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Rayment MH, Hogan SD. Electrostatic Trapping of N_{2} Molecules in High Rydberg States. PHYSICAL REVIEW LETTERS 2024; 132:113201. [PMID: 38563928 DOI: 10.1103/physrevlett.132.113201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 02/12/2024] [Indexed: 04/04/2024]
Abstract
N_{2} molecules traveling in pulsed supersonic beams have been excited from their X ^{1}Σ_{g}^{+} ground electronic state to long-lived Rydberg states with principal quantum numbers between 39 and 48 using a resonance-enhanced two-color three-photon excitation scheme. The Rydberg states populated had static electric dipole moments exceeding 5000 D which allowed deceleration of the molecules to rest in the laboratory-fixed frame of reference and three-dimensional trapping using inhomogeneous electric fields. The trapped molecules were confined for up to 10 ms, with effective trap decay time constants increasing with principal quantum number, and ranging from 450 to 700 μs. These observations, and comparison with the results of similar measurements with He atoms, indicate that the decay dynamics of the trapped Rydberg N_{2} molecules are dominated by spontaneous emission and do not exhibit significant contributions from effects of intramolecular interactions that lead to non-radiative decay.
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Affiliation(s)
- M H Rayment
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S D Hogan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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2
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Zhelyazkova V, Martins FBV, Schilling S, Merkt F. Reaction of an Ion and a Free Radical near 0 K: He + + NO → He + N + + O. J Phys Chem A 2023; 127:1458-1468. [PMID: 36752385 PMCID: PMC9940198 DOI: 10.1021/acs.jpca.2c08221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The reactions between ions and free radicals are among the fastest chemical reactions. They are predicted to proceed with large rates, even near 0 K, but so far, this prediction has not been verified experimentally. We report on measurements of the rate coefficient of the reaction between the ion He+ and the free radical NO at collision energies in the range between 0 and ∼ kB·10 K. To avoid heating of the ions by stray electric fields, the reaction is observed within the large orbit of a Rydberg electron of principal quantum number n ≥ 30, which shields the ion from external electric fields without affecting the reaction. Low collision energies are reached by merging a supersonic beam of He Rydberg atoms with a supersonic beam of NO molecules and adjusting their relative velocity using a chip-based Rydberg-Stark decelerator and deflector. We observe a strong enhancement of the reaction rate at collision energies below ∼kB·2 K. This enhancement is interpreted on the basis of adiabatic-channel capture-rate calculations as arising from the near-degenerate rotational levels of opposite parity resulting from the Λ-doubling in the X 2Π1/2 ground state of NO. With these new results, we examine the reliability of broadly used approximate analytic expressions for the thermal rate constants of ion-molecule reactions at low temperatures.
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3
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Höveler K, Deiglmayr J, Merkt F. Deviation of the rate of the reaction from Langevin behaviour below 1 K, branching ratios for the and product channels, and product-kinetic-energy distributions. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1954708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | - Johannes Deiglmayr
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
- Department of Physics, University of Leipzig, Leipzig, Germany
| | - Frédéric Merkt
- Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
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Höveler K, Deiglmayr J, Agner JA, Schmutz H, Merkt F. The H 2+ + HD reaction at low collision energies: H 3+/H 2D + branching ratio and product-kinetic-energy distributions. Phys Chem Chem Phys 2021; 23:2676-2685. [PMID: 33480928 DOI: 10.1039/d0cp06107g] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fully state-selected reactions between H2+ molecules in the X+ 2Σg+(v+ = 0, N+ = 0) state and HD molecules in the X 1Σg+(v = 0, J = 0) state forming H3+ + D and H2D+ + H have been studied at collision energies Ecoll between 0 and kB·30 K with a resolution of about 75 mK at the lowest energies. H2 molecules in a supersonic beam were prepared in Rydberg-Stark states with principal quantum number n = 27 and merged with a supersonic beam of ground-state HD molecules using a curved surface-electrode Rydberg-Stark decelerator and deflector. The reaction between H2+ and HD was studied within the orbit of the Rydberg electron to avoid heating of the ions by stray electric fields. The reaction was observed for well-defined and adjustable time intervals, called reaction-observation windows, between two electric-field pulses. The first pulse swept all ions away from the reaction volume and its falling edge defined the beginning of the reaction-observation window. The second pulse extracted the product ions toward a charged-particle detector located at the end of a time-of-flight tube and its rising edge defined the end of the reaction-observation window. Monitoring and analysing the time-of-flight distributions of the H3+ and H2D+ products in dependence of the duration of the reaction-observation window enabled us to obtain information on the kinetic-energy distribution of the product ions and determine branching ratios of the H3+ + D and H2D+ + H reaction channels. The mean product-kinetic-energy release is 0.46(5) eV, representing 27(3)% of the available energy, and the H3+ + D product branching ratio is 0.225(20). The relative reaction rates correspond closely to Langevin capture rates down to the lowest energies probed experimentally (≈kB·50 mK).
