity, dipole moment, spectroscopic constants, and ideal gas thermodynamic functions from a Hartree-Fock molecular orbital investigation

Abstract

Accurate Hartree-Fock wavefunctions were computed by the matrix expansion method of Roothaan for the ground state (3Σ) of AsF at several internuclear separations. The equilibrium internuclear separation (re) was deduced to be 1.72 Å based on a Dunham analysis. It is concluded that the most probable value for D0o (AsF) is 4.2 ± 0.2 eV. The vertical ionization potential and electron affinity are 9.4 ± 0.2 and and 1.1 eV, respectively. It is believed that the computed electric dipole moment is too large, and an amended value of 1.75 D is recommended, with the negative end of the dipole at the fluorine atom. At re, the quadrupole moment measured from the center of mass is −2.44 × 10−26 esu · cm2; however, the reliability of this result is uncertain. Ideal gas thermodynamic functions have been calculated for the temperature range 0–1000°K, based on the formulas of statistical mechanics. Koopmans' theorem yields 18.1 eV for the second ionization potential. A brief discussion of the bond enthalpies of AsF+, AsF2+, and AsF− is also included. Estimates have been made of the first and second ionization potentials of SbF (8.4 and 16.3 eV) and BiF (7.3 and 16.6 eV).