Proton Magnetic Resonance Line Shape Research Articles

Low-temperature evolution of the proton magnetic resonance line shape in ?-phase palladium hydride

Measurements of the proton magnetic resonance absorption line shape in β-phase palladium hydride indicate that there is no short-range ordering associated with the order-disorder phase transition that occurs in the neighborhood of 50 K. However, measurements of the line shape in the range 10–30 K show a change from a Gaussian to a non-Gaussian profile. This effect is not related to the order-disorder phase transition. A possible explanation in terms of thermally assisted tunneling is proposed.

Indirect nuclear spin-spin interaction in CuSO4·5H2O

A study is made of the anomalous fine structure of the proton magnetic resonance line shape in CuSO4.5H2O in weak field and at low temperature. Additionally, measurements are performed on the transverse relaxation rate of the proton spins with the use of a phase coherent spectrometer. A complete explication is given of the characteristic dependence of both the continuous wave and the transient line shape on the strength and orientation of the magnetic field and the temperature. The results show that the fine structure is due to an indirect nuclear spin-spin coupling between the studied proton spins and the copper nuclear spins via the electron spins which are situated at the (12,12, 0) sites in the unit cell. The indirect spin-spin coupling has also a strong influence on the transverse relaxation rate of the proton spins.

An analysis of the NMR line shapes of the ammonium ion undergoing composite tunneling and reorientational motions at low temperatures

An analysis is made of the NMR line shapes of the rotationally tunneling ammonium (NH4+) ion which also undergoes rapid reorientataional jumps around its C3 or C2 symmetry axis. The proposed composite motion, believed to be brought about by the coupling of rotor states of the ion with lattice phonons, leads to line narrowing and offers an interpretation of experimental line shape and second moment data not explained previously. In particular, the proton resonance line shapes of (NH4)2SnCl6, NH4BF4, NH4ClO4, (NH4)2GeF6, (NH4)2PbCl6, and (NH4)2PtCl6 at liquid helium temperatures are discussed. The analysis suggests that proton magnetic resonance line shape measurements on single crystals may provide an assessment on the state of ordering of the tunneling and reorienting NH4+ ions.

NMR study of the intramolecular nonmutual exchange of 5-halobenzofuroxan. II. Mechanism of ring opening reaction.

The tautomerism of 5-chlorobenzofuroxan, 5-bromobenzofuroxan, and 5-iodobenzofuroxan was studied by the proton magnetic resonance (PMR) at 60 MHz. The rate of intramolecular rearrangement between the tautomers was calculated from the PMR line shape, using the density matrix method of intramolecular nonmutual exchange. The activation parameters for the intramolecular rearrangement were found to be ⊿H≐̸=5∼24 kcal/mol, ⊿S≐̸=-34∼+33 cal/deg·mol. Structure of the transition state is discussed from electronic energies of the system and it was concluded that this reaction proceeds via a transition state of ψ-o-dinitrosobenzene produced by the electrocyclic ring opening reaction of benzofuroxan.

Proton magnetic resonance study of ammonium ion tunnelling and its ground torsional level structure in NH 4ReO 4

The ground torsional level structure of NH + 4 in ammonium perrhenate (NH 4ReO 4) has been analysed by a study of its proton magnetic resonance lineshape in the polycrystalline state at 4 K. It is shown that, in this structure, tunneling rotation of NH + 4 around one of its C 2 axes is greatly favoured over the others.

Proton magnetic resonance line shape measurements in solid ethane

The proton magnetic resonance absorption line shape has been measured for solid ethane in the temperature range from 4 K to the melting point. The linewidth and second moment have been derived from the data. The existence of two solid phases has been confirmed; the solid–solid phase transition temperature was determined to be 89.72 ±0.05 K, and the melting point 90.37±0.05 K. The higher temperature solid phase is characterized by a narrow liquidlike resonance line indicating rapid diffusion. In the lower temperature solid phase the linewidth is much greater and it increases in two stages as the temperature is lowered to 4 K. The second moment of the line has been compared with the result of model calculations and the types of molecular motion inferred. Even at the lowest temperatures the observed second moment is much less than would be appropriate for a rigid lattice; this is interpreted in terms of tunneling of the molecules about their threefold symmetry axes.