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Affiliation(s)
- Katharina Höveler
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Johannes Deiglmayr
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Josef A Agner
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Hansjürg Schmutz
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Frédéric Merkt
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
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Zhelyazkova V, Martins FBV, Agner JA, Schmutz H, Merkt F. Ion-Molecule Reactions below 1 K: Strong Enhancement of the Reaction Rate of the Ion-Dipole Reaction He^{+}+CH_{3}F. PHYSICAL REVIEW LETTERS 2020; 125:263401. [PMID: 33449728 DOI: 10.1103/physrevlett.125.263401] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/14/2020] [Accepted: 11/04/2020] [Indexed: 06/12/2023]
Abstract
The reaction between He^{+} and CH_{3}F forming predominantly CH_{2}^{+} and CHF^{+} has been studied at collision energies E_{coll} between 0 and k_{B}·10 K in a merged-beam apparatus. To avoid heating of the ions by stray electric fields, the reaction was observed within the orbit of a highly excited Rydberg electron. Supersonic beams of CH_{3}F and He(n) Rydberg atoms with principal quantum number n=30 and 35 were merged and their relative velocity tuned using a Rydberg-Stark decelerator and deflector, allowing an energy resolution of 150 mK. A strong enhancement of the reaction rate was observed below E_{coll}/k_{B}=1 K. The experimental results are interpreted with an adiabatic capture model that accounts for the state-dependent orientation of the polar CH_{3}F molecules by the Stark effect as they approach the He^{+} ion. The enhancement of the reaction rate at low collision energies is primarily attributed to para-CH_{3}F molecules in the J=1, KM=1 high-field-seeking states, which represent about 8% of the population at the 6 K rotational temperature of the supersonic beam.
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Affiliation(s)
| | | | - Josef A Agner
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Hansjürg Schmutz
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Frédéric Merkt
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
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Jansen P, Merkt F. Manipulating beams of paramagnetic atoms and molecules using inhomogeneous magnetic fields. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 120-121:118-148. [PMID: 33198967 DOI: 10.1016/j.pnmrs.2020.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/07/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
We review methods to manipulate the motion of pulsed supersonic atomic and molecular beams using time-independent and -dependent inhomogeneous magnetic fields. In addition, we discuss current and possible future applications and research directions.
