Ian C. Stevenson | Searcharxiv

arXiv2019

Measurement of the lifetime of the $7s^2S_{1/2} $ state in atomic cesium using asynchronous gated detection

We report a measurement of the lifetime of the cesium $7s\,^2S_{1/2}$ state using time-correlated single-photon counting spectroscopy in a vapor cell. We excite the atoms using a Doppler-free two-photon transition from the $6s\,^2S_{1/2}$ ground state, and detect the 1.47$μ$m photons from the spontaneous decay of the $7s\,^2S_{1/2}$ to the $6p\,^2P_{3/2}$ state. We use a gated single photon detector in an asynchronous mode, allowing us to capture the fluorescence profile for a window much larger than the detector gate length. Analysis of the exponential decay of the photon count yields a $7s\,^2S_{1/2}$ lifetime of 48.28$\pm$0.07ns, an uncertainty of 0.14%. These measurements provide sensitive tests of theoretical models of the Cs atom, which play a central role in parity violation measurements.

physics.atom-ph↗

arXiv2016

Short-range Photoassociation of LiRb

We have observed short-range photoassociation of LiRb to the two lowest vibrational states of the $d\,^3Π$ potential. These $d\,^3Π$ molecules then spontaneously decay to vibrational levels of the $a^3\,Σ^+$ state with generation rates of $\sim10^3$ molecules per second. This is the first observation of many of these $a\,^3Σ^+$ levels. We observe an alternation of the peak heights in the rotational photoassociation spectrum that suggests a $p$-wave shape resonance in the scattering state. Franck-Condon overlap calculations predict that photoassociation to higher vibrational levels of the $d\,^3Π$, in particular the sixth vibrational level, should populate the lowest vibrational level of the $a\,^3Σ^+$ state with a rate as high as $10^4$ molecules per second. These results encourage further work to explain our observed LiRb collisional physics using PECs. This work also motivates an experimental search for short-range photoassociation to other bound molecules, such as the $c\,^3Σ^+$ or $b\,^3Π$, as prospects for preparing ground-state molecules.

physics.atom-ph↗