H₂O AND HDO TEMPERATURE DEPENDENT LINESHAPES USING SUB-DOPPLER METHODS

Drouin, Brian

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https://hdl.handle.net/2142/122660 Copy

Description

Title

H₂O AND HDO TEMPERATURE DEPENDENT LINESHAPES USING SUB-DOPPLER METHODS

Author(s)

Drouin, Brian

Contributor(s)

• Lis, D. C.
• Von Allmen, Paul
• Crawford, Timothy J.
• Nemchick, Deacon J

Issue Date

2023-06-20

Keyword(s)

Astronomy

Abstract

Collisional energy transfer in volatized exospheric materials dominates the uncertainty of comet models that trace comae composition back to surface composition. Methods for ab initio and semi-empirical calculation of quantum-state dependent collisional efficiencies are typically benchmarked to pressure broadening experiments when available. Last year we detailed experimental efforts to determine collisional efficiencies for selected transitions of water at temperatures demonstrative of the comet environment and well below the water condensation temperature. This year we add two HDO transitions to the data set. The method utilizes a collisional cooling cell with water and/or deuterated water injected into a bath gas at the target temperature or held at temperatures that produce relevant vapor pressures for measurement. THz radiation is passed twice through the cooled gas to record a transmission spectrum exhibiting the Lamb dip effect. The sub-Doppler feature is subject to collisional broadening at pressures commensurate with the partial pressure of water and deuterated water in the system. Data analysis involves extraction of intensity and pressure broadening information. The method, results and comparisons to calculated values will be discussed.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122660

DOI

https://doi.org/10.15278/isms.2023.7189

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