SPECTROSCOPIC CHARATERIZATION OF ThF AND THE LOW-LYING STATES OF ThF$^+$

Abstract

Theoretical calculations predict that internal electric fields as high as 90 GV/cm can be attained by polarizing the $^3\Delta_1$ state of ThF$^+$, 010502/1 (2008). \textit{"Prospects for an electron electric-dipole moment search in metastable ThO and ThF+"}} Consequently, this ion is of interest for investigation of the dipole moment of the electron. However, spectroscopic data have not been reported previously for ThF or ThF$^+$. We have used laser induced fluorescence and resonantly enhanced two-photon ionization to examine ThF. Multiple electronic transitions were observed in the 19530-21300 \wn range. Rotationally resolved data have been obtained, and the ground state is shown to be X$^2\Delta$$_3_/_2$. Pulsed field ionization - zero electron kinetic energy spectra have been recorded for the ThF+ cation. Vibronic progressions of the X$^1\Sigma^+$ and excited $^3\Delta$ states have been identified. The term energy for the $^3\Delta_1$ state was found to be T$_0$=330 \wn. Details of the experiments and spectroscopic constants for ThF and ThF$^+$ will be reported.