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Ahokas J, Semakin A, Järvinen J, Hanski O, Laptiyenko A, Dvornichenko V, Salonen K, Burkley Z, Crivelli P, Golovizin A, Nesvizhevsky V, Nez F, Yzombard P, Widmann E, Vasiliev S. A large octupole magnetic trap for research with atomic hydrogen. Rev Sci Instrum 2022; 93:023201. [PMID: 35232145 DOI: 10.1063/5.0070037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
We describe the design and performance of a large magnetic trap for storage and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K. Aiming at a large volume of the trap, we implemented the octupole configuration of linear currents (Ioffe bars) for the radial confinement, combined with two axial pinch coils and a 3 T solenoid for the cryogenic H dissociator. The octupole magnet consists of eight race-track segments, which are compressed toward each other with magnetic forces. This provides a mechanically stable and robust construction with a possibility of replacement or repair of each segment. A maximum trap depth of 0.54 K (0.8 T) was reached, corresponding to an effective volume of 0.5 l for hydrogen gas at 50 mK. This is an order of magnitude larger than ever used for trapping atoms.
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Affiliation(s)
- J Ahokas
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - A Semakin
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Järvinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - O Hanski
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - A Laptiyenko
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - V Dvornichenko
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - K Salonen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - Z Burkley
- ETH Zurich, Institute for Particle Physics and Astrophysics, 8093 Zurich, Switzerland
| | - P Crivelli
- ETH Zurich, Institute for Particle Physics and Astrophysics, 8093 Zurich, Switzerland
| | - A Golovizin
- P.N. Lebedev Physical Institute, 53 Leninsky pr., Moscow, Ru-119991, Russia
| | - V Nesvizhevsky
- Institut Max von Laue-Paul Langevin, 71 Avenue des Martyrs, Grenoble F-38042, France
| | - F Nez
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Université, Collège de France, 75252 Paris, France
| | - P Yzombard
- Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Université, Collège de France, 75252 Paris, France
| | - E Widmann
- Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Kegelgasse 27, A-1030 Wien, Austria
| | - S Vasiliev
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
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Sheludiakov S, Lee DM, Khmelenko VV, Järvinen J, Ahokas J, Vasiliev S. Purely Spatial Quantum Diffusion of H Atoms in Solid H_{2} at Temperatures below 1 K. Phys Rev Lett 2021; 126:195301. [PMID: 34047604 DOI: 10.1103/physrevlett.126.195301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 04/14/2021] [Indexed: 06/12/2023]
Abstract
We report on a direct measurement of the quantum diffusion of H atoms in solid molecular hydrogen films at T=0.7 K. We obtained a rate of pure spatial diffusion of H atoms in the H_{2} films, D^{d}=5(2)×10^{-17} cm^{2} s^{-1}, which was 2 orders of magnitude faster than that obtained from H atom recombination, the quantity used in all previous work to characterize the mobility of H atoms in solid H_{2}. We also observed that the H-atom diffusion was significantly enhanced by injection of phonons. Our results provide the first measurement of the pure spatial diffusion rate for H atoms in solid H_{2}, the only solid state system beside ^{3}He-^{4}He mixtures, where atomic diffusion does not vanish even at temperatures below 1 K.
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Affiliation(s)
- S Sheludiakov
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - V V Khmelenko
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - J Järvinen
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Ahokas
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Vasiliev
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
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3
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Sheludiakov S, Lee DM, Khmelenko VV, Järvinen J, Ahokas J, Vasiliev S. Experimental cell with a Fabry-Pérot resonator tuned in situ for magnetic resonance studies of matrix-isolated radicals at temperatures below 1 K. Rev Sci Instrum 2020; 91:063901. [PMID: 32611001 DOI: 10.1063/5.0012178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 05/26/2020] [Indexed: 06/11/2023]
Abstract
We describe the design and construction of an experimental cell for the study of free radicals in macroscopically thick films of solidified molecular and rare gases by 128 GHz Electron Spin Resonance (ESR) at temperatures below 1 K. The ESR resonator has an open Fabry-Pérot design, and its frequency can be tuned in situ by adjusting the spacing between the mirrors. The tuning mechanism consists of a piezo positioner and a stainless-steel edge-welded bellows, which can change the resonator frequency by at least 6 GHz. The films of solidified gases can be deposited either directly from a room temperature reservoir or by recondensing from a specially arranged chamber. The free radicals can be created in the solid films by dissociating matrix species by running an rf discharge in a helium vapor. We suggest that such a sample cell design can also be used for a broad range of low-temperature ESR experiments where sample cooling needs to be enhanced by the presence of superfluid helium.
