IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
PROTON QUANTUM QUASI-EQUILIBRIUM STATES IN LIQUID CRYSTALS: ANALYTICAL ? EXPERIMENTAL STUDY
Autor/es:
CLAUDIO J. BONIN; CECILIA E. GONZÁLEZ; HÉCTOR H. SEGNORILE; RICARDO C. ZAMAR
Lugar:
Alta Gracia
Reunión:
Workshop; Magnetic Resonance in a Cordubensis Perspective: New Developments in NMR; 2011
Institución organizadora:
ISMAR - FaMAF
Resumen:
Proton spins of liquid crystal (LC) molecules are small clusters of strongly interacting spins (dipole-dipole), magnetically isolated in the average from spins at other molecules, while mechanically coupled with an orientationally ordered molecular environment. Previous work1 showed that quasi-equilibrium states (quasi-invariants (QI)) associated with constants of motion of the residual dipolar Hamiltonian HD0, can be prepared in LC through the Jeener-Broekaert (JB) experiment2. An efficient application of the QI in many fields, from the basic physics of open quantum systems and quantum information processing, to the study of cooperative molecular dynamics, demands a complete analytical description of these QI. We study the proton spin dynamics and report the first complete characterization of a multi-spin-order QI in a spherical tensor operator basis, in a 4-spin-1/2 model, as a first approach for a typical LC (e.g. PAAd6). The experiments show that coherence order of dipolar NMR signals increase with the preparation  period, t1. At longer t1  the experiment in PAAd6 and other LC cannot be explained by assuming only two QI, demanding the consideration of additional QI´s of more complex tensor structure5.