Measurement of the collisional self-broadening of the cesium6S1∕2→5D3∕2(689−nm)electric quadrupole transition

Abstract

We have measured the collisional self-broadening of the cesium $6{S}_{1∕2}\ensuremath{\rightarrow}5{D}_{3∕2}$ electric quadrupole $(E2)$ transition at $689\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ for temperatures from $220\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}370\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$, corresponding to cesium number densities from $3\ifmmode\times\else\texttimes\fi{}{10}^{15}\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}1.5\ifmmode\times\else\texttimes\fi{}{10}^{17}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. This $E2$ transition may have utility for studies of atomic parity nonconservation (PNC), and the collisional self-broadening represents an important systematic effect which must be understood for an accurate measurement of PNC. We find a value for this broadening of $1.32\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}\phantom{\rule{0.2em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, which is consistent with what would be expected for a quadrupole-quadrupole resonance interaction. To the best of our knowledge, no quantitative measurement of the self-broadening of an atomic $E2$ transition has been reported previously in the literature.