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Mutunga FM, Olenyik KM, Strom AI, Anderson DT. Hydrogen atom quantum diffusion in solid parahydrogen: The H + N 2O → cis-HNNO → trans-HNNO reaction. J Chem Phys 2021; 154:014302. [PMID: 33412886 DOI: 10.1063/5.0028853] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The diffusion and reactivity of hydrogen atoms in solid parahydrogen at temperatures between 1.5 K and 4.3 K are investigated by high-resolution infrared spectroscopy. Hydrogen atoms are produced within solid parahydrogen as the by-products of the 193 nm in situ photolysis of N2O, which induces a two-step tunneling reaction, H + N2O → cis-HNNO → trans-HNNO. The second-order rate constant for the first step to form cis-HNNO is found to be inversely proportional to the N2O concentration after photolysis, indicating that the hydrogen atoms move through solid parahydrogen via quantum diffusion. This reaction only readily occurs at temperatures below 2.8 K, not due to an increased rate constant for the first reaction step at low temperatures but rather due to an increased selectivity to the reaction. The rate constant for the second step of the reaction mechanism involving unimolecular isomerization is shown to be independent of the N2O concentration as expected. The inverse concentration dependence of the rate constant for the reaction step that involves the hydrogen atom demonstrates clearly that quantum diffusion influences the reactivity of the hydrogen atoms in solid parahydrogen, which does not have an analogy in classical reaction kinetics.
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Affiliation(s)
| | - Kelly M Olenyik
- Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA
| | - Aaron I Strom
- Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA
| | - David T Anderson
- Department of Chemistry, University of Wyoming, Laramie, Wyoming 82071, USA
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McColgan PT, Meraki A, Boltnev RE, Lee DM, Khmelenko VV. Luminescence of Molecular Nitrogen Nanoclusters Containing Stabilized Atoms. J Phys Chem A 2017; 121:9045-9057. [PMID: 29112821 DOI: 10.1021/acs.jpca.7b09661] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We studied the luminescence of molecular nitrogen nanoclusters containing stabilized nitrogen, oxygen, hydrogen, and deuterium atoms. Optical spectra were observed during the destruction of these ensembles of nanoclusters accompanied by a rapid release of chemical energy stored in the samples. Several interesting features were observed including a broad band near λ ≈ 360 nm, which was identified as emission corresponding to 2Ag→1Ag transition of N4(D2h) polymeric nitrogen. Also the sharp lines at λ ∼ 336 and 473 nm were observed, and their assignments to ND radicals are discussed.
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Affiliation(s)
- Patrick T McColgan
- Department of Physics and Astronomy and Institute for Quantum Science & Engineering, Texas A&M University , College Station, Texas 77843, United States
| | - Adil Meraki
- Department of Physics, Bilecik University , 11210 Gülümbe, Bilecik, Turkey
| | - Roman E Boltnev
- Talrose Institute for Energy Problems of Chemical Physics, Russian Academy of Sciences , Chernogolovka, Russia.,Joint Institute for High Temperatures, Russian Academy of Sciences , Moscow, Russia
| | - David M Lee
- Department of Physics and Astronomy and Institute for Quantum Science & Engineering, Texas A&M University , College Station, Texas 77843, United States
| | - Vladimir V Khmelenko
- Department of Physics and Astronomy and Institute for Quantum Science & Engineering, Texas A&M University , College Station, Texas 77843, United States
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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] [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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Mao S, Meraki A, McColgan PT, Shemelin V, Khmelenko VV, Lee DM. Experimental setup for investigation of nanoclusters at cryogenic temperatures by electron spin resonance and optical spectroscopies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:073906. [PMID: 25085151 DOI: 10.1063/1.4891189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present the design and performance of an experimental setup for simultaneous electron spin resonance (ESR) and optical studies of nanoclusters with stabilized free radicals at cryogenic temperatures. A gas mixture of impurities and helium after passing through a RF discharge for dissociation of molecules is directed onto the surface of superfluid helium to form the nanoclusters of impurities. A specially designed ESR cavity operated in the TE011 mode allows optical access to the sample. The cavity is incorporated into a homemade insert which is placed inside a variable temperature insert of a Janis (4)He cryostat. The temperature range for sample investigation is 1.25-300 K. A Bruker EPR 300E and Andor 500i optical spectrograph incorporated with a Newton EMCCD camera are used for ESR and optical registration, respectively. The current experimental system makes it possible to study the ESR and optical spectra of impurity-helium condensates simultaneously. The setup allows a broad range of research at low temperatures including optically detected magnetic resonance, studies of chemical processes of the active species produced by photolysis in solid matrices, and investigations of nanoclusters produced by laser ablation in superfluid helium.
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Affiliation(s)
- S Mao
- Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - A Meraki
- Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - P T McColgan
- Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - V Shemelin
- Cornell Laboratory for Accelerator-based Science and Education, Cornell University, Ithaca, New York 14853, USA
| | - V V Khmelenko
- Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
| | - D M Lee
- Institute for Quantum Science and Engineering and Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, USA
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