C. Marinelli

Magnetic coherence resonance profiles in Na and K

Magnetic coherence resonance profiles, obtained at magetic field B = O in Hanle configuration were examined for Na and K atoms in different cells: evacuated glass cells and buffered, coated and uncoated. At low laser power for all cells the shape of the resonancees is Lorentzian. At power higher than about 100 mW/cm2, some narrowing around the resonance peak is observed for the Na buffered cell, while for the vacuum one the resonance shape is even more complex. Theoretical explanation is proposed for the complex resonance shape evidenced in the vacuum cells. Large resonance contrast in the K absorption at B = 0 is observed, attributed to the low rate of hyperfine optical pumping in K. The detailed investigation of the resonance profiles and contrast is of very high importance for their application.

Lossless formation of electromagnetically induced transparency in sodium atoms

In this paper we propose a simple method for eliminating the population losses of MC resonances by involving all atoms of the Na ground state in the formation of the narrow coherent resonances observed in the fluorescence when scanning around zero value the applied magnetic field. As a result, dark resonances with a contrast up to 100% have been observed. Results are obtained in two different experimental configurations: using laser excitation of linear and circular polarization, leading to different population redistribution among Zeeman and hf levels. Theoretical analysis of the results is also presented. It is shown that at certain conditions complete optical pumping of atoms to levels Fg=2, mFg=2 or mFg=-2 can be achieved, which means complete orientation of the atoms.

Transformation of electromagnetically induced transparency into absorption in a thermal potassium optical cell with spin preserving coating

We report a new experimental approach where an order of magnitude enhancement of the electromagnetically induced absorption (EIA) resonance contrast, thus making it similar to that of the EIT resonance contrast is observed under the same conditions. The EIA signal results from the interaction of a weak probe beam with a ground state that has been driven by the pump (counter-propagating) beam. Probe absorption spectra are presented where the laser frequency is slowly detuned over the D1 line of 39K vapor contained in a cell with a PDMS antirelaxation coating. In addition to the frequency detuning, a magnetic field orthogonal to the laser beams is scanned around zero value at a higher rate. With both laser beams linearly polarized, an EIT resonance is observed. However, changing the pump beam polarization from linear to circular reverses the resonance signal from EIT to EIA.

Coherent Spectroscopy of Sodium and Potassium Vapour

A brief introduction is presented related to three different approaches for Coherent Population Trapping (CPT) observation, namely CPT resonance prepared: (i) in degenerate two‐level system, (ii) by coupling pairs of non‐degenerate Zeeman sublevels of two ground levels and (iii) utilizing Zeeman sublevels within a single hyperfine transition. As an illustration of the first two approaches recent results concerning the CPT preparation on the first resonance line in Na and K are described. The first, to our best knowledge, CPT resonance observation on the second resonance line of K (violet, 404.4 nm) is reported. A transfer of the CPT resonance due to cascade transitions, without compromising its parameters, is evidenced. The presented results are promising for investigation of processes in atomic vapour and gas discharge.

HgIn excimer and bound-bound emission following laser excitation of atomic In in an indium-mercury vapor mixture

Laser excitation of the In(62S1/2−52P1/2) atomic transition in a Hg-In-Ne gaseous mixture results in HgIn excimer emission near the In atomic resonance lines at 410.3 nm and 451.1 nm as well as HgIn bound-bound transitions at 499 nm and 522 nm. The spectrum, including the fluorescence lifetimes of the various features, are interpreted in terms of analagous states extrapolated from high resolution spectroscopic observations of HgTl.

Coherent spectroscopy in Cs for precise magnetic field measurements

Investigation on coherent population trapping and electromagnetic induced absorption effects has been made in Cs vapors. A detailed analysis of degenerate and non-degenerate cases is reported. Possible application to precise magnetic field measurements is discussed and preliminary results described.

Temperature dependence of coherent resonances in Na and Cs cells

Temperature dependences of coherent resonances in Na and Cs atoms prepared by two coherent laser frequencies or two polarizations of single frequency laser field are presented. It is shown that the temperature dependence of the amplitude or contrast of the resonances in most cases exhibits a maximum. For both types of coherent resonances, a reason for the contrast reduction at higher temperature is the increased absorption of the laser light along the gas cell due to the optical thickness of the medium. Spin-exchange collisions lead to resonance contrast reduction more effectively in a cell with pure alkali atoms.

Laser cooling and trapping of radioactive atoms

Laser cooling and trapping techniques made possible during the last two decades important achievements in the atomic physics and quantum mechanics fields. These same techniques can be usefully applied to radioactive atoms by opening new fields of investigations. Nuclear processes can be studied with the atomic physics tools. We focused our attention on Francium radioactive atoms. A magneto-optical trap has been set up at the INFN Legnaro laboratories. Preliminary tests with other stable alkali atoms aimed at an improvement of the MOT collection efficiency are reported. Fast and efficient trap loading of rubidium has been obtained through the light-induced atomic desorption from an organic coating. A larger number of sodium atoms, as compared to monochromatic trapping laser, has been trapped by using a broad-band laser.

Electronic transitions in In2

Electronic emission bands of In2 are generated (a) in a microwave discharge in a quartz cell containing the metal plus a low pressure of Ar or Ne and (b) by radiative combination of In atoms excited to the 6SS1fl state with In atoms in the ground (52P1) state. In (a) a band progression to high energies was observed commencing at 25 730 cm1 which can be fit by moelcular constants of ue 105.3 cm1, COXe 26.2 cm1, and De 212 cm1. In (b) strong, unresolved, overlaped band features were observed in the 380 nm wavelength region (25 500 cm1 to 27 000 cm ) and a weaker, broad feature at 375 cm1 (28 300 cm1 to 30 000 cm1).