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Affiliation(s)
- S Sheludiakov
- Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - V V Khmelenko
- Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - J Järvinen
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Ahokas
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Vasiliev
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
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Järvinen J, Zvezdov D, Ahokas J, Sheludiakov S, Lehtonen L, Vasiliev S, Vlasenko L, Ishikawa Y, Fujii Y. Dynamic nuclear polarization and ESR hole burning in As doped silicon. Phys Chem Chem Phys 2020; 22:10227-10237. [PMID: 32352086 DOI: 10.1039/c9cp06859g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an experimental study of the Dynamic Nuclear Polarization (DNP) of 29Si nuclei in silicon crystals of natural abundance doped with As in the temperature range 0.1-1 K and in a strong magnetic field of 4.6 T. This ensures a very high degree of electron spin polarization, extremely slow nuclear relaxation and optimal conditions for realization of Overhauser and resolved solid effects. We found that the solid effect DNP leads to the appearance of a pattern of holes and peaks in the ESR line, separated by the super-hyperfine interaction between the donor electron and 29Si nuclei closest to the donor. On the contrary, the Overhauser effect DNP mainly affects the remote 29Si nuclei having the weakest interaction with the donor electron. This leads to the appearance of a very narrow (≈3 mG wide) hole in the ESR line. We studied relaxation of the holes after burning, which is caused by the nuclear spin diffusion. Analyzing the dynamics of the hole in the spectrum with a simple one-dimensional diffusion model leads to a value of the diffusion coefficient D = 8(3) × 10-9 G2 s-1. Our data indicate that the spin diffusion is not completely prevented even in the frozen core near the donors. The emergence of the narrow hole after the Overhauser DNP may be explained by a partial "softening" of the frozen core caused by decoupling of the donor electron and remote 29Si nuclei.
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Affiliation(s)
- J Järvinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
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Maksniemi E, Hietajärvi L, Salonen V, Järvinen J, Ketonen E, Lonka K, Salmela-Aro K. Evening activities and sleep in late adolescence - ecological ambulatory assessment approach. Sleep Med 2019. [DOI: 10.1016/j.sleep.2019.11.673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sheludiakov S, McColgan PT, Lee DM, Khmelenko VV, Järvinen J, Ahokas J, Vasiliev S. Formation of Nuclear-Polarized Phases of H Atoms Embedded in Solid H_{2} Films. Phys Rev Lett 2019; 122:225301. [PMID: 31283268 DOI: 10.1103/physrevlett.122.225301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/20/2019] [Indexed: 06/09/2023]
Abstract
We report on an experimental observation of two phases of hydrogen atoms in solid H_{2} films at temperatures of 0.1-0.8 K, characterized by a large enhancement of the nuclear spin polarization compared to that given by Boltzmann statistics (p=0.15 at T=0.15 K). The first phase with p=0.35(5) is formed spontaneously during sample storage in a high magnetic field (B=4.6 T). The second phase with an even higher nuclear polarization, p=0.75(7), can be achieved at T≤0.55 K by repeating sequences of dynamic nuclear polarization followed by a system relaxation. Upon warming through the range 0.55-0.65 K, the highly nuclear-polarized phase undergoes a phase transition to the spontaneously polarized phase which breaks down at T≃0.8 K, and the nuclear polarization gradually converges to the Boltzmann distribution. We discuss possible scenarios for explaining the nature of the observed phenomena.
