Eur. Phys. J. B 49, 157-165 (2006)
https://doi.org/10.1140/epjb/e2006-00037-9

Time-resolved nuclear spin-dependent small-angle neutron scattering from polarised proton domains in deuterated solutions

¹ Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
² Commissariat $\rm{\grave{a}}$ l'Énergie Atomique, CEA Saclay, DSM/DRECAM/SPEC, 91191 Gif-sur-Yvette Cedex, France
³ Institut Laue Langevin, 38042 Grenoble Cedex 9, France
⁴ Institut de Biologie Structurale Jean-Pierre Ebel, CEA/CNRS/UJF, 38027 Grenoble Cedex 1, France
⁵ GKSS Forschungszentrum, 21502 Geesthacht, Germany
⁶ Technische Universität München, James-Franck-Strasse, 85748 Garching, Germany

Corresponding author: ^a andreas.michels@mx.uni-saarland.de

Received: 29 March 2005
Revised: 6 November 2005
Published online: 17 February 2006

Abstract

We have investigated the process of dynamic proton polarisation by means of time-resolved polarised small-angle neutron scattering (SANS) on frozen solutions of EHBA-Cr^V molecules in glycerol-water mixtures as a function of the concentration of EHBA-Cr^V and for different degrees of deuteration of the solvent. In the EHBA-Cr^V complex, the spins of the 20 protons which surround the paramagnetic Cr^V can be oriented using the method of dynamic nuclear polarisation (DNP), thereby offering the possibility to create locally a nuclear spin-dependent contrast for SANS. The time constants which describe the build-up of polarisation around the paramagnetic centre and the subsequent diffusion of polarisation in the solvent were determined by analysing the temporal evolution of the nuclear polarisation, which in turn was obtained by fitting a core-shell model to the time-dependent SANS curves. The results on the spin dynamics obtained using the scattering function of a core-shell could be independently confirmed by evaluating the integrated SANS intensity. A thermodynamic one-centre model is presented which is able to reproduce the observed dependence of the proton polarisation times on the proton concentration of the solvent.