title: Fingerprints of damped quantum rotation observed in solid-state proton NMR spectra.
abstract: (1)H NMR spectra of the methyl group in an oriented crystal sample of methylmalonic acid with all three non-methyl protons replaced by deuterons are interpreted in terms of the damped quantum rotation (DQR) theory of NMR line shapes. The DQR approach offers a perfect theoretical reproduction of the observed spectra while the conventional Alexander-Binsch line-shape model shows evident defects in the present case. The temperature trends of the quantities characterizing the coherent and incoherent dynamics of the methyl group in the DQR approach (the effective tunnelling frequency and two coherence-damping rates) derived from the spectra are fairly reproduced using a model reported previously. The present findings provide further evidence of limitations to the validity of the common belief that molecular rate processes in condensed phases are necessarily classical.
authors.affiliation: Max-Planck Institute for Medical Research, 69120 Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Gutsche
authors.forename: Heike
authors.initials: H
authors.lastname: Schmitt
authors.forename: Ulrich
authors.initials: U
authors.lastname: Haeberlen
authors.forename: Tomasz
authors.initials: T
authors.lastname: Ratajczyk
authors.forename: Slawomir
authors.initials: S
authors.lastname: Szymanski
mesh_terms: D003198:Computer Simulation; D003903:Deuterium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008764:Methylmalonic Acid / Q000737:chemistry; D008956:Models, Chemical; D011522:Protons; D011789:Quantum Theory; D012399:Rotation; D012680:Sensitivity and Specificity
chemical_list: D011522:Protons; D008764:Methylmalonic Acid; D003903:Deuterium