William J. Childs

Precise determination of the v and N dependence of the spin-rotation and hyperfine interactions in the CaF X2Σ12 ground state☆☆☆

Abstract The molecular-beam, laser-rf, double-resonance technique has been used to make high-precision measurements of both the v and N dependences of the spin-rotational and hyperfine splittings in the X 2 Σ 1 2 ground state of CaF. The precision (1 ppm) and scope (1 ≤ N ″ ≤ 119, 0 ≤ v ″ ≤ 4) of the data allow evaluation of many of the parameters (with the Dunham expansion) in the Hamiltonian. The results are compared with new ab initio calculations.

Hyperfine and spin–rotational structure of CaBr X 2Σ (v = 0) by molecular‐beam laser‐rf double resonance

The molecular‐beam, laser–rf, double‐resonance technique has been used to make high‐precision measurements of the spin–rotation and hyperfine interactions in the X 2Σ (v = 0) electronic ground state of Ca79Br and Ca81Br. The spin–rotation interaction is found to have a strong N dependence. The Frosch–Foley magnetic hyperfine parameters b and c and the electric–quadrupole hfs parameter eqQ are determined for both molecules.

Crossed-second-order effects in the isotope shift of the ground configuration 4f126s2 of Er I

High-resolution laser-atomic-beam spectroscopy has been applied to study crossed-second-order effects in the isotope shift of the terms 4f126s2 3H and 3F of Er I. A parametric analysis of the cross second-order effects in the isotope shift 170-166Er has been performed. The J dependence of the isotope shift is interpreted through one parameter z4f with a coefficient having the same angular dependence as the spin-orbit interaction. Additional parameters T(SL) with angular coefficients equal to the square of the corresponding expansion coefficients of the wavefunctions are introduced to take account of term-dependent effects.

Hyperfine structure of low-lying even levels of161, 163Dy and167Er by atomic-beam laser-rf double resonance (Short note)

Radiofrequency measurements of the zero-field hyperfine intervals in low levels of167Er and161,163Dy have been made as part of a systematic study of the second half of the 4fN6s2 configuration of the neutral rare-earth atoms. Almost no precise hfs data exist for this region, and a preliminary analysis indicates systematic differences between ab initio theory and experiment.

Hyperfine structure of the A 2 Π state of Ca 35 Cl

The hyperfine structure (hfs) of the A2Π excited state of Ca35Cl has been investigated by using the new rf-pumped, laser-rf double-resonance technique. The optically unresolved hfs components of the R2 (N″ = 101), A ↔ X (0,0) line were resolved by double resonance, and the measured splittings, when combined with the known X2∑+- state hfs spacings, show that the A2Π-state hfs splittings are not more than 1 MHz.