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Affiliation(s)
- Paul Jansen
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Frédéric Merkt
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
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7
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Zhelyazkova V, Žeško* M, Schmutz H, Agner JA, Merkt F. Fluorescence-lifetime-limited trapping of Rydberg helium atoms on a chip. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1600060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- V. Zhelyazkova
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - M. Žeško*
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - H. Schmutz
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - J. A. Agner
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
| | - F. Merkt
- Physical Chemistry Laboratory, ETH Zürich, Zürich, Switzerland
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Jones ACL, Moxom J, Rutbeck-Goldman HJ, Osorno KA, Cecchini GG, Fuentes-Garcia M, Greaves RG, Adams DJ, Tom HWK, Mills AP, Leventhal M. Focusing of a Rydberg Positronium Beam with an Ellipsoidal Electrostatic Mirror. PHYSICAL REVIEW LETTERS 2017; 119:053201. [PMID: 28949762 DOI: 10.1103/physrevlett.119.053201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Indexed: 06/07/2023]
Abstract
Slow atoms in Rydberg states can exhibit specular reflection from a cylindrical surface upon which an azimuthally periodic potential is imposed. We have constructed a concave mirror of this type, in the shape of a truncated oblate ellipsoid of revolution, which has a focal length of (1.50±0.01) m measured optically. When placed near the center of a long vacuum pipe, this structure brings a beam of n=32 positronium (Ps) atoms to a focus on a position sensitive detector at a distance of (6.03±0.03) m from the Ps source. The intensity at the focus implies an overall reflection efficiency of ∼30%. The focal spot diameter (32±1) mm full width at half maximum is independent of the atoms' flight times from 20 to 60 μs, thus indicating that the mirror is achromatic to a good approximation. Mirrors based on this principle would be of use in a variety of experiments, allowing for improved collection efficiency and tailored transport or imaging of beams of slow Rydberg atoms and molecules.
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Affiliation(s)
- A C L Jones
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - J Moxom
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - H J Rutbeck-Goldman
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - K A Osorno
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - G G Cecchini
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - M Fuentes-Garcia
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - R G Greaves
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - D J Adams
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - H W K Tom
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - A P Mills
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - M Leventhal
- Department of Astronomy University of Maryland, College Park, Maryland 20742, USA
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9
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Kienitz JS, Długołęcki K, Trippel S, Küpper J. Improved spatial separation of neutral molecules. J Chem Phys 2017; 147:024304. [DOI: 10.1063/1.4991479] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jens S. Kienitz
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Center for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Karol Długołęcki
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Sebastian Trippel
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Center for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jochen Küpper
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Center for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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10
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Hogan SD. Rydberg-Stark deceleration of atoms and molecules. EPJ TECHNIQUES AND INSTRUMENTATION 2016; 3:2. [PMID: 32355605 PMCID: PMC7175735 DOI: 10.1140/epjti/s40485-015-0028-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/27/2015] [Indexed: 06/06/2023]
Abstract
The large electric dipole moments associated with highly excited Rydberg states of atoms and molecules make gas-phase samples in these states very well suited to deceleration and trapping using inhomogeneous electric fields. The methods of Rydberg-Stark deceleration with which this can be achieved are reviewed here. Using these techniques, the longitudinal motion of beams of atoms and molecules moving at speeds as high as 2500 m/s have been manipulated, with changes in kinetic energy of up to |Δ E kin|=1.3×10-20 J (|Δ E kin|/e=80 meV or |Δ E kin|/h c=650 cm -1) achieved, while decelerated and trapped samples with number densities of 106- 107 cm -3 and translational temperatures of ∼150 mK have been prepared. Applications of these samples in areas of research at the interface between physics and physical chemistry are discussed.
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Affiliation(s)
- Stephen D. Hogan
- Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT UK
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11
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Bichsel BJ, Alexander J, Dahal P, Morrison MA, Shafer-Ray NE, Abraham ERI. Creation of cold nitric oxide by extraction of the cold fraction of a thermal distribution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:103102. [PMID: 26520935 DOI: 10.1063/1.4931756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We describe a device using the Stark effect to extract the cold fraction of nitric oxide molecules from a warmer thermal distribution. Room temperature NO is cryogenically cooled to 72-82 K and injected into a straight, hexapole guide that uses the Stark effect. By blocking line-of-sight trajectories from the input to the output, primarily the slowest molecules are guided around the obstruction and are transferred into a new chamber. We measure the temperature distribution using a field-stabilized Rydberg time-of-flight technique. A superposition of molecular Rydberg states is excited, sufficiently increasing the lifetime of the excited state for a time-of-flight measurement for cold molecular samples. We produce a continuous source of nitric oxide with temperatures ranging from 7 to 20 K in the lowest ro-vibrational state. The output temperature is controlled by the initial temperature distribution and the guide voltage.
