Deuteron spin alignment: A probe for studying ultraslow motions in solids and solid polymers
15 Jun 1980-Journal of Chemical Physics (American Institute of PhysicsAIP)-Vol. 72, Iss: 12, pp 6755-6762
TL;DR: In this article, the Jeener-Broekaert pulse sequence was used to detect deuteron line shapes, from which the orientational distribution of partially ordered solids or solid polymers may be determined.
Abstract: Deuteron spin alignment offers a new possibility to investigate extremely slow rotational motions in solids and solid polymers. A convenient theoretical description of the creation and detection of spin alignment by application of the Jeener–Broekaert pulse sequence is given for both static and slowly time dependent quadrupole coupling, as well as for spin–lattice relaxation of spin alignment. It is shown that the NMR signal following spin alignment yields a correlation function of the time dependent quadrupole coupling. This correlation function is evaluated explicitly for a deuteron on the corner of a regular tetrahedron undergoing tetrahedral jumps. Various applications of deuteron spin alignment are demonstrated experimentally, e.g., its use to obtain undistorted deuteron line shapes, from which the orientational distribution of partially ordered solids or solid polymers may be determined. In solid polyethylene it is shown that not only the deuterons in the crystalline regions but those in the mobile ...
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TL;DR: In this article, self diffusion coefficients in supercooled orthoterphenyl (OTP) have been determined down to 3·10−14 m2s−1 using a 1H-NMR technique applying static field gradients up to 53T m−1.
Abstract: Self diffusion coefficients in supercooled orthoterphenyl (OTP) have been determined down toD
t
=3·10−14 m2s−1 using a1H-NMR technique applying static field gradients up to 53T m−1 In a range of more than two decades theD
t
values agree with those of photochromic tracer molecules of the same size determined by forced Rayleigh scattering down to the glass transition temperatureT
g
. A change of mechanism is found for translational diffusion atT
c
≈1.2T
g
whereD
t
is proportional to the inverse shear viscosityη
−1 atT>T
c
butD
t
∼η
ξ with ξ=0.75 atT
442 citations
TL;DR: Pulsed deuteron NMR spectroscopy is described in this paper, which has recently been developed to become a powerful tool for studying molecular dynamics in solid polymers, and motional heterogeneities in glassy polymers can be detected.
Abstract: Pulsed deuteron NMR spectroscopy is described, which has recently been developed to become a powerful tool for studying molecular dynamics in solid polymers. It is shown that by analyzing the line shapes of2H absorption spectra and spectra obtained via solid echo and spin alignment, respectively, both type and timescale of rotational motions can be determined over an extraordinary wide range of characteristic frequencies, approximately 10 MHz to 1 Hz. By applying these techniques to selectively deuterated polymers, motional mechanisms involving different segments of the monomer unit can be monitored. In addition, motional heterogeneities in glassy polymers can be detected. The information about polymer dynamics available now is illustrated by a number of experimental examples. The chain motion in the amorphous regions of linearpolyethylene is discussed in detail and it is shown that it can clearly be distinguished from the chain motion of an amorphous polymer above the glass transition, wherepolystyrene is used as an example. Localized motions in the glassy state are illustrated through the jump motion phenyl groups exhibit both in the main chain (polycarbonate) and as a side group (polystyrene). The latter polymers also serve as examples for detecting motional heterogeneity. Finally, the mobility in novel classes of systems,liquid crystalline polymers andpolymer model membranes as revealed by2H NMR are described.
388 citations
TL;DR: This review intends to present solid-state 1H DQ and MQ MAS spectroscopy in a systematic fashion with a particular emphasis on methodological aspects, followed by an overview of applications.
314 citations
TL;DR: In this article, the authors investigate microscopic transport in supercooled liquids around the glass transition regime, and demonstrate that two distinct processes contribute to long-range transport in the super cooled liquid state: single-atom hopping and collective motion, the latter being the dominant process.
Abstract: The mechanisms of atomic transport in supercooled liquids and the nature of the glass transition are long-standing problems1,2,3,4. Collective atomic motion is thought to play an important role4,5,6 in both phenomena. A metallic supercooled liquid represents an ideal system for studying intrinsic collective motions because of its structural similarity to the “dense random packing of spheres” model7, which is conceptually simple. Unlike polymeric and network glasses, metallic supercooled liquids have only recently become experimentally accessible, following the discovery of bulk metallic glasses8,9,10,11,12. Here we report a 9Be nuclear magnetic resonance study of Zr-based bulk metallic glasses8,9 in which we investigate microscopic transport in supercooled liquids around the glass transition regime. Combining our results with diffusion measurements, we demonstrate that two distinct processes contribute to long-range transport in the supercooled liquid state: single-atom hopping and collective motion, the latter being the dominant process. The effect of the glass transition is clearly visible in the observed diffusion behaviour of the Be atoms.
304 citations
TL;DR: This review describes NMR spectroscopic methods for investigation of conformational dynamics together with theoretical descriptions appropriate for interpretation and simulation of the techniques, surveys the range of results available from solution and solid state NMR studies of proteins and other biomolecules, and identifies opportunities for further individual and collaborative development of solution andSolid State NMR techniques for characterizing the dynamical properties of biological macromolecules.
Abstract: NMR spectroscopy is a powerful approach for quantitating molecular conformational dynamics at multiple atomic sites and over multiple time scales. Extensive studies by solution and solid-state NMR spectroscopy of spin relaxation and line shapes in biological macromolecules have been performed in order to characterize the amplitudes, time scales, and energetics of intramolecular conformational modes and to elucidate the relationships between conformational dynamics, structure, and function. This review describes NMR spectroscopic methods for investigation of conformational dynamics together with theoretical descriptions appropriate for interpretation and simulation of the techniques, surveys the range of results available from solution and solid state NMR studies of proteins and other biomolecules, and identifies opportunities for further individual and collaborative development of solution and solid state NMR techniques for characterizing the dynamical properties of biological macromolecules.
272 citations
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2,070 citations
TL;DR: In this paper, the quadrupolar spin echo from deuterons in ordered hydrocarbon systems is shown to provide a much more reliable spectrum than the conventional free induction decay Fourier transform.
1,280 citations
TL;DR: In this paper, it was shown that rotational spin echoes provide a convenient means of studying very slow random molecular rotations (τc≲1 sec), which must be described by a proper average Hamiltonian theory.
Abstract: The NMR free induction decay from a spinning sample having inhomogeneous anisotropic interactions (chemical shifts, first order quadrupole couplings) takes the form of a train of rotational spin echoes. The Fourier transform of the echo envelope is a sharp spectrum from which the effects of anisotropy have been removed. The Fourier transform of the echo shape contains information concerning the anisotropies: This information can be extracted by a moment analysis. The effects of localized homonuclear spin–spin interactions are to convert the ’’isotropic’’ spectrum into a characteristic powder pattern. Second order quadrupole coupling produces a similar effect. It is shown in this case that the usual second‐order level shifts cannot be used to calculated this pattern, which must be described by a proper average Hamiltonian theory. Finally it is shown that rotational spin echoes provide a convenient means of studying very slow random molecular rotations (τc≲1 sec).
1,224 citations