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

Sinclair, Laura Cathleen

Graduate Thesis Or Dissertation

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

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/mc87pq31z

Abstract

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)^-1/2with 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.

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