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Affiliation(s)
- Bryan J Bichsel
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Jason Alexander
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Parshuram Dahal
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Michael A Morrison
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA
| | - Neil E Shafer-Ray
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA
| | - E R I Abraham
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, Oklahoma 73019, USA
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12
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Abstract
The field of cold molecules has become an important source of new insight in fundamental chemistry and molecular physics. High-resolution spectroscopy benefits from translationally and internally cold molecules by increased interaction times and reduced spectral congestion. Completely new effects in scattering dynamics become accessible with cold and controlled molecules. Many of these experiments use molecular beams as a starting point for the generation of molecular samples. This review gives an overview of methods to produce beams of cold molecules, starting from supersonic expansions or effusive sources, and provides examples of applications in spectroscopy and molecular dynamics studies.
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Affiliation(s)
- Justin Jankunas
- Institute for Chemistry and Chemical Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Andreas Osterwalder
- Institute for Chemistry and Chemical Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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13
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Dulitz K, Motsch M, Vanhaecke N, Softley TP. Getting a grip on the transverse motion in a Zeeman decelerator. J Chem Phys 2014; 140:104201. [PMID: 24628161 DOI: 10.1063/1.4866906] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Zeeman deceleration is an experimental technique in which inhomogeneous, time-dependent magnetic fields generated inside an array of solenoid coils are used to manipulate the velocity of a supersonic beam. A 12-stage Zeeman decelerator has been built and characterized using hydrogen atoms as a test system. The instrument has several original features including the possibility to replace each deceleration coil individually. In this article, we give a detailed description of the experimental setup, and illustrate its performance. We demonstrate that the overall acceptance in a Zeeman decelerator can be significantly increased with only minor changes to the setup itself. This is achieved by applying a rather low, anti-parallel magnetic field in one of the solenoid coils that forms a temporally varying quadrupole field, and improves particle confinement in the transverse direction. The results are reproduced by three-dimensional numerical particle trajectory simulations thus allowing for a rigorous analysis of the experimental data. The findings suggest the use of a modified coil configuration to improve transverse focusing during the deceleration process.
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Affiliation(s)
- Katrin Dulitz
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Michael Motsch
- Laboratorium für Physikalische Chemie, ETH Zürich, 8093 Zürich, Switzerland
| | - Nicolas Vanhaecke
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany and Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, 91405 Orsay, France
| | - Timothy P Softley
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
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Wiederkehr A, Schmutz H, Motsch M, Merkt F. Velocity-tunable slow beams of cold O2in a single spin-rovibronic state with full angular-momentum orientation by multistage Zeeman deceleration. Mol Phys 2012. [DOI: 10.1080/00268976.2012.681312] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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15
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van de Meerakker SYT, Bethlem HL, Vanhaecke N, Meijer G. Manipulation and Control of Molecular Beams. Chem Rev 2012; 112:4828-78. [DOI: 10.1021/cr200349r] [Citation(s) in RCA: 247] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Hendrick L. Bethlem
- Institute for Lasers, Life and
Biophotonics, VU University Amsterdam,
De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Nicolas Vanhaecke
- Laboratoire Aimé Cotton, CNRS, Bâtiment 505, Université Paris-Sud,
91405 Orsay, France
| | - Gerard Meijer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin,
Germany
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Hogan SD, Allmendinger P, Sassmannshausen H, Schmutz H, Merkt F. Surface-electrode Rydberg-Stark decelerator. PHYSICAL REVIEW LETTERS 2012; 108:063008. [PMID: 22401069 DOI: 10.1103/physrevlett.108.063008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Indexed: 05/31/2023]
Abstract
Hydrogen atoms in Rydberg states with principal quantum numbers between 23 and 70 have been accelerated, decelerated, and electrostatically trapped using a surface-electrode Rydberg-Stark decelerator. By applying a set of oscillating electrical potentials to a two-dimensional array of electrodes on a printed circuit board (PCB), a continuously moving, three-dimensional electric trap with a predefined velocity and acceleration is generated. From an initial longitudinal velocity of 760 m/s, final velocities of the Rydberg atoms ranging from 1200 m/s to zero velocity in the laboratory-fixed frame of reference were achieved. Accelerated or decelerated atoms were detected directly by pulsed electric-field ionization. Atoms trapped at zero mean velocity above the PCB were reaccelerated off the PCB before field ionization.
