Study of correlations in molecular motion by multiple quantum NMR

Technical Report · Sun Nov 01 04:00:00 EST 1981

DOI:https://doi.org/10.2172/5582121· OSTI ID:5582121

Tang, J H

Nuclear magnetic resonance is a very useful tool for characterizing molecular configurations through the measurement of transition frequencies and dipolar couplings. The measurement of spectral lineshapes, spin-lattice relaxation times, and transverse relaxation times also provide us with valuable information about correlations in molecular motion. The new technique of multiple quantum nuclear magnetic resonance has numerous advantages over the conventional single quantum NMR techniques in obtaining information about static and dynamic interactions of coupled spin systems. In the first two chapters, the theoretical background of spin Hamiltonians and the density matrix formalism of multiple quantum NMR is discussed. The creation and detection of multiple quantum coherence by multiple pulse sequence are discussed. Prototype multiple quantum spectra of oriented benzene are presented. Redfield relaxation theory and the application of multiple quantum NMR to the study of correlations in fluctuations are presented. A specific example of an oriented methyl group relaxed by paramagnetic impurities is studied in detail. The study of possible correlated motion between two coupled methyl groups by multiple quantum NMR is presented. For a six spin system it is shown that the four-quantum spectrum is sensitive to two-body correlations, and serves a ready test of correlated motion. The study of the spin-lattice dynamics of orienting or tunneling methyl groups (CH/sub 3/ and CD/sub 3/) at low temperatures is presented. The anisotropic spin-lattice relaxation of deuterated hexamethylbenzene, caused by the sixfold reorientation of the molecules, is investigated, and the NMR spectrometers and other experimental details are discussed.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5582121
• Report Number(s): LBL-13605; ON: DE82005650
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR MOMENTUM
AROMATICS
CORRELATIONS
COUPLING
DEUTERIUM COMPOUNDS
DIPOLES
FLUCTUATIONS
HAMILTONIANS
HYDROCARBONS
HYDROGEN COMPOUNDS
MAGNETIC RESONANCE
MATHEMATICAL OPERATORS
MEASURING INSTRUMENTS
MOLECULAR STRUCTURE
MOLECULES
MOTION
MULTIPOLES
NMR SPECTROMETERS
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
PARTICLE PROPERTIES
QUANTUM OPERATORS
RELAXATION
RESONANCE
SPECTROMETERS
SPIN
SPIN-LATTICE RELAXATION
VARIATIONS
ZEEMAN EFFECT