Cooling of electronically-excited He2 molecules in a microcavity plasma jet

Su, Rui

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https://hdl.handle.net/2142/91477 Copy

Description

Title

Cooling of electronically-excited He2 molecules in a microcavity plasma jet

Author(s)

Su, Rui

Contributor(s)

• Eden, J. Gary
• Houlahan, Thomas J., Jr.

Issue Date

2016-06-24

Keyword(s)

Dynamics and kinetics

Abstract

Helium dimers in the d$^{3}\Sigma^{+}_{u}$ excited electronic state with potential energy $>$24 eV and radiative lifetime of 25 ns have been generated in a microcavity plasma jet and rotationally cooled by supersonic expansion in vacuum. The dynamic process of cooling is recorded by imaging the axis of expansion onto the slit of Czerny-Turner spectrometer, yielding spatial-temporal spectrograms of d$^{3}\Sigma^{+}_{u}$$\rightarrow$$b^{3}\Pi_{g}$ $(v', v'')=(0, 0)$ emission. Analysis of the data shows the spatial-temporal evolution of the rotational temperature to be a damped sinusoid that reaches a minimum value of 100K. This reproducible behavior is attributed to the reflection of electrons from a virtual cathode located downstream of the nozzle and indicates that the spatially-averaged electron density is 10$^{8}$ cm$^{-3}$. We present this observed rotational temperature oscillation during the supersonic cooling process as an example of the potential of our supersonic microplasma expansion as a tool to explore physical dynamics in diatomic molecules having high excitation energies and small lifetimes.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

En

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http://hdl.handle.net/2142/91477

Copyright and License Information

Copyright 2016 by the authors

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