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Affiliation(s)
- S D Hogan
- Laboratorium für Physikalische Chemie, ETH Zürich, Zürich, Switzerland
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Seiler C, Hogan SD, Schmutz H, Agner JA, Merkt F. Collisional and radiative processes in adiabatic deceleration, deflection, and off-axis trapping of a Rydberg atom beam. PHYSICAL REVIEW LETTERS 2011; 106:073003. [PMID: 21405512 DOI: 10.1103/physrevlett.106.073003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Indexed: 05/30/2023]
Abstract
A supersonic beam of Rydberg hydrogen atoms has been adiabatically deflected by 90°, decelerated to zero velocity in less than 25 μs, and loaded into an electric trap. The deflection has allowed the suppression of collisions with atoms in the trailing part of the gas pulse. The processes leading to trap losses, i.e., fluorescence to the ground state, and transitions and ionization induced by blackbody radiation have been monitored over several milliseconds and quantitatively analyzed.
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Affiliation(s)
- Ch Seiler
- Laboratorium für Physikalische Chemie, ETH Zürich, Switzerland
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Affiliation(s)
- Ch Seiler
- ETH Zurich, Laboratory of Physical Chemistry, Wolfgang Pauli-Str. 10, Zurich, Switzerland
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19
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Hogan SD, Motsch M, Merkt F. Deceleration of supersonic beams using inhomogeneous electric and magnetic fields. Phys Chem Chem Phys 2011; 13:18705-23. [DOI: 10.1039/c1cp21733j] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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McCormack EA, Ford MS, Softley TP. Level crossings in the ionization of H(2) Rydberg molecules at a metal surface. J Phys Chem A 2010; 114:11175-88. [PMID: 20593817 DOI: 10.1021/jp102817c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The ionization of H(2) Rydberg states at a metal surface is investigated using a molecular beam incident at grazing incidence on a gold surface. The H(2) molecules, excited by stepwise two-color laser excitation, are selected in each of the accessible Stark eigenstates of the N(+) = 2, n = 17 Rydberg manifold in turn and the ionization at the surface is characterized by applying a field to extract the ions formed. Profiles of extracted ion signal versus applied field show resonances that can be simulated by assuming an enhancement of surface ionization at fields corresponding to energy-level crossings between the populated N(+) = 2 manifold and the near-degenerate N(+) = 0 Stark manifolds. It is concluded that the slow (microsecond time scale) rotation-electronic energy transfer to N(+) = 0 states occurring at these crossings takes place in the time interval following application of the field ramp when the molecule is still distant from, and unperturbed by, the surface. However, the energy levels are strongly perturbed by image-dipole interactions as the molecule approaches close to the surface, leading to additional energy-level crossings. Adiabatic behavior at such crossings affects the intensity of the observed resonances in the surface ionization signal but not their field positions. Resonances are also observed in the surface ionization profiles at fields above the field-ionization threshold; some of these show asymmetric "Fano-type" line shapes due to quantum interference in the nonradiative coupling to degenerate bound and continuum states.