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Affiliation(s)
- S Sheludiakov
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - P T McColgan
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - V V Khmelenko
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - J Järvinen
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Ahokas
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Vasiliev
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
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7
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Siiskonen T, Ciraj-Bjelac O, Dabin J, Diklic A, Domienik-Andrzejewska J, Farah J, Fernandez J, Gallagher A, Hourdakis C, Jurkovic S, Järvinen H, Järvinen J, Knežević Ž, Koukorava C, Maccia C, Majer M, Malchair F, Riccardi L, Rizk C, Sanchez R, Sandborg M, Merce MS, Segota D, Sierpowska J, Simantirakis G, Sukupova L, Thrapsanioti Z, Vano E. Establishing the European diagnostic reference levels for interventional cardiology. Phys Med 2018; 54:42-48. [DOI: 10.1016/j.ejmp.2018.09.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/19/2018] [Accepted: 09/23/2018] [Indexed: 11/29/2022] Open
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8
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Sheludiakov S, Ahokas J, Järvinen J, Lehtonen L, Vainio O, Vasiliev S, Lee DM, Khmelenko VV. ESR study of atomic hydrogen and tritium in solid T 2 and T 2:H 2 matrices below 1 K. Phys Chem Chem Phys 2017; 19:2834-2842. [PMID: 28067930 DOI: 10.1039/c6cp06933a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on the first ESR study of atomic hydrogen and tritium stabilized in solid T2 and T2:H2 matrices down to 70 mK. The concentrations of T atoms in pure T2 approached 2 × 1020 cm-3 (0.60%) and record-high concentrations of H atoms ∼1 × 1020 cm-3 (0.33%) were reached in T2:H2 solid mixtures where a fraction of T atoms became converted into H due to the isotopic exchange reaction T + H2 → TH + H. The maximum concentrations of unpaired T and H atoms were limited by their recombination which becomes enhanced by efficient atomic diffusion due to the presence of a large number of vacancies and phonons generated in the matrices by β-particles. Recombination also appeared in an explosive manner, both being stimulated and spontaneously in thick films where sample cooling was insufficient. We suggest that the main mechanism for H and T migration is physical diffusion related to tunneling or hopping to vacant sites in contrast to tunneling chemical exchange reactions which govern diffusion of H and D atoms created in H2 and D2 matrices by other methods.
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Affiliation(s)
- S Sheludiakov
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - J Ahokas
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - J Järvinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - L Lehtonen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - O Vainio
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - S Vasiliev
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - D M Lee
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
| | - V V Khmelenko
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
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9
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Sheludiakov S, Ahokas J, Järvinen J, Zvezdov D, Lehtonen L, Vainio O, Vasiliev S, Lee DM, Khmelenko VV. Tunneling chemical exchange reaction D + HD → D 2 + H in solid HD and D 2 at temperatures below 1 K. Phys Chem Chem Phys 2016; 18:29600-29606. [PMID: 27752662 DOI: 10.1039/c6cp05486b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on a study of the exchange tunneling reaction D + HD → D2 + H in a pure solid HD matrix and in a D2 matrix with a 0.23% HD admixture at temperatures between 130 mK and 1.5 K. We found that the exchange reaction rates, kexHD ∼ 3 × 10-27 cm3 s-1 in the pure HD matrix, and kexD2 = 9(4) × 10-28 cm3 s-1 in the D2 matrix, are nearly independent of temperature within this range. This confirms the quantum tunnelling nature of these reactions, and their ability to proceed at temperatures down to absolute zero. Based on these observations we concluded that exchange tunneling reaction H + H2 → H2 + H should also proceed in a H2 matrix at the lowest temperatures. On the other hand, the recombination of H atoms in solid H2 and D atoms in solid D2 is substantially suppressed at the lowest temperatures as a result of a decreased probability of resonant tunneling of atoms when they approach each other.