An NMR study of molecular reorientation processes in solid n-butane

Proton magnetic resonance line shapes for polycrystalline n-butane have been studied over the temperature interval 20 K to the melting point. Spin–lattice relaxation time measurements have been made in the low temperature solid phase but no minimum found. The results show that methyl group tunneling persists to very low temperatures at a rate sufficiently high to narrow the absorption spectrum. In the high temperature solid phase long axis rotational motion of the molecules occurs. A model for this form of motion is discussed.

Proton magnetic resonance line shapes of water and ammonium ions in type-Y zeolites

Proton magnetic resonance line shapes of water and ammonium ions in type-Y zeolites

Tunneling frequencies of the ammonium ion in a tetrahedral crystalline field

The tunneling frequencies of the ammonium ion in a tetrahedral crystalline field have been computed as a function of the barrier to rotation and the librational frequency. For NH4I, the tunneling frequency determined by the analysis of the proton magnetic resonance line shapes is in good agreement with the predicted value.

ChemInform Abstract: MEASUREMENT BY PROTON MAGNETIC RESONANCE LINE SHAPE ANALYSIS OF A SMALL BARRIER TO INTERNAL ROTATION IN N,N′‐DI‐TERT.‐BUTYLTHIOUREA

Chemischer InformationsdienstVolume 5, Issue 29 Physical Organic Chemistry ChemInform Abstract: MEASUREMENT BY PROTON MAGNETIC RESONANCE LINE SHAPE ANALYSIS OF A SMALL BARRIER TO INTERNAL ROTATION IN N,N′-DI-TERT.-BUTYLTHIOUREA CHARALYN D. FREEMAN, CHARALYN D. FREEMANSearch for more papers by this authorDONALD L. HOOPER, DONALD L. HOOPERSearch for more papers by this author CHARALYN D. FREEMAN, CHARALYN D. FREEMANSearch for more papers by this authorDONALD L. HOOPER, DONALD L. HOOPERSearch for more papers by this author First published: July 23, 1974 https://doi.org/10.1002/chin.197429087AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue29July 23, 1974 RelatedInformation

Measurement of proton magnetic resonance line shape analysis of a small barrier to internal rotation in N,N'-di-tert-butylthiourea

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMeasurement of proton magnetic resonance line shape analysis of a small barrier to internal rotation in N,N'-di-tert-butylthioureaCharalyn D. Freeman and Donald L. HooperCite this: J. Phys. Chem. 1974, 78, 10, 961–962Publication Date (Print):May 1, 1974Publication History Published online1 May 2002Published inissue 1 May 1974https://doi.org/10.1021/j100603a004RIGHTS & PERMISSIONSArticle Views24Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (270 KB) Get e-Alerts

Proton magnetic resonance line shapes in the titanium and zirconium hydrides

The proton magnetic resonance in the polycrystalline hydrides of titanium and zirconium have been observed and the root mean second moments ( M 2 1 2 ), root mean fourth moments ( M 4 1 4 ), the ratios M 4 1 4 M 2 1 2 , ΔH ms1 2 M 2 1 2 , and ΔH 1 2 ΔH ms1 have been obtained. It has been confirmed that the observed M 4 1 4 M 2 1 4 values of the proton resonance in the nearly stoichiometric titanium hydrides agree well with the theoretical value of O'Reilly and Tsang for a polycrystalline simple cubic lattice. Three theoretical line shapes on the different bases, i.e., the analytical shape by Abragam, the Green's function formalism by Mansfield, and the information theory by Powles and Carazaa, have been compared with the experimental line shapes of the hydrides. The agreements have been found to be satisfactory if the line broadening source is purely a dipolar interaction.

Theoretical Description of the Proton Magnetic Resonance Line Shapes of Ammonium Ions under the Influence of Tunneling

Abstract : A theoretical treatment for the NMR absorption line shape of a tetrahedral group of portons under the influence of tunneling has been developed for the particular case of NH4(+) ions. For the applied field parallel to a twofold axis of the ion the derived line shapes depend on a single splitting parameter J. This is a measure of the tunneling splitting of the torsional ground state in comparison to the dipolar energy of the ion. As J varies from 0 to infinity the calculated line shapes are found to vary between the limiting cases of the distinguishable proton (four spin 1/2) and indistinguishable proton (spin isomeric) situations, respectively. These theoretical line shapes are compared with the observed 'rigid-lattice' line shapes reported for the halides NH4Cl, NH4Br, and NH4I. (Modified author abstract)

On a Proton Magnetic Resonance Study of H2S and H2Se

The proton magnetic resonance line shape and second moment have been studied in H2S and H2Se at 58°K. The observed second moment values indicate that the lattice of H2S and H2Se is essentially rigid at this temperature. The line shapes have been fitted by the method of least squares to a theoretical lineshape function having the intramolecular H–H distance as an adjustable parameter. The H–H distances obtained are 1.883 ± 0.007 Å for H2S and 2.014 ± 0.011 Å for H2Se.

