Dynamical Processes in Rydberg-Stark Deceleration and Trapping of Atoms and Molecules

Seiler, Christian; Hogan, S. D.; Merkt, F.

doi:10.2533/chimia.2012.208

Cited by 11 publications

(15 citation statements)

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“…To obtain experimental information on the evolution of an initial population of Rydberg atoms and molecules selectively prepared in Rydberg-Stark states, we have also measured the decay of the population of trapped Rydberg atoms and molecules for several hundreds of microseconds [34,[36][37][38]. These measurements are complementary to recent all-optical measurements of the lifetimes of selected nl Rydberg states following excitation of ultracold atoms in MOT, which reveal the decay of the initially prepared Rydberg states of Rb with principal quantum numbers in the range 30-40 by fluorescence, blackbody-radiation-induced and collisional processes [31] and to earlier studies of the influence of blackbody radiation, in particular ionization, on the lifetimes and other properties of Rydberg states of atoms (see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Seiler¹,

Agner²,

Pillet³

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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Supersonic beams of hydrogen atoms, prepared selectively in Rydberg-Stark states of principal quantum number n in the range between 25 and 35, have been deflected by 90 ○ , decelerated and loaded into off-axis electric traps at initial densities of ≈ 10 6 atoms/cm −3 and translational temperatures of 150 mK. The ability to confine the atoms spatially was exploited to study their decay by radiative and collisional processes. The evolution of the population of trapped atoms was measured for several milliseconds in dependence of the principal quantum number of the initially prepared states, the initial Rydberg-atom density in the trap, and the temperature of the environment of the trap, which could be varied between 7.5 K and 300 K using a cryorefrigerator. At room temperature, the population of trapped Rydberg atoms was found to decay faster than expected on the basis of their natural lifetimes, primarily because of absorption and emission stimulated by the thermal radiation field. At the lowest temperatures investigated experimentally, the decay was found to be multiexponential, with an initial rate scaling as n −4 and corresponding closely to the natural lifetimes of the initially prepared Rydberg-Stark states. The decay rate was found to continually decrease over time and to reach an almost n-independent rate of more than (1 ms) −1 after 3 ms. To analyze the experimentally observed decay of the populations of trapped atoms, numerical simulations were performed which included all radiative processes, i.e., spontaneous emission as well as absorption and emission stimulated by the thermal radiation. These simulations, however, systematically underestimated the population of trapped atoms observed after several milliseconds by almost two orders of magnitude, although they reliably predicted the decay rates of the remaining atoms in the trap. The calculations revealed that the atoms that remain in the trap for the longest times have larger absolute values of the magnetic quantum number m than the optically prepared RydbergStark states, and this observation led to the conclusion that a much more efficient mechanism than a purely radiative one must exist to induce transitions to Rydberg-Stark states of higher m values. While searching for such a mechanism, we discovered that resonant dipole-dipole collisions between Rydberg atoms in the trap represent an extremely efficient way of inducing transitions to states of higher m values. The efficiency of the mechanism is a consequence of the almost perfectly linear nature of the Stark effect at the moderate field strengths used to trap the atoms, which permits cascades of transitions between entire networks of near-degenerate Rydberg-atom-pair states. To include such cascades of resonant dipole-dipole transitions in the numerical simulations, we have generalized the two-state Förster-type collision model used to describe resonant collisions in ultracold Rydberg gases to a multi-state situation. It is only when considering the combined effects of collisional and radiative pr...