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Affiliation(s)
- E A McCormack
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, United Kingdom
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Hogan SD, Seiler C, Merkt F. Rydberg-state-enabled deceleration and trapping of cold molecules. PHYSICAL REVIEW LETTERS 2009; 103:123001. [PMID: 19792428 DOI: 10.1103/physrevlett.103.123001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Indexed: 05/28/2023]
Abstract
Hydrogen molecules in selected core-nonpenetrating Rydberg-Stark states have been decelerated from a mean initial velocity of 500 m/s to zero velocity in the laboratory frame and loaded into a three-dimensional electrostatic trap. Trapping times, measured by pulsed electric field ionization of the trapped molecules, are found to be limited by collisional processes. As Rydberg states can be deexcited to the absolute ground state, the method can be applied to generate cold samples of a wide range of species.
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Affiliation(s)
- S D Hogan
- Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093, Switzerland
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23
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Hogan SD, Wiederkehr AW, Schmutz H, Merkt F. Magnetic trapping of hydrogen after multistage Zeeman deceleration. PHYSICAL REVIEW LETTERS 2008; 101:143001. [PMID: 18851525 DOI: 10.1103/physrevlett.101.143001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Indexed: 05/26/2023]
Abstract
We report the first experimental realization of magnetic trapping of a sample of cold radicals following multistage Zeeman deceleration of a pulsed supersonic beam. H atoms seeded in a supersonic expansion of Kr have been decelerated from an initial velocity of 520 m/s to 100 m/s in a 12-stage Zeeman decelerator and loaded into a magnetic quadrupole trap by rapidly switching the fields of the trap solenoids.
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Affiliation(s)
- S D Hogan
- Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093, Switzerland
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24
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Clarson B, Procter S, Goodgame A, Softley T. The Stark effect in the predissociating Rydberg states of NO. Mol Phys 2008. [DOI: 10.1080/00268970802298753] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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25
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Quack M, Stohner J, Willeke M. High-Resolution Spectroscopic Studies and Theory of Parity Violation in Chiral Molecules. Annu Rev Phys Chem 2008; 59:741-69. [DOI: 10.1146/annurev.physchem.58.032806.104511] [Citation(s) in RCA: 198] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We review the high-resolution spectroscopic approach toward the study of intramolecular dynamics, emphasizing molecular parity violation. Theoretical work in the past decade has shown that parity-violating potentials in chiral molecules are much larger (typically one to two orders of magnitude) than anticipated on the basis of older theories. This makes experimental approaches toward small molecular parity-violating effects promising. The concepts and results of intramolecular dynamics derived from spectroscopy are analyzed as a sequence of symmetry breakings. We summarize the concepts of symmetry breakings (de facto and de lege) in view of parity violation in chiral molecules. The experimental schemes and the current status of spectroscopic experiments on molecular parity violation are established. We discuss the promises of detecting and accurately measuring parity-violating energy differences Δpv E on the order of 10−11 J mol−1 (approximately 100 aeV) in enantiomers of chiral molecules with regard to their contribution to fundamental physics in the framework of the standard model of particle physics and more speculative future fundamental symmetry tests such as for the combined charge conjugation, parity, and time-reversal (CPT) symmetry violation.
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Affiliation(s)
- Martin Quack
- ETH Zürich Laboratorium für Physikalische Chemie, CH-8093 Zürich, Switzerland
| | - Jürgen Stohner
- Permanent address: Institute of Chemistry and Biology, Zürich University of Applied Sciences, CH-8400 Winterthur, Switzerland
| | - Martin Willeke
- Permanent address: Departement für Materialwissenschaften, ETH Zürich, 8093 Zürich, Switzerland
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26
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Hogan SD, Merkt F. Demonstration of three-dimensional electrostatic trapping of state-selected Rydberg atoms. PHYSICAL REVIEW LETTERS 2008; 100:043001. [PMID: 18352264 DOI: 10.1103/physrevlett.100.043001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Indexed: 05/26/2023]
Abstract
A three-dimensional trap for Rydberg atoms in selected Stark states has been realized experimentally. H atoms seeded in a supersonic expansion of Ar are excited to the low-field seeking n=30, k=25, |m|=0, 2 Rydberg-Stark states, decelerated from a mean initial velocity of 665 m/s to zero velocity in the laboratory frame and loaded into a three-dimensional electrostatic trap. The motion of the cold Rydberg atom cloud in the trap and the decay of the trapped atoms have been studied by pulsed electric field ionization and imaging techniques.
