Category Archives: Glass

Influence of deuteration in the glassing matrix on 13C dynamic nuclear polarization

Lumata, L., M.E. Merritt, and Z. Kovacs, Influence of deuteration in the glassing matrix on 13C dynamic nuclear polarization. Phys. Chem. Chem. Phys., 2013. 15(19): p. 7032-7035.

http://www.ncbi.nlm.nih.gov/pubmed/23552448

Replacement of protons by deuterons in the glassing solvents led to 2-3-fold improvement of the (13)C dynamic nuclear polarization (DNP) solid-state NMR signal for samples doped with large electron spin resonance (ESR) linewidth free radicals galvinoxyl, DPPH, and 4-oxo-TEMPO. Meanwhile, the reverse effect is observed for (13)C DNP using small ESR linewidth free radicals BDPA and trityl OX063.

Influence of deuteration in the glassing matrix on 13C dynamic nuclear polarization

Lumata, L., M.E. Merritt, and Z. Kovacs, Influence of deuteration in the glassing matrix on 13C dynamic nuclear polarization. Phys. Chem. Chem. Phys., 2013. 15(19): p. 7032-7035.

http://www.ncbi.nlm.nih.gov/pubmed/23552448

Replacement of protons by deuterons in the glassing solvents led to 2-3-fold improvement of the (13)C dynamic nuclear polarization (DNP) solid-state NMR signal for samples doped with large electron spin resonance (ESR) linewidth free radicals galvinoxyl, DPPH, and 4-oxo-TEMPO. Meanwhile, the reverse effect is observed for (13)C DNP using small ESR linewidth free radicals BDPA and trityl OX063.

Effect of glassy modes on electron spin–lattice relaxation in solid ethanol

Merunka, D., et al., Effect of glassy modes on electron spin–lattice relaxation in solid ethanol. J. Magn. Reson., 2013. 228(0): p. 50-58.

http://www.ncbi.nlm.nih.gov/pubmed/23357426

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.

Effect of glassy modes on electron spin–lattice relaxation in solid ethanol

Merunka, D., et al., Effect of glassy modes on electron spin–lattice relaxation in solid ethanol. J. Magn. Reson., 2013. 228(0): p. 50-58.

http://www.ncbi.nlm.nih.gov/pubmed/23357426

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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