The A(2)Pi -X-2 Sigma(+) (0,0) band system of barium monofluoride (BaF) has been recorded using high-resolution laser-induced fluorescence spectroscopy both field-free and in the presence of static magnetic and electric fields. The field-free spectra for the (BaF)-Ba-135, (BaF)-Ba-137, and (BaF)-Ba-138 isotopologues were modeled to generate an improved set of spectroscopic constants for the A(2)Pi (nu = 0) and X-2 Sigma(+) (nu = 0) states. The observed optical Stark shifts for the (BaF)-Ba-138 isotopologue were analyzed to produce the permanent electric dipole moments of 1.50(2) and 1.31(2) D for the A(2)Pi(1/2)(nu = 0) and A(2)Pi(3/2) (nu = 0) states, respectively. The observed optical Zeeman shifts for the (BaF)-Ba-138 isotopologue were analyzed to produce a set of magnetic g factors for the A(2)Pi(nu = 0) and X-2 Sigma(+)(nu = 0) states.

The detection of changes in volume, e.g., in expansivity or aging measurements, are often translated into mercury column height within a glass capillary. We propose a capacitive technique for measuring the meniscus position using a cylindrical capacitor with mercury as the inner electrode, the capillary material as the dielectric, and a metal coat covering the outside surface of the capillary as the second electrode. The measured capacitance changes linearly with meniscus height, as long as the top mercury level remains within the range of the outer electrode. With the demonstrated noise level of 48 nm for our preliminary setup, meniscus height changes beyond 100 nm can be observed via the capacitance.