Dispenser Source Research Articles

On the continuous loading of a U-magneto-optical trap on an atom-chip in an ultra high vacuum

Here, we report our studies on the continuous loading of a U-magneto-optical trap (U-MOT) on an atom-chip with a rubidium-(Rb)-vapor-generated background using a dispenser source in an ultra high vacuum environment. Using the U-MOT loading curves, the partial pressure due to the Rb vapor and the pressure due to the background gas have been estimated near the MOT cloud position. The estimated pressure due to the Rb vapor increased from ∼ Torr to Torr as the Rb-dispenser current was increased from 2.8 to 3.4 A. The increase in dispenser current also resulted in a decrease in loading time as well as the lifetime of the MOT cloud. This study will be useful for magnetic trapping experiments where accurate information of the pressure in a chamber is important for the lifetime of the magnetic trap.

A NEW SETUP FOR THE STUDY OF ADSORPTION/DESORPTION PROCESSES AND NANOPARTICLES FORMATION IN POROUS ALUMINA

We present a setup devoted to the study of adsorption and desorption processes of alkali atoms after deposition on a 300 nm thick porous alumina substrate in an Ultra High Vacuum chamber. Rubidium atoms, delivered by a dispenser source, enter the 20-30 nm diameter pores, diffuse in and stick to their walls. A 1 W power laser is used in order to induce detachment and take the atoms back in the vapor phase in a very tight confinement region. The desorbed atoms coming out the sample can be monitored via both a resonant optical detection and an electronic amplifier after ionization. The desorbing laser is also able to promote the formation of Rubidium nanoparticles, as the high Rb vapor density in the pores favors aggregation around nucleation point defects. In this way, the apparatus allows for the study of the fundamental processes related to atom – surface interactions in presence of light as well as of several promising application to nanomaterials.

Single-beam Zeeman slower and magneto-optical trap using a nanofabricated grating.

We demonstrate a compact (0.25 L) system for laser cooling and trapping atoms from a heated dispenser source. Our system uses a nanofabricated diffraction grating to generate a magnetooptical trap (MOT) using a single input laser beam. An aperture in the grating allows atoms from the dispenser to be loaded from behind the chip, increasing the interaction distance of atoms with the cooling light. To take full advantage of this increased distance, we extend the magnetic field gradient of the MOT to create a Zeeman slower. The MOT traps approximately 106 7Li atoms emitted from an effusive source with loading rates greater than 106 s-1. Our design is portable to a variety of atomic and molecular species and could be a principal component of miniaturized cold-atom-based technologies.

A compact atomic beam based system for Doppler-free laser spectroscopy of strontium atoms.

We report the construction of a simple, light weight, and compact atomic beam spectroscopy cell for strontium atoms. The cell is built using glass blowing technique and includes a simple titanium sublimation pump for the active pumping of residual and background gases to maintain ultra-high vacuum. A commercially available and electrically heated dispenser source is used to generate the beam of Sr atoms. We perform spectroscopy on the 5s2S01→5s 5pP11 transition to obtain a well resolved Doppler free spectroscopic signal for frequency stabilization of the laser source. This design can be easily extended to other alkali and alkaline earth metals.

Trap Capture of Brown and Dusky Stink Bugs (Hemiptera: Pentatomidae) as Affected by Pheromone Dosage in Dispensers and Dispenser Source

Brown, Euschistus servus (Say), and dusky, E. tristigmus (Say), stink bugs (Heteroptera: Pentatomidae) readily respond to traps baited with the Euschistus spp. aggregation pheromone methyl (E, Z) -2,4-decadienoate. Previous studies examining trap capture of these stink bugs have used either laboratory-prepared dispensers or commercial dispensers with various known and unknown pheromone doses. We compared trap captures of E. servus and E. tristigmus using yellow pyramid traps baited with a range of pheromone doses (20 - 120 μL) loaded onto rubber septa and when baited with 2 commercially available pheromone dispensers. These baited traps were located primarily in or alongside pecan orchards with one exception being alongside a peach/plum orchard. Traps were monitored weekly for 4 wk during 2008 and 2009. Dispensers were either replaced weekly or the same dispenser remained in use for the entire study. All pheromone doses tested resulted in a numerical increase of both E. servus and E. tristigmus captured in traps compared with traps using no pheromone. In each experiment for each species, at least one pheromone dose significantly increased trap capture compared with traps using a septa containing no pheromone. In direct comparisons, neither commercial dispenser ever captured significantly more E. servus or E. tristigmus than traps without pheromone. Numerically higher trap captures were observed with a higher pheromone dose in each of 5 month-long studies. However, captures were not always significantly higher for either species suggesting that other factors affected stink bug capture in pheromone-baited traps. Results from this study could facilitate the use of this stink bug trap as a barrier to impede movement of pest Euschistus spp. into orchards or other crop habitats.

