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Radiation products at 77 K in trehalose single crystals: EMR and DFT analysis

(2012) JOURNAL OF PHYSICAL CHEMISTRY A. 116(13). p.3377-3387
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Abstract
The radicals obtained in trehalose dihydrate single crystals after 77 K X-irradiation have been investigated at the same temperature using X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and ENDOR-induced EPR (EIE) techniques. Five proton hyperfine coupling tensors were unambiguously determined from the ENDOR measurements and assigned to three carbon-centered radical species (T1, T1*, and T2) based on the EIE spectra. EPR angular variations revealed the presence of four additional alkoxy radical species (T3 to T6) and allowed determination of their g tensors. Using periodic density functional theory (DFT) calculations, T1/T1*, T2, and T3 were identified as H-loss species centered at C4, C1', and O2', respectively. The T4 radical is proposed to have the unpaired electron at O4, but considerable discrepancies between experimental and calculated HFC values indicate it is not simply the (net) H-loss species. No suitable models were found for T5 and T6. These exhibit a markedly larger g anisotropy than T3 and T4, which were not reproduced by any of our DFT calculations.
Keywords
ALKOXY RADICALS, SPIN-RESONANCE, MAGNETIC-RESONANCE, FREE-RADICALS, PROTON HYPERFINE COUPLINGS, SPACE GAUSSIAN PSEUDOPOTENTIALS, ELECTRON-PARAMAGNETIC-RESONANCE, DENSITY-FUNCTIONAL THEORY, MOLECULAR-DYNAMICS, ROOM-TEMPERATURE

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Chicago
Tarpan, Mihaela Adeluta, Hendrik De Cooman, Eli Olaug Hole, Michel Waroquier, and Freddy Callens. 2012. “Radiation Products at 77 K in Trehalose Single Crystals: EMR and DFT Analysis.” Journal of Physical Chemistry A 116 (13): 3377–3387.
APA
Tarpan, M. A., De Cooman, H., Hole, E. O., Waroquier, M., & Callens, F. (2012). Radiation products at 77 K in trehalose single crystals: EMR and DFT analysis. JOURNAL OF PHYSICAL CHEMISTRY A, 116(13), 3377–3387.
Vancouver
1.
Tarpan MA, De Cooman H, Hole EO, Waroquier M, Callens F. Radiation products at 77 K in trehalose single crystals: EMR and DFT analysis. JOURNAL OF PHYSICAL CHEMISTRY A. 2012;116(13):3377–87.
MLA
Tarpan, Mihaela Adeluta, Hendrik De Cooman, Eli Olaug Hole, et al. “Radiation Products at 77 K in Trehalose Single Crystals: EMR and DFT Analysis.” JOURNAL OF PHYSICAL CHEMISTRY A 116.13 (2012): 3377–3387. Print.
@article{2098741,
  abstract     = {The radicals obtained in trehalose dihydrate single crystals after 77 K X-irradiation have been investigated at the same temperature using X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and ENDOR-induced EPR (EIE) techniques. Five proton hyperfine coupling tensors were unambiguously determined from the ENDOR measurements and assigned to three carbon-centered radical species (T1, T1*, and T2) based on the EIE spectra. EPR angular variations revealed the presence of four additional alkoxy radical species (T3 to T6) and allowed determination of their g tensors. Using periodic density functional theory (DFT) calculations, T1/T1*, T2, and T3 were identified as H-loss species centered at C4, C1', and O2', respectively. The T4 radical is proposed to have the unpaired electron at O4, but considerable discrepancies between experimental and calculated HFC values indicate it is not simply the (net) H-loss species. No suitable models were found for T5 and T6. These exhibit a markedly larger g anisotropy than T3 and T4, which were not reproduced by any of our DFT calculations.},
  author       = {Tarpan, Mihaela Adeluta and De Cooman, Hendrik and Hole, Eli Olaug and Waroquier, Michel and Callens, Freddy},
  issn         = {1089-5639},
  journal      = {JOURNAL OF PHYSICAL CHEMISTRY A},
  language     = {eng},
  number       = {13},
  pages        = {3377--3387},
  title        = {Radiation products at 77 K in trehalose single crystals: EMR and DFT analysis},
  url          = {http://dx.doi.org/10.1021/jp300979g},
  volume       = {116},
  year         = {2012},
}

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