Development of Frequency Comb Velocity-Modulation Spectroscopy, Spectroscopy of HfF+ and the JILA eEDM Experiment

Broad bandwidth, precision spectroscopy of the molecular ions of interest to the JILA electron electric dipole moment experiment, HfF+ and ThF+, is necessary due to the limited amount of spectroscopic information available and the large theoretical uncertainties in the energy level structure (thousands of wavenumbers). This thesis covers the development of a novel spectroscopic technique, frequency comb velocity-modulation spectroscopy, that provides high resolution, broad spectral bandwidth, ion discrimination and high sensitivity simultaneously. Frequency comb velocity-modulation spectroscopy as well as single frequency velocity-modulation spectroscopy have been used to identify five rotational bands of HfF+. This work discusses the first spectroscopic information for HfF+ which came from our measurement of the 1Π1 – 1Σ+ (0,0) band recorded with single-frequency velocity modulation spectroscopy with a sensitivity of 3x10-7 Hz-1/2. The development of frequency comb velocity-modulation spectroscopy allowed us to cover a thousand wavenumbers of spectral bandwidth and to identify an additional four HfF+ bands. The achieved sensitivity for frequency-comb velocity-modulation spectroscopy was 4x10-8 Hz-1/2 (spectral element)-1/2 with 1500 simultaneous detection channels spanning 150 cm-1 of bandwidth. For a 30 minute acquisition time using 30 interleaved images to densely sample the whole spectrum, this corresponded to a 3x10-7 single-pass fractional absorption sensitivity for each of the 45,000 measurement channels. The spectroscopic information from all five HfF+ rotational bands is presented and molecular constants for the 1Σ+, 3Π1, and 1Π1 states were extracted