A new type of compact magnesium cell with room-temperature walls have been developed for high resolution spectroscopy on the Mg 1S0-3P1 intercombination line. Saturation resonances with a FWHM of 1.3.MHz have been detected in this cell in the fluorescence signal. The time selection method was applied to eliminate the background signal caused by the scattering of laser beams on cell windows. The signal-to-background ratio drastically increased by the spatial localization of excited atoms owing to collisions with atoms of a low-pressure inert gas.
An experiment is reported in which an intense laser is used to cause the intercombination transfer of metastable
1s2s2p4P25 atoms to the $1s2{p}^{2}^{2}P_{\frac{3}{2}}$ level with subsequent radiation in the extreme ultraviolet, thereby providing the first direct tie between the quartet and doublet manifolds in neutral Li. Intercombination transfer between the triplet and singlet manifolds of
Li+ and tunable anti-Stokes radiation centered near 199 \AA{} are also described.
We report on progress of generating ultracold atoms of magnesium. Magnesium belongs to the few elements suited for a neutral atom optical frequency standard. Its unique properties such as a very low black body radiation shift, the occurrence of fermionic and bosonic isotopes of suitable abundance, and the existence of a magic wavelength make it a very attractive candidate for future optical clocks. With our experiment, we determined for the first time the absolute frequency of the intercombination transition 31S0? 33P1of24Mg with a Ramsey-Bord Enterferometer, which was linked to a primary Cs Frequency standard of the PTB via a fiber femtosecond laser. Cooling ensembles of magnesium in the non-magnetic ground state to microkelvins is difficult as standard sub-Doppler cooling schemes are not applicable. We investigate novel methods to lower the temperatures of magnesium atoms. One promising method is based on a coherent two photon-process which provides higher velocity selectivity. Alternatively, standard sub-Doppler cooling schemes are applicable to the long-lived excited state, which in addition can be confined in magnetic traps. Article not available.
We have measured the lifetime of the
3P1 metastable state of Mg and obtained a value of 2.2 \ifmmode\pm\else\textpm\fi{} 0.2 msec. The level was excited with a dye laser tuned to the intercombination line ($3s3p^{3}P_{1}\ensuremath{\leftrightarrow}3{s}^{2}^{1}S_{0}$). In addition to the
3P1 state, the
3P2 and
3P0 levels were populated by mixing collisions owing to the presence of an inert buffer gas. The populations of all three metastable levels were monitored as a function of time by observing the absorption of Mg resonance radiation ($^{3}P_{0,1,2}\ensuremath{\rightarrow}^{3}S_{1}$) out of each level. The mixing time was short compared to the
3P1 lifetime, so that the populations of the three metastable levels were in thermal equilibrium with each other. This produced an apparent lengthening of the
3P1 lifetime, which would introduce a large systematic error if the degree of mixing were not known. Cenventionally, one observes the fluorescence from the excited levels to obtain their lifetimes. Because the lifetimes of the
3P2 and
3P0 states are too long, fluorescence from these states cannot be observed, and the observation of fluorescence from the
3P1 state alone provides insufficient information to determine its lifetime.
This Communication describes a novel spectroscopic technique for studying high-lying atomic states. The approach uses two cw narrow-band stabilized dye lasers configured in a four-wave-mixing geometry. We demonstrate that the measurements are Doppler-free and the method is capable of high resolution. Using this technique we examine the complex dephasing parameter ${\ensuremath{\gamma}}_{\mathrm{ij}}$ associated with buffer-gas collisions in atomic sodium. Rates for pressure-induced broadening and resonance shifts are reported for neon.
We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of the alkali atoms; which enables the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal defection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.