University of Illinois Urbana-Champaign

Rydberg Spectroscopy Of Zeeman-decelerated Beams Of Metastable Helium Molecules

Jansen, Paul

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RH06_Abstract.pdf
RH06_Abstract.txt
RH06_Presentation.pdf

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https://hdl.handle.net/2142/51038

Description

Title
Rydberg Spectroscopy Of Zeeman-decelerated Beams Of Metastable Helium Molecules
Author(s)
Jansen, Paul
Contributor(s)
  • Merkt, Frederic
  • Sprecher, Daniel
  • Motsch, Michael
Issue Date
2014-06-19
Keyword(s)
Cold/Ultra-cold/Physics
Date of Ingest
  • 2014-09-17T16:55:53Z
  • 2015-04-14T18:42:22Z
Abstract
"Having three and four electrons, respectively, He$_2^+$ and He$_2$ represent systems for which highly accurate \textit{ab-initio} calculations might become feasible in the near future\footnote{W.-C. Tung, M. Pavanello, L. Adamowicz, \textit{J. Chem. Phys.} \textbf{136}, 104309 (2012).}. With the goal of performing accurate measurements of the rovibrational energy-level structure of He$_2^+$ by Rydberg spectroscopy of He$_2$ and multichannel quantum-defect theory extrapolation techniques\footnote{D. Sprecher, J. Liu, T. Kr\""ahenmann, M. Sch\""afer, and F. Merkt, \textit{J. Chem. Phys.} \textbf{140}, 064304 (2014).}, we have produced samples of helium molecules in the $a ^3\Sigma_\mathrm{u}^+$ state in supersonic beams with velocities tunable down to 100\,m/s by combining a cryogenic supersonic-beam source with a multistage Zeeman decelerator\footnote{M. Motsch, P. Jansen, J. A. Agner, H. Schmutz, and F. Merkt, \textit{arXiv:1401.7774}.}. The molecules are formed at an initial velocity of 500 m/s by striking a discharge in the pulsed expansion of helium gas from a reservoir kept at a cryogenic temperature of 10 K. Using rotationally-resolved PFI-ZEKE (pulsed-field-ionization zero-kinetic-energy) photoelectron spectroscopy, we have probed the rotational-state distribution of the molecules produced in the discharge and found vibrational levels up to $\nu'' = 2$ and rotational levels up to $N''=21$ to be populated. The molecular beam is coupled to a multistage Zeeman decelerator\footnote{N. Vanhaecke, U. Meier, M. Andrist, B. H. Meier, and F. Merkt, \textit{Phys. Rev. A} \textbf{75}, 031402(R) (2007).} that employs pulsed inhomogeneous magnetic fields to further reduce the beam velocity. By measuring the quantum-state distribution of the decelerated sample using photoelectron and photoionization spectroscopy we observed no rotational or vibrational state-selectivity of the deceleration process, but found that one of the three spin-rotation components of the He$_2$ $a ^3\Sigma_\mathrm{u}^+$ rotational levels is eliminated."
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
English
Permalink
http://hdl.handle.net/2142/51038
DOI
https://doi.org/10.15278/isms.2014.RH06
Copyright and License Information
Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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Abstracts & Presentations - 2014 International Symposium on Molecular Spectroscopy PRIMARY