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Schliesser JM, Woodfield BF. Development of a Debye heat capacity model for vibrational modes with a gap in the density of states. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:285402. [PMID: 26126165 DOI: 10.1088/0953-8984/27/28/285402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Low-energy vibrational modes that have a gap in the density of states (DOS) have often been observed in heat capacity data in the form of 'boson' peaks, but the functions used to model these modes are often inadequate or are not physically meaningful. We have adapted the Debye model to represent these gapped modes and have derived the heat capacity equations for these modes in one, two, and three dimensions. Applying these equations to the low-temperature heat capacity data fitting for a large variety of materials substantially improves the fit quality relative to conventional fits. From the fitting parameters, the underlying DOS were estimated, which we show to be comparable to those reported in the literature. This model expands the methods of theoretical low-temperature heat capacity data analysis and improves the procedure of approximating a material's DOS from its low-temperature heat capacity.
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Affiliation(s)
- Jacob M Schliesser
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
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Pauwels E, De Cooman H, Waroquier M, Hole EO, Sagstuen E. Solved? The reductive radiation chemistry of alanine. Phys Chem Chem Phys 2014; 16:2475-82. [DOI: 10.1039/c3cp54441a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Merunka D, Kveder M, Jokić M, Rakvin B. Effect of glassy modes on electron spin-lattice relaxation in solid ethanol. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 228:50-58. [PMID: 23357426 DOI: 10.1016/j.jmr.2012.12.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 06/01/2023]
Abstract
Electron spin-lattice relaxation (SLR) of TEMPO radical was measured in the crystalline and glassy states of deuterated ethanol in the temperature range 5-80K using X-band electron paramagnetic resonance (EPR). The measured SLR rates are higher in the glassy than in crystalline state and the excess SLR rate in glassy state is much lower than in ethanol. This result suggests that extra modes in glassy state, i.e. glassy modes, produce the excess SLR rate via the electron-nuclear dipolar (END) interaction between the electron spin of radical and the matrix protons or deuterons. Using the soft-potential model and assuming the END interaction between the electron spin and the matrix protons, the contributions to SLR rate of various mechanisms of glassy modes were theoretically analyzed. The evaluations of SLR rates in glassy ethanol indicate two main mechanisms of glassy modes: thermally activated relaxation of double-well systems and phonon-induced relaxation of quasi-harmonic local modes. The SLR rates induced by these mechanisms correlate well with the experimental data.
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Affiliation(s)
- Dalibor Merunka
- Ruer Bošković Institute, Bijenička cesta 54, HR-10000 Zagreb, Croatia.
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Maltar-Strmečki N, Rakvin B. Investigation of the nitrogen hyperfine coupling of the second stable radical in γ-irradiated l-alanine crystals by 2D-HYSCORE spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 222:81-87. [PMID: 22854218 DOI: 10.1016/j.jmr.2012.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 06/28/2012] [Accepted: 06/30/2012] [Indexed: 06/01/2023]
Abstract
The second stable radical, NH(3)(+)C()(CH(3))COO(-), R2, in the γ-irradiated single crystal of l-alanine and its fully (15)N-enriched analogue were studied by an advanced pulsed EPR technique, 2D-HYSCORE (two-dimensional hyperfine sublevel correlation) spectroscopy at 200K. The nitrogen hyperfine coupling tensor of the R2 radical was determined from the HYSCORE data and provides new experimental data for improved characterization of the R2 radical in the crystal lattice. The results obtained complement the experimental proton data available for the R2 radical and could lead to increased accuracy and reliability of EPR spectrum simulations.
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Mendes G, Albuquerque E, Fulco U, Bezerril L, Caetano E, Freire V. Electronic specific heat of an α3-helical polypeptide and its biochemical variants. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.06.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kveder M, Merunka D, Ilakovac A, Rakvin B. A multi-frequency EPR spectroscopy approach in the detection of boson peak excitations. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 213:26-31. [PMID: 21940185 DOI: 10.1016/j.jmr.2011.08.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/04/2011] [Accepted: 08/23/2011] [Indexed: 05/31/2023]
Abstract
The influence of boson peak (BP) excitations on low-temperature spin-lattice relaxation rate of a paramagnetic center embedded in a glassy matrix is investigated in the context of multi-frequency electron paramagnetic resonance (EPR) detection. In the theoretical analysis, the transition rate of spin one-half in the presence of a phonon field is calculated within the approximation of Fermi's golden rule. Several phonon densities of states are compared, among which one originating from a model of quasi-localized vibrations has been introduced into electron spin relaxation formalism for the first time. The respective frequency dependencies of spin-lattice relaxation rates are predicted which should lead to observable effects of BP modes if a multi-frequency study at very low temperatures is performed.
