Nuclear size effects in rotational spectra: a tale with a twist

T. SAUE

Laboratoire de Chimie et Physique Quantiques
Université de Toulouse 3 (Paul Sabatier), 
118 route de Narbonne, 31062 Toulouse (FRANCE)

Abstract

In the early 1980s Tiemann and co-workers reported [1] a series of high-resolution rotation spectroscopy experiments for isovalent, closed-shell diatomics AB, for which their isotope data did not match the known mass-dependent corrections to the extracted spectroscopic constants.  In follow-up publications Tiemann and co-workers therefore introduced additional correction factors due to the finite size of nuclei [2] and built a sound theoretical foundation of the molecular field shift in rotational spectra [33].  In this contirbution we report a 4-component relativistic benchmark study of the isotopic field shift in the rotational spectrum of three diatomic molecules: TlI, PbTe and PtSi.  We re-examine theory and compare with previous experimental and computational studies.  Our conclusions [4] suggests a curious coincidence of errors in both theoretical and experimental approaches.

[1] E. Tiemann, H. Arnst, W.U. Stieda, T. Törring, and J. Hoeft, Chem. Phys., 67 (1982) 133
[2] H. Knöckel and E. Tiemann. Chem. Phys., 68 (1982) 13
[3] J. Schlembach and E. Tiemann, Chem. Phys., 68 (1982) 21
[4] S. Knecht and T. Saue, Chem. Phys. (2011) accepted