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Affiliation(s)
- S D Hogan
- Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093, Switzerland
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27
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Paul THA, Cruse HA, Wörner HJ, Merkt F. Structure and dynamics of the high gerade Rydberg states of D2 in the vicinity of the adiabatic ionization threshold. Mol Phys 2007. [DOI: 10.1080/00268970601146898] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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28
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Lloyd GR, Procter SR, McCormack EA, Softley TP. Ionization of H2 Rydberg molecules at a metal surface. J Chem Phys 2007; 126:184702. [PMID: 17508819 DOI: 10.1063/1.2730792] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The ionization of a beam of H2 Rydberg molecules in collision with a metal surface (evaporated Au or Al) is studied. The Rydberg states are excited in an ultraviolet-vacuum ultraviolet double-resonant process and are state selected with a core rotational quantum number N+=0 or 2 and principal quantum numbers n=17-22 (N+=2) or n=41-45 (N+=0). It is found that the N+=0 states behave in a very similar manner to previous studies with atomic xenon Rydberg states, the distance of ionization from the surface scaling with n2. The N+=2 states, however, undergo a process of surface-induced rotational autoionization in which the core rotational energy transfers to the Rydberg electron. In this case the ionization distance scales approximately with nu0(2), the effective principal quantum number with respect to the adiabatic threshold. This process illustrates the close similarity between field ionization in the gas phase and the surface ionization process which is induced by the field due to image charges in the metal surface. The surface ionization rate is enhanced at certain specific values of the field, which is applied in the time interval between excitation and surface interaction. It is proposed here that these fields correspond to level crossings between the N+=0 and N+=2 Stark manifolds. The population of individual states of the N+=2, n=18 Stark manifold in the presence of a field shows that the surface-induced rotational autoionization is more facile for the blueshifted states, whose wave function is oriented away from the surface, than for the redshifted states. The observed processes appear to show little dependence on the chemical nature of the metallic surface, but a significant change occurs when the surface roughness becomes comparable to the Rydberg orbit dimensions.
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Affiliation(s)
- G R Lloyd
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
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29
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Softley TP. Applications of molecular Rydberg states in chemical dynamics and spectroscopy. INT REV PHYS CHEM 2007. [DOI: 10.1080/01442350310001652940] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- T. P. Softley
- a Department of Chemistry , Chemistry Research Laboratory, University of Oxford , Mansfield Rd, Oxford OX1 3TA, UK
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30
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Vliegen E, Merkt F. Normal-incidence electrostatic Rydberg atom mirror. PHYSICAL REVIEW LETTERS 2006; 97:033002. [PMID: 16907498 DOI: 10.1103/physrevlett.97.033002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Indexed: 05/11/2023]
Abstract
A Rydberg atom mirror has been designed and its operational principle tested experimentally. A supersonic expansion containing H atoms moving with a velocity of 720 m/s initially propagates toward a quadrupolar electrostatic mirror. The H atoms are then photoexcited to n=27 Rydberg states with a positive Stark shift and move in a rapidly increasing electric field. The H atom beam is stopped in 4.8 micros, only 1.9 mm away from the photoexcitation spot, and is then reflected back. The reflection process is monitored by pulsed field ionization and imaging.