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Affiliation(s)
- S Sheludiakov
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - J Ahokas
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - J Järvinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - D Zvezdov
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland. and Institute of Physics, Kazan Federal University, 18 Kremlyovskaya St., Kazan 42008, Republic of Tatarstan, Russian Federation
| | - L Lehtonen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - O Vainio
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - S Vasiliev
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland.
| | - D M Lee
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
| | - V V Khmelenko
- Institute for Quantum Science and Engineering, Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843, USA
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Vainio O, Ahokas J, Järvinen J, Lehtonen L, Novotny S, Sheludiakov S, Suominen KA, Vasiliev S, Zvezdov D, Khmelenko VV, Lee DM. Bose-Einstein condensation of magnons in atomic hydrogen gas. Phys Rev Lett 2015; 114:125304. [PMID: 25860755 DOI: 10.1103/physrevlett.114.125304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Indexed: 06/04/2023]
Abstract
We report on experimental observation of Bose-Einstein condensation (BEC)-like behavior of quantized electron spin waves (magnons) in a dense gas of spin-polarized atomic hydrogen. The magnons are trapped and controlled with inhomogeneous magnetic fields and described by a Schrödinger-like wave equation, in analogy to the BEC experiments with neutral atoms. We have observed the appearance of a sharp feature in the ESR spectrum displaced from the normal spin wave spectrum. We believe that this observation corresponds to a sudden growth of the ground-state population of the magnons and emergence of their spontaneous coherence for hydrogen gas densities exceeding a critical value, dependent on the trapping potential. We interpret the results as a BEC of nonequilibrium magnons which were formed by applying the rf power.
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Affiliation(s)
- O Vainio
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Ahokas
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Järvinen
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - L Lehtonen
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Novotny
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Sheludiakov
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - K-A Suominen
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Vasiliev
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - D Zvezdov
- Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
- Kazan Federal University, 18 Kremlyovskaya Street, Kazan 420008, Russia
| | - V V Khmelenko
- Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
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11
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Sheludiakov S, Ahokas J, Järvinen J, Zvezdov D, Vainio O, Lehtonen L, Vasiliev S, Mao S, Khmelenko VV, Lee DM. Dynamic nuclear polarization of high-density atomic hydrogen in solid mixtures of molecular hydrogen isotopes. Phys Rev Lett 2014; 113:265303. [PMID: 25615349 DOI: 10.1103/physrevlett.113.265303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Indexed: 06/04/2023]
Abstract
We report on magnetic resonance studies of high-density atomic hydrogen and deuterium in solid hydrogen matrices at temperatures below 1 K. Average concentrations of H atoms ≈3×10(19) cm(-3) are obtained in chemical tunneling reactions of isotope exchange with D atoms. The products of these reactions are closely located pairs of H atoms near D2 molecules with strong exchange interactions. We discovered a dynamic nuclear polarization effect on H atoms created by pumping the center of the H electron spin resonance spectrum, similar to the Overhauser effect in metals. Our results indicate that H atoms may be arranged inside molecular matrices at separations equivalent to local concentrations of 2.6×10(21) cm(-3). This opens up a way to build a metallic state of atomic hydrogen at zero pressure.
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Affiliation(s)
- S Sheludiakov
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland
| | - J Ahokas
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland
| | - J Järvinen
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland
| | - D Zvezdov
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland and Institute of Physics, Kazan Federal University, 18 Kremlyovskaya Street, Kazan 42008, Republic of Tatarstan, Russian Federation
| | - O Vainio
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland
| | - L Lehtonen
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland
| | - S Vasiliev
- Department of Physics and Astronomy, Wihuri Physical Laboratory, University of Turku, 20014 Turku, Finland
| | - S Mao
- Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - V V Khmelenko
- Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Department of Physics and Astronomy, Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
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Sheludiakov S, Ahokas J, Vainio O, Järvinen J, Zvezdov D, Vasiliev S, Khmelenko VV, Mao S, Lee DM. Experimental cell for molecular beam deposition and magnetic resonance studies of matrix isolated radicals at temperatures below 1 K. Rev Sci Instrum 2014; 85:053902. [PMID: 24880382 DOI: 10.1063/1.4875985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present the design and performance of an experimental cell constructed for matrix isolation studies of H and D atoms in solid H2/D2 films, which are created by molecular beam deposition at temperatures below 1 K. The sample cell allows sensitive weighing of the films by a quartz microbalance (QM) and their studies by magnetic resonance techniques in a strong magnetic field of 4.6 T. We are able to regulate the deposition rate in the range from 0.01 to 10 molecular layers/s, and measure the thickness with ≈0.2 monolayer resolution. The upper QM electrode serves as a mirror for a 128 GHz Fabry-Perot resonator connected to an electron spin resonance (ESR) spectrometer. H and D atoms were created by RF discharge in situ in the sample cell, and characterized by ESR and electron-nuclear double resonance. From the magnetic resonance measurements we conclude that the films are smooth and provide homogeneous trapping conditions for embedded atoms. The current sample cell design also makes it possible to calibrate the ESR signal and estimate the average and local concentrations of H and D radicals in the film.
