We provide a detailed description of our fast-beam laser lifetime measurements in atomic cesium. Selective excitation of the neutral
133Cs 6p2P1/2 and
6p2P3/2 states is accomplished with resonant diode laser light directed transversely to the atomic velocity. The in-flight decay of the excited-state fluorescence is observed with a position-correlated single photon-counting detector. The Doppler-shifted
6p2P3/2 resonance, when probed with longitudinally propagating laser radiation, provides a precise means for determination of the beam velocity, and converts the position scale to a time scale. Our lifetime results are $35.07\ifmmode\pm\else\textpm\fi{}0.10 \mathrm{ns}$ for the
6p2P1/2 state and $30.57\ifmmode\pm\else\textpm\fi{}0.07 \mathrm{ns}$ for the
6p2P3/2 state. These results represent a data set larger than in our previous work, and include beam divergence corrections which have been evaluated by two different methods. We present comparisons of our results with previous measurements and with relativistic many-body calculations of atomic transition matrix elements in this neutral alkali system.
We report a measurement of the ratio of electric dipole transition matrix elements of cesium for the $6p{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}\ensuremath{\rightarrow}7s{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}$ and $6p{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{3/2}\ensuremath{\rightarrow}7s{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}$ transitions. We determine this ratio of matrix elements through comparisons of two-color, two-photon excitation rates of the
7s2S1/2 state using laser beams with polarizations parallel to one another vs perpendicular to one another. Our result of $R\ensuremath{\equiv}\ensuremath{\langle}7s{\phantom{\rule{4pt}{0ex}}}^{2}{S}_{1/2}||r||6p{\phantom{\rule{4pt}{0ex}}}^{2}{P}_{3/2}\ensuremath{\rangle}/\ensuremath{\langle}7s{\phantom{\rule{4pt}{0ex}}}^{2}{S}_{1/2}||r||6p{\phantom{\rule{4pt}{0ex}}}^{2}{P}_{1/2}\ensuremath{\rangle}=1.5272(17)$ is in excellent agreement with a theoretical prediction of
R=1.5270(27). Moreover, the accuracy of the experimental ratio is sufficiently high to differentiate between various theoretical approaches. To our knowledge, there are no prior experimental measurements of
R. Combined with our recent determination of the lifetime of the
7s2S1/2 state, we determine reduced matrix elements for these two transitions, $\ensuremath{\langle}7s{\phantom{\rule{4pt}{0ex}}}^{2}{S}_{1/2}||r||6p{\phantom{\rule{4pt}{0ex}}}^{2}{P}_{3/2}\ensuremath{\rangle}=\ensuremath{-}6.489(5)\phantom{\rule{4pt}{0ex}}{a}_{0}$ and $\ensuremath{\langle}7s{\phantom{\rule{4pt}{0ex}}}^{2}{S}_{1/2}||r||6p{\phantom{\rule{4pt}{0ex}}}^{2}{P}_{1/2}\ensuremath{\rangle}=\ensuremath{-}4.249(4)\phantom{\rule{4pt}{0ex}}{a}_{0}$. These matrix elements are also in excellent agreement with theoretical calculations. These measurements improve knowledge of Cs properties needed for parity violation studies and provide benchmarks for tests of high-precision theory.
Analysis of the relative angular response of the degenerate four-wave mixing signal in alkali-metal atoms mixed with a buffer gas allows direct determination of the excited-state diffusion coefficients. The measured diffusion coefficients D at 96 \ifmmode^\circ\else\textdegree\fi{}C and 760 torr for the cesium 6
P1/2 and 6
P3/2 state atoms in neon gas are 0.348(4)
cm2 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ and 0.281(8)
cm2 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, respectively. \textcopyright{} 1996 The American Physical Society.