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Title: | Rydberg Spectroscopy Of Zeeman-decelerated Beams Of Metastable Helium Molecules |
Author(s): | Jansen, Paul |
Contributor(s): | Merkt, Frederic; Sprecher, Daniel; Motsch, Michael |
Subject(s): | Cold/Ultra-cold/Physics |
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. |
Issue Date: | 2014-06-19 |
Publisher: | International Symposium on Molecular Spectroscopy |
Citation Info: | Jansen, P.; Merkt, F.; Sprecher, D.; Motsch, M. RYDBERG SPECTROSCOPY OF ZEEMAN-DECELERATED BEAMS OF METASTABLE HELIUM MOLECULES. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.RH06 |
Genre: | CONFERENCE PAPER/PRESENTATION |
Type: | Text |
Language: | English |
URI: | http://hdl.handle.net/2142/51038 |
DOI: | https://doi.org/10.15278/isms.2014.RH06 |
Rights Information: | Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/ |
Date Available in IDEALS: | 2014-09-17 2015-04-14 |