Browsing by Browse by FOR 2008 "020201 Atomic and Molecular Physics"

In this Comment, attention is drawn to deficiencies in a recent determination of the magnitude of the molecular quadrupole moment of BCl₃ by the method of foreign-gas microwave pressure broadening, reported by Gierszal, Galica and Mis-Kuzminska [2003 'Physica Scripta' 67 525].

Improved equipment has been used to record the vapor-phase Rayleigh depolarization ratios and electrooptical Kerr effects of CH₃Br, CH₂Br₂, CHBr₃, and CBr₄ at elevated temperatures. The measurements yield experimental values of the anisotropic polarizabilities and the Kerr hyperpolarizabilities of these molecules. As well, Dougherty and Spackman's HUZ-SV(+sd+sp) basis set has been used to compute SCF and MP2-level polarizabilities, and these are compared with the experimental results.

Observations of electric field-gradient induced birefringence (the Buckingham effect) in gaseous N₂ over a range of temperature (≈293–412 K) and pressure (up to ≈2000 kPa) are reported. Analysis of the data shows that the temperature-independent contribution to the effect is not negligible, and values of the molecular hyperpolarizability, B, and quadrupole moment, ⊖, are derived. In the case of the quadrupole moment, the experimental value [⊖=(−4.97±0.16)×10⁻⁴⁰ Cm²] and a state-of-the-art ab initio value [⊖=(−4.93±0.03)×10⁻⁴⁰ Cm²] due to Halkier, Coriani and Jørgensen [Chem. Phys. Lett. 294 (1998) 292] are in excellent agreement.