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 singlefrequency
velocity-modulation spectroscopy have been used to identify ve rotational bands
of HfF+. This work discusses the rst 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.