Integrated atom detector based on field ionization near carbon nanotubes

We demonstrate an atom detector based on field ionization and subsequent ion counting. We make use of field enhancement near tips of carbon nanotubes to reach extreme electrostatic field values of up to 9x10^9 V/m, which ionize ground state rubidium atoms. The detector is based on a carpet of multiwall carbon nanotubes grown on a substrate and used for field ionization, and a channel electron multiplier used for ion counting. We measure the field enhancement at the tips of carbon nanotubes by field emission of electrons. We demonstrate the operation of the field ionization detector by counting atoms from a thermal beam of a rubidium dispenser source. By measuring the ionization rate of rubidium as a function of the applied detector voltage we identify the field ionization distance, which is below a few tens of nanometers in front of nanotube tips. We deduce from the experimental data that field ionization of rubidium near nanotube tips takes place on a time scale faster than 10^(-10)s. This property is particularly interesting for the development of fast atom detectors suitable for measuring correlations in ultracold quantum gases. We also describe an application of the detector as partial pressure gauge.

A vapor cell based on dispensers for laser spectroscopy

We describe a simple strontium vapor cell for laser spectroscopy experiments. Strontium vapor is produced using an electrically heated commercial dispenser source. The sealed cell operates at room temperature, and without a buffer gas or vacuum pump. The cell was characterized using laser spectroscopy, and was found to offer stable and robust operation, with an estimated lifetime of >10 000 h. By changing the dispenser, this technique can be readily extended to other alkali and alkaline earth elements.

Novel rubidium atomic beam with an alkali dispenser source

We describe a novel atomic beam apparatus with a resistively heated alkali dispenser source and a cold-pumped intermediate chamber. Using laser fluorescence spectroscopy we have measured the atomic density to be 3×1011atoms∕m3 and the total flux to be 5×108atoms∕s in a 0.3cm diameter beam. We have also characterized the velocity distribution of the source based on the Doppler-shifted fluorescence spectrum. The compact geometry, flexibility, and simplicity of the beam may make it useful as an optical frequency reference or for experiments on atom-cooling.

Potassium adsorption on hydrogen- and oxygen-terminated diamond(100) surfaces

Abstract The adsorption of K at 298 K is a route for the titration of surface groups like O and OH. The experiments were performed on a semi-conducting natural diamond (100) surface cleaned by a 480-W microwave hydrogen plasma at 750°C and a hydrogen pressure of 20 mbar, resulting in a very clean, ordered (2×1) surface. A second type of C(100) surface was prepared by ex situ oxidation, using a mixture of hydrochloric and nitric acids. The adsorption experiments were carried out in a UHV system equipped with facilities for photoelectron spectroscopy (XPS and UPS). K deposition was achieved using a dispenser source from the SAES Getters Company. The K uptake of H-terminated C(100) at room temperature is marginal, with a sticking coefficient of

Chemical interaction of Na with cleaved (011) surfaces of CuInSe2

To study the beneficial effect of sodium-containing substrate material on the photovoltaic properties of thin-film CuInSe2 solar cells the chemical interaction of Na with CuInSe2 has been investigated by synchrotron excited photoelectron spectroscopy. A clean CuInSe2 (011) surface was prepared by cleaving an oriented single crystal in UHV. The cleaved surface exhibits an electron affinity of χ≊4.6 eV. The Se 3d level shows a surface core level shift of −0.4 eV. Na was sequentially deposited in UHV in small steps from a commercial dispenser source. Initially ionized Na adsorbs on the surface leading to a shift of the surface Fermi level by 0.3 eV closer to the conduction band. Removal of Cu from the surface is observed. For higher Na deposition a chemical reaction of Na with the CuInSe2 surface occurs leading to the formation of metallic indium and Na2Se.

Ion emission from a dispenser source with sodium silicate matrix

Ion emission from a dispenser source with sodium silicate matrix