Coherent manipulation of non-thermal spin order in optical nuclear polarization experiments.
Time resolved measurements of Optical Nuclear Polarization (ONP) have been performed on hyperpolarized triplet states in molecular crystals created by light excitation. Transfer of the initial electron polarization to nuclear spins has been studied in the presence of radiofrequency excitation; the experiments have been performed with different pulse sequences using different doped molecular systems. The experimental results clearly demonstrate the dominant role of coherent mechanisms of spin order transfer, which manifest themselves in well pronounced oscillations. These oscillations are of two types, precessions and nutations, having characteristic frequencies, which are the same for the different molecular systems and the pulse sequences applied. Hence, precessions and nutations constitute a general feature of polarization transfer in ONP experiments. In general, coherent manipulation of spin order transfer creates a powerful resource for improving the performance of the ONP method, which paves the way to strong signal enhancement in nuclear magnetic resonance.
Fachbereich Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, Darmstadt 64287, Germany.
Gerd
0000000313049762
G
Buntkowsky
International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090, Russia.
Konstantin L
KL
Ivanov
Max-Planck-Institut für Medizinische Forschung, Heidelberg, Jahnstr. 29, 69120 Heidelberg, Germany.
Herbert
H
Zimmermann
International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090, Russia.
Hans-Martin
0000000265529381
HM
Vieth