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CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1849
DTSTART:20100513T190000Z
DURATION:PT1H0M0S
DTSTAMP:20260415T102637Z
LAST-MODIFIED:20100419T145234Z
LOCATION:5280 Chamberlin
SUMMARY:Polarization and hyperfine transitions of metastable <sup>129<
 /sup><i>Xe</i> in discharge cell\, & Nonlinear Pressure Shifts of Cs A
 toms in Neon\, Atomic Seminar\, Tian Xia\, Princeton University
DESCRIPTION:<p>Part I: Polarization and hyperfine transitions of metas
 table <sup>129</sup><i>Xe</i> in discharge cell</p>
\n<p>The polarizat
 ion and relaxation rates of metastable <sup>129</sup><i>Xe</i> atoms a
 re measured with magnetic resonance spectroscopy\, at both microwave f
 requencies\, where Δ<i>F</i> = 1 transitions are induced between the 
 sublevels\, and at radiofrequencies\, corresponding to Δ<i>F</i> = 0 
 transitions. Unlike earlier work\, which mostly used Δ<i>F</i> = 0 ra
 diofrequency (rf) resonances for monitoring spin polarization of even 
 isotopes of the metastable atoms\, the
\nwork reported here was focuse
 d on the isotope <sup>129</sup><i>Xe</i> \, where we used both Δ<i>F<
 /i> = 0 rf
\nresonances and Δ <i>F</i> = 1 microwave resonances. This
  permits us to more unambiguously determine the degree of nuclear spin
  polarization of the optically pumped metastable atoms. The nuclear sp
 in polarization of the resonant velocity group is measured to be 22 +/
 - 2%. The relaxation of metastable xenon atoms is dominated by depolar
 izing collisions with ground
\nstate atoms\, with lesser contributions
  from metastability exchange collisions.</p>
\n<p>Part II: Nonlinear P
 ressure Shifts of Cs Atoms in Neon</p>
\n<p>I demonstrate that the hyp
 erfine resonance frequency of ground state Cs atoms have a nonlinear d
 ependence on the pressure of the buffer gas Ne at a fixed temperature.
  The hyperfine resonance frequency of alkali-metal atoms is shifted by
  an amount\, which had long been assumed to be linear with the buffer 
 gas pressure until Fei Gong discovered that the shift of Rb and Cs hyp
 erfine resonance frequency has a nonlinear dependence on the pressure 
 of
\nthe buffer gas Ar and Kr. I found that the nonlinear pressure shi
 ft of Cs hyperfine frequency in Ne is positive. The reason of the nonl
 inear shift is the three body collision (eg: Cs-Ne-Ne)
\nand the forma
 tion of Van der Waals molecules of a Cs atom and a buffer gas atom of 
 Ar\, Kr\, or Ne. The hyperfine precession rate of a Cs atom bound in m
 olecule has a shift respect to a free Cs atom.
URL:https://www.physics.wisc.edu/events/?id=1849
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