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Affiliation(s)
- S Sheludiakov
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Ahokas
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - O Vainio
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - J Järvinen
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - D Zvezdov
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - S Vasiliev
- Wihuri Physical Laboratory, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - V V Khmelenko
- Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - S Mao
- Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Department of Physics and Astronomy and Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
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Ahokas J, Järvinen J, Shlyapnikov GV, Vasiliev S. Clock shift in high field magnetic resonance of atomic hydrogen. Phys Rev Lett 2008; 101:263003. [PMID: 19437640 DOI: 10.1103/physrevlett.101.263003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We have measured electron spin resonance line shifts due to collisions in atomic hydrogen gas compressed to densities approximately 10(18) cm(-3) in a strong magnetic field (4.6 T). The shift in a doubly polarized gas is negligible, in contrast with a mixture of two hyperfine states. This difference is explained by properly including effects of quantum statistics in atomic collisions and magnetic dipolar effects. We report on the first direct measurement of the difference between the triplet and singlet s-wave scattering lengths a(t) - a(s) = 60(10) pm, which is in agreement with existing theories.
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Affiliation(s)
- J Ahokas
- Wihuri Physical Laboratory, Department of Physics, University of Turku, 20014 Turku, Finland
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14
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Abstract
We report a measurement of the cold collision frequency shift in atomic hydrogen gas adsorbed on the surface of superfluid (4)He at T approximately < 90 mK. Using two-photon electron and nuclear magnetic resonance in 4.6 T field we separate the resonance line shifts due to the dipolar and exchange interactions, both proportional to surface density sigma. We find the clock shift Delta nu(c) = -1.0(1) x 10(-7) Hz cm(-2) x sigma, which is about 100 times smaller than the value predicted by the mean field theory and known scattering lengths in the three-dimensional case.
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Affiliation(s)
- J Ahokas
- Wihuri Physical Laboratory, Department of Physics, University of Turku, 20014 Turku, Finland
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Ahokas J, Järvinen J, Khmelenko VV, Lee DM, Vasiliev S. Exotic behavior of hydrogen atoms in solid H2 at temperatures below 1 K. Phys Rev Lett 2006; 97:095301. [PMID: 17026374 DOI: 10.1103/physrevlett.97.095301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 07/04/2006] [Indexed: 05/12/2023]
Abstract
We present the first magnetic resonance study of atomic hydrogen embedded in solid H2 films for temperatures 150-900 mK. We found that at T approximately 150 mK average concentrations of H atoms of order 10(18 cm(-3) are very stable against recombination during two weeks of observations. The distribution of the population of the two lowest hyperfine states is found to be non-Boltzmann, with a very large occupation of the ground state. We consider the possibility of formation in solid H2 of regions with high local concentrations of H atoms, where collective quantum phenomena might occur.
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Affiliation(s)
- J Ahokas
- Wihuri Physical Laboratory, Department of Physics, University of Turku, 20014 Turku, Finland
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Vasilyev S, Järvinen J, Safonov AI, Kharitonov AA, Lukashevich II, Jaakkola S. Electron-spin-resonance instability in two-dimensional atomic hydrogen gas. Phys Rev Lett 2002; 89:153002. [PMID: 12365985 DOI: 10.1103/physrevlett.89.153002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2002] [Indexed: 05/23/2023]
Abstract
We study by electron-spin-resonance spin-polarized atomic hydrogen adsorbed on the surface of superfluid helium at temperatures T(S) from 50 to 110 mK. The average dipolar field in this 2D system shifts the electron-spin-resonance peak of the adsorbed atoms relative to that of bulk atoms. The shift is directly proportional to surface density. The role of longitudinal magnetization relaxation is played by particle exchange between the 2D and the 3D phases, which diminishes exponentially with decreasing T(S). Therefore at T(S) less, similar 80 mK an excitation field of 0.1 mG disturbs the equilibrium surface density and leads to a magnetization instability observed as sawtooth shaped resonance lines.
