Measurement of the collisional self-broadening of the cesium 6S_1∕2→5D_3∕2 (689-nm) electric quadrupole transition

We have measured the collisional self-broadening of the cesium 6S_1∕2→5D_3∕2 electric quadrupole (E2) transition at 689 nm for temperatures from 220 to 370 °C, corresponding to cesium number densities from 3×10¹⁵ to 1.5×10¹⁷ cm⁻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±0.06×10⁻⁸ cm³ s⁻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.