High Dynamic Polarization of Protons

This paper is a detailed study of the dynamic polarization of the protons in the waters of hydration in the crystal ${(\mathrm{N}\mathrm{d},\phantom{\rule{0ex}{0ex}}\mathrm{L}\mathrm{a})}_{2}$${\mathrm{Mg}}_{3}$${(\mathrm{N}{\mathrm{O}}_{3})}_{12}$\ifmmode\cdot\else\textperiodcentered\fi{}24${\mathrm{H}}_{2}$O, which occurs when one saturates a microwave forbidden transition that simultaneously flips a proton and a ${\mathrm{Nd}}^{3+}$ ion. The proton relaxation, as well as the dynamics of the polarization process, is discussed in terms of a phenomenological shell-of-influence model. A polarization apparatus is described for use at frequencies up to 75 kMc/sec and temperatures $1.3lTl4.2$\ifmmode^\circ\else\textdegree\fi{}K. Proton relaxation rates ${{T}_{1p}}^{\ensuremath{-}1}$ are measured over a wide range of fields $H$ and temperatures, and are found to be in agreement with the predicted rate ${{T}_{1p}}^{\ensuremath{-}1}\ensuremath{\approx}{{T}_{1e}}^{\ensuremath{-}1}{(\frac{{g}_{\mathrm{Nd}}\ensuremath{\beta}}{H})}^{2}{〈{r}^{\ensuremath{-}6}〉}_{\mathrm{av}}$ where ${{T}_{1e}}^{\ensuremath{-}1}$ is the relaxation rate for the ${\mathrm{Nd}}^{3+}$ ion, $r$ is the separation between proton and ion, and the average is taken over the shell of influence. At the Nd concentration studied (\ensuremath{\sim}1%), the local fields apparently prevent the free diffusion of spin temperature. Dynamic proton polarization measurements are made over a wide range of frequencies and temperatures: at 75 kMc/sec and 1.5\ifmmode^\circ\else\textdegree\fi{}K a polarization of at least 70% is observed. At these high polarizations, the proton magnetic-resonance line shape changes and a structure appears, due to the freezing-in of the local dipolar fields. At still higher polarizations a local-field computation predicts a series of sharp proton lines, suggesting the possibility of high-resolution nuclear magnetic resonance in solids. The crystal studied is a favorable one for construction of polarized proton targets.

Transient nuclear magnetic resonance signals for liquids with exchanging nuclei

Experimental results are given for both the steady-state proton magnetic resonance line shape and for the echo amplitude modulation pattern for liquid methyl alcohol over a temperature range which includes the collapse of the J multiplet due to increasingly rapid hydroxyl proton exchange. A theory is given for the modulation of the echo amplitude in the presence of exchange by a generalization of Anderson and Weiss's method [9] and also by use of McConnell's equations [10]. An approximate theory is also given which gives considerable insight into the physical meaning of the more complex exact solutions. The value of the approximate method is also illustrated by applying it to the analysis of the collapse of the complex methyl multiplet in NN dimethyl formamide. It is shown that, generally speaking, the echo amplitude modulation measurement, while giving similar results as for the steady-state measurements, have certain advantages both in the determination of coupling constants and exchange correlation tim...

Proton Magnetic Resonance of Solid Sym-Tetrachloro and Tetrabromoethane

The proton magnetic resonance line shapes have been observed in solid sym-tetrachloroethane and sym-tetrabromoethane. The second moments of the absorption lines provide unambiguous assignments of the molecular forms. The results confirm the formation by CHBr2CHBr2 of crystals of either trans- or of gauche-molecules, depending upon thermal treatment, with the trans-crystals stabler at low temperatures. Only the gauche-form of solid CHCl2CHCl2 could be prepared.