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Affiliation(s)
- Marina Kveder
- Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
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Rakvin B, Maltar-Strmečki N, KattNig D, Grampp G. ENDOR study of the dynamic properties of stable paramagnetic centres in γ -irradiated L-alanine crystals. Mol Phys 2010. [DOI: 10.1080/00268970701616048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Rakvin B, Maltar-Strmečki N, Kattnig D, Grampp G. ENDOR Study on the Dynamic Properties of the First Stable Paramagnetic Center in γ-Irradiated l-Alanine Crystals. J Phys Chem A 2010; 114:7500-5. [DOI: 10.1021/jp103883x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Boris Rakvin
- Ruđer Bošković Institute, P.O. Box 180, 10002, Zagreb, Croatia, Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002, Zagreb, Croatia, and Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstrasse 4/I, A-8010 Graz, Austria
| | - Nadica Maltar-Strmečki
- Ruđer Bošković Institute, P.O. Box 180, 10002, Zagreb, Croatia, Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002, Zagreb, Croatia, and Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstrasse 4/I, A-8010 Graz, Austria
| | - Daniel Kattnig
- Ruđer Bošković Institute, P.O. Box 180, 10002, Zagreb, Croatia, Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002, Zagreb, Croatia, and Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstrasse 4/I, A-8010 Graz, Austria
| | - Günter Grampp
- Ruđer Bošković Institute, P.O. Box 180, 10002, Zagreb, Croatia, Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002, Zagreb, Croatia, and Institute of Physical and Theoretical Chemistry, Graz University of Technology, Technikerstrasse 4/I, A-8010 Graz, Austria
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de Souza JM, Freire PTC, Argyriou DN, Stride JA, Barthès M, Kalceff W, Bordallo HN. Raman and Neutron Scattering Study of Partially Deuterated L-Alanine: Evidence of a Solid-Solid Phase Transition. Chemphyschem 2009; 10:3337-43. [DOI: 10.1002/cphc.200900482] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kolesov BA, Boldyreva EV. Difference in the Dynamic Properties of Chiral and Racemic Crystals of Serine Studied by Raman Spectroscopy at 3−295 K. J Phys Chem B 2007; 111:14387-97. [DOI: 10.1021/jp076083o] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- B. A. Kolesov
- Institute of Inorganic Chemistry, SB RAS, Lavrent'eva 3, Novosibirsk 630090, Institute of Solid State Chemistry and Mechanochemistry, SB RAS, Kutateladze 18, Novosibirsk 630128, and REC-008, Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
| | - E. V. Boldyreva
- Institute of Inorganic Chemistry, SB RAS, Lavrent'eva 3, Novosibirsk 630090, Institute of Solid State Chemistry and Mechanochemistry, SB RAS, Kutateladze 18, Novosibirsk 630128, and REC-008, Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia
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Rakvin B, Maltar-Strmečki N, Nakagawa K. Pulsed EPR study of low-dose irradiation effects in L-alanine crystals irradiated with -rays, Ne and Si ion beams. RADIAT MEAS 2007. [DOI: 10.1016/j.radmeas.2007.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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de Souza JM, Freire PTC, Bordallo HN, Argyriou DN. Structural isotopic effects in the smallest chiral amino acid: observation of a structural phase transition in fully deuterated alanine. J Phys Chem B 2007; 111:5034-9. [PMID: 17439273 DOI: 10.1021/jp070366z] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A first study of possible changes instigated by deuteration in amino acids was carried out using neutron diffraction, inelastic neutron scattering, and Raman scattering in l-alanine, C2H4(NH2)COOH. Careful analysis of the structural parameters shows that deuteration of l-alanine engenders significant geometric changes as a function of temperature, which can be directly related to the observation of new lattice vibration modes in the Raman spectra. The combination of the experimental data suggests that C2D4(ND2)COOD undergoes a structural phase transition (or a structural rearrangement) at about 170 K. Considering that this particular amino acid is a hydrogen-bonded system with short hydrogen bonds (O...H approximately 1.8 A), we evoke the Ubbelohde effect to conclude that substitution of hydrogen for deuterium gives rise to changes in the hydrogen-bonding interactions. The structural differences suggest distinct relative stabilities for the hydrogenous and deuterated l-alanine.
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Maltar-Strmecki N, Rakvin B. Evidence for disorder in L-alanine lattice detected by Pulsed-EPR spectroscopy at cryogenic temperatures. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2006; 63:784-7. [PMID: 16455297 DOI: 10.1016/j.saa.2005.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Revised: 09/23/2005] [Accepted: 10/01/2005] [Indexed: 05/06/2023]
Abstract
The unusual behavior of lattice dynamics of L-alanine has been assigned to intermolecular dynamics and localization of vibrational energy. Recent heat capacity and Pulsed-EPR measurements support presence of thermally activated dynamic orientational disorder in the L-alanine lattice below 20 K. In the present study, the additional evidence for possible thermally activated disordered behavior of L-alanine lattice have been obtained by investigating dependences of longitudinal relaxation time of first stable L-alanine radical, SAR1, on sample cooling rates for the same low temperature interval. The obtained relaxation time by Pulsed-EPR shows clear dependence on cooling rates and this behavior can be explained within two types of suggested spin-lattice relaxation mechanisms for the paramagnetic centers in the hydrogen-bonded organic crystal.
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Affiliation(s)
- N Maltar-Strmecki
- Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002 Zagreb, Croatia
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Direct evidence for the glass-crystalline transformation in solid ethanol by means of a nitroxide spin probe. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.11.055] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rakvin B, Maltar-Strmečki N. Study of the first stable l-alanine paramagnetic center by 2D-HYSCORE spectroscopy: Detection of 14N hyperfine and quadrupole splitting. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.08.138] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Maltar-Strmecki N, Rakvin B. Thermal stability of radiation-induced free radicals in gamma-irradiated L-alanine single crystals. Appl Radiat Isot 2005; 63:375-80. [PMID: 15950480 DOI: 10.1016/j.apradiso.2005.04.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 04/19/2005] [Accepted: 04/19/2005] [Indexed: 11/19/2022]
Abstract
Decay of the radiation-induced stable free radicals in l-alanine single crystals and powders at the temperatures from 379 to 476 K was examined by electron paramagnetic resonance. For single crystals, the calculated activation energy of the radical decay is 104.3+/-1.7 kJ/mol (i.e. 12 538+/-202 K) and the frequency factor lnv (O) is 24.1+/-0.4 min(-1). The lifetime of the radical in single crystals at 296 K is 162 years. The results confirm the long-term stability of the radicals, but the decay was found to be faster in large crystals than in powders.
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Affiliation(s)
- N Maltar-Strmecki
- Faculty of Veterinary Medicine, University of Zagreb, P.O. Box 466, 10002 Zagreb, Croatia
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