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Affiliation(s)
- S Vasilyev
- Wihuri Physical Laboratory, Department of Physics, University of Turku, Finland
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Abstract
A prototype for a new noise helmet was developed because high noise levels were not sufficiently attenuated by commercially available helmets. The new helmet was designed to be tight, especially in the area of the throat and face, and to cover the entire head. The noise attenuation properties of the new helmet were tested against pink noise in an anechoic room, jet engine noise, and low-frequency noise with the test subjects wearing a miniature microphone under the protector. The new helmet provides insertion loss of over 50 dB, which is 18-29 dB more attenuation than that of the tested earmuffs in the frequency range of 1-8 kHz. It is also better (8-13 dB) than the tested earmuffs at frequencies of 125-1000 Hz, and it protects against air impurities because the air fed into the helmet is filtered.
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Affiliation(s)
- R Pääkkönen
- Tampere Regional Institute of Occupational Health, Finland
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Abstract
A quantitative, semiautomatic analysis of histologic features of the specific inflammatory changes occurring on the dorsum of human tongue was made for 37 tongues. Well-documented histologic differences between clinically normal appearing tongue (control), atrophic, geographic and fissured tongue were shown quantitatively. The epithelium of atrophic tongue was thinner compared to the controls. Reduction of the thickness was due to the shortened or totally missing rete pegs. Epithelium of geographic and fissured tongue showed irregular rete pegs. In fissured tongue heavy inflammation seemed to shorten the rete pegs. In atrophic tongue the connective tissue was thicker compared to the controls. This could be due to mild, chronic inflammation causing loose connective tissue described in atrophic tongue. Muscle cells of geographic tongue appeared to be as in the controls, whereas in atrophic and fissured tongue the uppermost muscle cells were small and separated compared to the controls.
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Affiliation(s)
- J Järvinen
- Department of Oral Surgery, University of Kuopio, Finland
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Kullaa-Mikkonen A, Järvinen J. Effects of age, sex and salivary secretion on the human tongue surface. Gerodontics 1988; 4:150-3. [PMID: 3209037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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van Dijken JW, Meurman JH, Järvinen J. Effect of finishing procedures on surface textures of some resin restoratives. A comparison between new and old types of composite resins. Acta Odontol Scand 1980; 38:293-301. [PMID: 6937098 DOI: 10.3109/00016358009033596] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Evaluation were made of the effect of different finishing procedures on the surface textures of a conventional composite material, two newly introduced microfiller composite resins, a visible light polymerized resin, and a glass ionomer cement. The two micro-filler composite materials appeared to be superior in finishability compared with those materials loaded with larger filler particles. The use of fine grit devices particularly resulted in smooth surfaces. This is in contrast to the other materials which always showed rough surface textures with protruding filler particles. The use of a polishing paste improved the surface finish of the micro-filler materials in contrast to the materials with larger filler particles.
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Abstract
Ten voluntary dental students were examined by 12 teachers at the same dental clinic. Eleven items of data were subjected to a two-way analysis of variance: missing teeth, filled teeth, filled teeth surfaces, DMF and DMFS index scores, decayed surfaces (first (C 1) and second (C 2) degree caries), decayed surfaces (C 2 only), decayed approximal surfaces (C 2), decayed occlusal surfaces (C 2), decayed smooth surfaces (C 2), and teeth considered to require treatment. Significant differences were found between the subjects for all 11 items assessed. The differences between the examiners were not significant for missing teeth, filled teeth, filled surfaces, and decayed smooth surfaces, but for the other items the between-examiner variation was significant at the level P less than 0.01. In particular, great variation was found in the plans for reparative care. It is suggested that teachers should undergo a special training program in order to make more consistent clinical judgments and hence to reduce the between-dentist variation in postgraduate clinical practice. This would probably be beneficial to the patients.
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