Speaker
Description
The $^1\text{P}_1 \leftarrow ^1\text{S}_0$ line in atomic cadmium shares many properties with the $^1\Pi \leftarrow ^1\Sigma^+$ laser cooling transition of the AlF molecule, making cadmium a convenient test system for laser cooling and trapping of AlF. In addition, cadmium possesses eight stable (six bosonic, two fermionic) isotopes, and a narrow spin-fobidden $^3\text{P}_1 \leftarrow ^1\text{S}_0$ transition, and is therefore an interesting atom to study in its own right. The isotope shifts of optical transitions provide a means to study the atomic nucleus, and are sensitive in particular to nuclear deformations. Until recently, robust narrow band laser light near the $^1\text{P}_1 \leftarrow ^1\text{S}_0$ transition wavelength of 229 nm was difficult to produce.
We produce a cold, slow beam of atomic Cd in a cryogenic buffer gas source, and use it to perform isotope-resolved laser induced fluorescence spectroscopy of the $^1\text{P}_1 \leftarrow ^1\text{S}_0$ and $^3\text{P}_1 \leftarrow ^1\text{S}_0$ lines. For the $^1\text{P}_1 \leftarrow ^1\text{S}_0$ transition, we use isotopically enriched samples and emission-angle selective detection to unambiguously determine the isotope shifts with MHz accuracy. In combination, these two techniques enable discriminating between fermionic and bosonic isotopes, whose transitions are poorly spectroscopically resolved due to the large natural linewidth of the transition. We show that for the fermionic isotopes, quantum interference is observable between the excited states, complicating the interpretation of the spectrum. After carefully accounting for quantum interference in the spectral lineshape of the fermions, we measured the radiative lifetime of the ${}^1\text{P}_1$ state as 1.60(5) ns. For the $^3\text{P}_1 \leftarrow ^1\text{S}_0$ transition, whose natural linewidth is three orders of magnitude smaller, it is straightforward to resolve the individual isotopes, and we benefit from the small Doppler shifts present in our slow atomic beam. We performed systematic checks to determine the accuracy of our transition frequency and isotope shift measurements, comparing to previously measured structure in cadmium, precisely known transitions in atomic copper, and an ultrastable optical cavity. This allows us to assign a systematic uncertainty to the isotope shifts of 3.3 MHz, sufficient for the application of our measurements in nuclear theory.
| Abstract Number (department-wise) | MP 14 |
|---|---|
| Department | MP (Meijer) |
