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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:17 |
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Conference: Bucharest University Faculty of Physics 2012 Meeting
Section: Atomic and Molecular Physics; Astrophysics
Title:
Dynamical line shifts of nistroxide HF-EPR spectra:an experimental and analytical study
Authors:
V.BERCU (1), M.MARTINELLI (2), L.PARDI (2), C.A.MASSA (2), D.LEPORINI (3)
Affiliation:
(1) University of Bucharest, Department of Structure of the Matter, Earth and Atmospheric Physics, Astrophysics, P.O. Box MG-11, 077125 Măgurele (Ilfov),Romania.
(2) Istituto per i processi Chimico-Fisici(IPCF-CNR), G.Moruzzi, 1, 56124 Pisa, Italy.
(3) Dipartimento di Fisica ”Enrico Fermi”, Universita di Pisa, Largo B.Pontecorvo, 3, 56127 Pisa, Italy.
E-mail
vasile.bercu@fizica.unibuc.ro
Keywords:
EPR spectroscopy; nitroxide spin probe
Abstract:
The high-field high-frequency Electron Spin Resonance spectroscopy (HF-ESR) is a powerful tool to investigate, with ultra-high angular resolution, the rotational dynamics of complex systems like polymers, viscous fluids and glasses. Usually, information is drawn by detailed numerical analysis of the overall line-shape. Here, we present a simplified analytical model addressing the line shifts due to the dynamics of the paramagnetic center. The model captures the basic features of the reorientation process ( time scale and size of the angular jump). It is compared with experimental results concerning the reorientation of a paramagnetic guest molecule dissolved in polystyrene. We find that the best-fit parameters yield equally acceptable best-fits of the overall spectrum by numerical simulations and dynamical line shifts by independent analytic expressions.
Note: This work was supported by the strategic grant POSDRU/89/1.5/S/58852, Project "Postdoctoral programme for training scientific researchers" co-financed by the European Social Fund within the Sectorial Operational Program for Human Resources Development 2007 – 2013.
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