Precision spectra of A 2Σ+,v′=0 ← X 2Π3/2,v"=0,J"=3/2 transitions in 16OH and 16OD

Meek, Samuel

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https://hdl.handle.net/2142/100587 Copy

Description

Title

Precision spectra of A 2Σ+,v′=0 ← X 2Π3/2,v"=0,J"=3/2 transitions in 16OH and 16OD

Author(s)

Meek, Samuel

Contributor(s)

• Furneaux, John
• Fast, Arthur

Issue Date

2018-06-18

Keyword(s)

Mini-symposium: Frequency-Comb Spectroscopy

Abstract

The hydroxyl radical, OH, is a prototypical open-shell diatomic molecule that is important in a variety of fields, including atmospheric chemistry, interstellar chemistry, crossed beam molecular collision studies, and Stark deceleration. In laboratory studies, OH is commonly detected with rotational state selectivity by measuring laser-induced fluorescence from ultraviolet A 2Σ + − X 2Π transitions. Previous studies have determined the absolute frequencies of these transitions to within approximately 0.003 cm−1 (100 MHz) a . This level of accuracy is quite sufficient for excitation with commonlyused frequency-doubled pulsed dye lasers, which typically have a bandwidth on the order of 0.1 cm−1 , but for driving the transitions with a continuous-wave (CW) laser with a linewidth on the order of 1 MHz or less, the transition frequencies must be known much more exactly. In this talk, I would like to present our recent high-precision measurements of the A 2Σ +, v0 = 0 ← X 2Π3/2, v00 = 0, J00 = 3/2 transitions in 16OH and 16OD. Using a frequency-doubled CW dye laser which is stabilized and monitored with the help of an optical frequency comb, we have measured transitions to the 12 lowest levels of the A 2Σ +, v0 = 0 vibronic state of 16OH with an uncertainty of less than 100 kHz (10−10 relative uncertainty) and are currently completing measurements of transitions to the 16 lowest A levels in 16OD with an expected uncertainty of 100–200 kHz. These measurements have enabled us to determine the 16OH A 2Σ +, v0 = 0 band origin with three orders of magnitude higher precision and the rotational constant with two orders of magnitude higher precision than previously possible. Similar improvements are expected in the corresponding constants of 16OD, as well as in its spin-rotation constant γ, which has not been measured in microwave double-resonance experiments as in 16OH b .

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100587

DOI

10.15278/isms.2018.MG03

Copyright and License Information

Copyright 2018 Samuel Meek

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