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Section: Introductionmentioning

confidence: 99%

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Seiler¹,

Agner²,

Pillet³

et al. 2016

J. Phys. B: At. Mol. Opt. Phys.

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“…The process was commissioned at the Joshkar-Ola plant without interrupting the running production of ascorbic acid, and its parameters are given in Table 1. Here are also given the parameters of the "low-current densities" technology, offered at Hoffmann La Roche [14,15]: reduced productivity is compensated in this case using special Swiss-roll cell with large surface area. This cell, developed by Robertson et al [16,17], is comprised of two bands (anode and cathode) of Ni foil with a~1 mm thick isolating plastic net, rolled into a cylindrical StS steel container; in a series, several such cells are used [14,15].…”

Section: Resultsmentioning

confidence: 99%

“…3 Electrochemical production of DAG, the dotted line shows a module unit: 1 electrolyzer, 2 cooler, 3 phase separator, 4 centrifugal pump, the first and the last modules are showed; 5 inlet reservoir; 6 dosing pump; 7 setting centrifuge; 8 separator. Lines a, b, c, and d correspond to the input of the initial solution DAS, the output of the solution DAG, exit the waste fine solid particles and solid product, basically Ni(OH) 2 , respectively (details in the text) [14,15] c The process was stopped in 1994 due to the cessation of production of vitamin C at the Joshkar-Ola plant was returned into the process after the regeneration, line d; nickel sulfate was added to the solution as appropriate. The monitoring of the process was carried out by measuring the steady-state concentrations DAG (see "Experimental").…”

Section: Resultsmentioning

confidence: 99%

“…Otherwise, current efficiencies are not high enough: typically 30-50 %, even when using modern anode materials, such as Ni foams [11][12][13] with the special cell [12,13]. The decrease of the current density leads to the corresponding reduction in productivity; the necessary capacity is provided then by increasing the anode surface area [14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Improving the catalytic activity of nickel-containing anodes for the oxidation of alcohols

Mairanovsky¹,

Gitlin

Rosanov³

2012

J Solid State Electrochem

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Looking for ways to improve the catalytic activity of a Ni anode during the oxidation of alcohols in basic medium, we tested the action of amino compounds as Nicomplexing agents. We have discovered a significant increase in the effective rate of oxidation of alcohols to the corresponding carboxylic acids in the presence of amino compounds. The activating effect of amino compounds (AEAC) became the basis for the industrial method to produce the carboxylic acid diaceton-2-keto-L-gulonic acid (DAG), an intermediate in the synthesis of vitamin C. The DAG electrosynthesis at stainless steel (StS) anodes with a capacity of 1,500 t/year/production line was developed. The application of the electrochemical method allowed drastically reducing the wastes and resulted in significant economy effects. Operation during 10 years showed good anode corrosion resistance, stability, and safety of the process. There are other possible AEAC applications, in particular, for increasing the sensitivity of ROH sensors. The possibility of using the AEAC effect for improving the efficiency of direct alcohol fuel cells (DAFC) with Ni-containing systems is also discussed.

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“…Therefore, they do not directly lead to a loss of guided atoms but instead to an increase in the range of populated states with time, and a subsequent increase in the sample's translational temperature. It will be important in future experiments to cool the apparatus to low temperatures to minimize these effects [12,32], to permit precise collision or spectroscopic studies to be performed with guided samples in selected Rydberg-Stark states.…”

Section: Discussionmentioning

confidence: 99%

High-field-seeking Rydberg atoms orbiting a charged wire

Hogan

2014

Phys. Rev. A

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Pulsed supersonic beams of helium atoms in the high-field-seeking 52p Rydberg state have been guided while following helical trajectories in the electrostatic field of a charged wire suspended along the axis of a grounded cylindrical metallic tube. The operation of this electrostatic wire guide for samples in high-field-seeking Rydberg-Stark states has been investigated with dc and pulsed electric potentials applied to the wire while the guided atoms were detected by pulsed electric-field ionization. The acceptance of the guide has been determined through numerical particle trajectory simulations.

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Dynamical Processes in Rydberg-Stark Deceleration and Trapping of Atoms and Molecules

Cited by 11 publications

References 20 publications

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Radiative and collisional processes in translationally cold samples of hydrogen Rydberg atoms studied in an electrostatic trap

Improving the catalytic activity of nickel-containing anodes for the oxidation of alcohols

High-field-seeking Rydberg atoms orbiting a charged wire

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