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Affiliation(s)
- E Vliegen
- Laboratorium für Physikalische Chemie, ETH Zürich CH-8093, Zurich, Switzerland
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31
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Lloyd GR, Procter SR, Softley TP. Ionization of hydrogen Rydberg molecules at a metal surface. PHYSICAL REVIEW LETTERS 2005; 95:133202. [PMID: 16197138 DOI: 10.1103/physrevlett.95.133202] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Indexed: 05/04/2023]
Abstract
The interaction of a beam of Rydberg molecules with a metal surface is investigated for the first time. Hydrogen molecules in a supersonic expansion are excited to Rydberg states with principal quantum number n, in the range 17-22 and are directed at a small angle onto a flat surface of either aluminum or gold. Detection of ions produced when Rydberg electrons tunnel into the metal surface provides information on the interaction between the Rydberg molecules and the surface potential. The experimental results suggest that, when close to the metal surface, the Rydberg molecules undergo a process of surface-induced rotational autoionization. It is found that the surface-ionization cross section shows strong resonances as a function of the applied electric field, which are independent of the metal studied.
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Affiliation(s)
- G R Lloyd
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, United Kingdom
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32
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Yamakita Y, Procter SR, Goodgame AL, Softley TP, Merkt F. Deflection and deceleration of hydrogen Rydberg molecules in inhomogeneous electric fields. J Chem Phys 2004; 121:1419-31. [PMID: 15260687 DOI: 10.1063/1.1763146] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hydrogen molecules are excited in a molecular beam to Rydberg states around n=17-18 and are exposed to the inhomogeneous electric field of an electric dipole. The large dipole moment produced in the selected Stark eigenstates leads to strong forces on the H2 molecules in the inhomogeneous electric field. The trajectories of the molecules are monitored using ion-imaging and time of flight measurements. With the dipole rods mounted parallel to the beam direction, the high-field-seeking and low-field-seeking Stark states are deflected towards and away from the dipole, respectively. The magnitude of the deflection is measured as a function of the parabolic quantum number k and of the duration of the applied field. It is also shown that a large deflection is observed when populating the (17d2)1 state at zero field and switching the dipole field on after a delay. With the dipole mounted perpendicular to the beam direction, the molecules are either accelerated or decelerated as they move towards the dipole. The Rydberg states are found to survive for over 100 micros after the dipole field is switched off before being ionized at the detector and the time of flight is measured. A greater percentage change in kinetic energy is achieved by initial seeding of the beam in helium or neon followed by inhomogeneous field deceleration/acceleration. Molecular dynamics trajectory simulations are presented highlighting the extent to which the trajectories can be predicted based on the known Stark map. The spectroscopy of the populated states is discussed in detail and it is established that the N+=2, J=1, MJ=0 states populated here have a special stability with respect to decay by predissociation.
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Affiliation(s)
- Y Yamakita
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, United Kingdom
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33
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Nguyen NA, Dey BK, Shapiro M, Brumer P. Coherent Control in Nanolithography: Rydberg Atoms. J Phys Chem A 2004. [DOI: 10.1021/jp040035b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nam A. Nguyen
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada
| | - Bijoy K. Dey
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada
| | - Moshe Shapiro
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada
| | - Paul Brumer
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada
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34
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Vliegen E, Wörner HJ, Softley TP, Merkt F. Nonhydrogenic effects in the deceleration of Rydberg atoms in inhomogeneous electric fields. PHYSICAL REVIEW LETTERS 2004; 92:033005. [PMID: 14753872 DOI: 10.1103/physrevlett.92.033005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Indexed: 05/24/2023]
Abstract
Argon atoms in Stark states at n approximately 25 have been decelerated and accelerated in inhomogeneous electric fields. The acceleration and deceleration behavior can be understood only by considering the adiabatic Landau-Zener dynamics that take place at the avoided crossings between the Stark states and the limited fluorescence lifetimes of approximately 10 micros.
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Affiliation(s)
- E Vliegen
- Laboratorium für Physikalische Chemie, ETH Zürich CH-8093, Switzerland
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