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Precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules

Abstract

In this thesis I report precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules where we use lasers to couple the states in different molecular potentials. We study in detail states of the a {sup 3} sum {sup +}{sub u} and (1) {sup 3} sum {sup +}{sub g} potentials. These states are of great importance for transferring weakly bound molecules to the ro-vibrational triplet ground state via states of the excited potential. As most experiments start from molecules in their X {sup 1} sum {sup +}{sub g} ground state, the triplet states were hard to access via dipole transitions and remained largely unexplored. The measurements presented in this thesis are the first detailed study of diatomic {sup 87}Rb{sub 2} molecules in these states. Our experiments start with an ultracold cloud of {sup 87}Rb atoms. We then load this cloud into an optical lattice where we use a magnetic Feshbach resonance at 1007.4 G to perform a Feshbach association. After we have removed all unbound atoms, we end up with a pure sample of weakly bound Feshbach molecules inside the optical lattice. The optical lattice prevents these molecules from colliding with each other which results in molecular lifetimes on the order  More>>
Publication Date:
Oct 19, 2011
Product Type:
Thesis/Dissertation
Report Number:
INIS-DE-1246
Resource Relation:
Other Information: TH: Diss. (Dr.rer.nat.)
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; BOUND STATE; DIMERS; EXPERIMENTAL DATA; GROUND STATES; HYPERFINE STRUCTURE; M1-TRANSITIONS; MOLECULES; ROTATIONAL STATES; RUBIDIUM; RUBIDIUM 87; SPECTRA; TRIPLETS; VIBRATIONAL STATES; ZEEMAN EFFECT
OSTI ID:
21539006
Research Organizations:
Ulm Univ. (Germany). Fakultaet fuer Naturwissenschaften
Country of Origin:
Germany
Language:
English
Other Identifying Numbers:
TRN: DE12F4024
Availability:
OSTI as DE21539006; Commercial reproduction prohibited; INIS
Submitting Site:
DEN
Size:
134 pages
Announcement Date:
Mar 28, 2012

Citation Formats

Strauss, Christoph. Precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules. Germany: N. p., 2011. Web.
Strauss, Christoph. Precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules. Germany.
Strauss, Christoph. 2011. "Precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules." Germany.
@misc{etde_21539006,
title = {Precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules}
author = {Strauss, Christoph}
abstractNote = {In this thesis I report precision spectroscopy with ultracold {sup 87}Rb{sub 2} triplet molecules where we use lasers to couple the states in different molecular potentials. We study in detail states of the a {sup 3} sum {sup +}{sub u} and (1) {sup 3} sum {sup +}{sub g} potentials. These states are of great importance for transferring weakly bound molecules to the ro-vibrational triplet ground state via states of the excited potential. As most experiments start from molecules in their X {sup 1} sum {sup +}{sub g} ground state, the triplet states were hard to access via dipole transitions and remained largely unexplored. The measurements presented in this thesis are the first detailed study of diatomic {sup 87}Rb{sub 2} molecules in these states. Our experiments start with an ultracold cloud of {sup 87}Rb atoms. We then load this cloud into an optical lattice where we use a magnetic Feshbach resonance at 1007.4 G to perform a Feshbach association. After we have removed all unbound atoms, we end up with a pure sample of weakly bound Feshbach molecules inside the optical lattice. The optical lattice prevents these molecules from colliding with each other which results in molecular lifetimes on the order of a few hundred milliseconds. In the first set of experiments, we use a laser coupling the Feshbach state to the excited (1) {sup 3} sum {sup +}{sub g} triplet state to map out its low-lying vibrational (v = 0.. 15), rotational, hyperfine, and Zeeman structure. The experimental results are in good agreement with calculations done by Marius Lysebo and Prof. Leif Veseth. We then map out in detail the vibrational, rotational, hyperfine, and Zeeman structure of the a {sup 3} sum {sup +}{sub u} triplet ground state using dark state spectroscopy with levels in the (1) {sup 3} sum {sup +}{sub g} potential as an intermediate state. In this scheme we are able to access molecules in triplet states because our Feshbach state has strong triplet character. Interestingly, it happens that some deeply bound states which belong to the X {sup 1} sum {sup +}{sub g} potential are close to levels in the a {sup 3} sum {sup +}{sub u} potential. In these cases it was possible to directly observe singlet-triplet mixing at binding energies as deep as a few hundred GHz x h, where h is Planck's constant. Prof. Eberhard Tiemann calculated the energies using a coupledchannel code. After several iterations between measurements and optimization of the potentials, it turned out that the hyperfine and effective spin-spin interactions depend weakly on the vibrational level. With the help of Eberhard Tiemann it also became possible to reassign some Feshbach resonances measured previously. In general we find excellent agreement between theory and experiment to within the experimental error of 50 MHz. A detailed understanding of the two triplet potentials is important as we want to study the collisional behavior of molecules in the triplet ground state. Depending on the elastic and inelastic scattering cross sections, it could then become possible to condense these molecules and create a molecular Bose-Einstein condensate. (orig.)}
place = {Germany}
year = {2011}
month = {Oct}
}