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Grimaldo M, Roosen-Runge F, Zhang F, Seydel T, Schreiber F. Diffusion and Dynamics of γ-Globulin in Crowded Aqueous Solutions. J Phys Chem B 2014; 118:7203-9. [DOI: 10.1021/jp504135z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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52
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Armstrong CL, Häussler W, Seydel T, Katsaras J, Rheinstädter MC. Nanosecond lipid dynamics in membranes containing cholesterol. SOFT MATTER 2014; 10:2600-2611. [PMID: 24647350 DOI: 10.1039/c3sm51757h] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Lipid dynamics in the cholesterol-rich (40 mol%) liquid-ordered (lo) phase of dimyristoylphosphatidylcholine membranes were studied using neutron spin-echo and neutron backscattering. Recent theoretical and experimental evidence supports the notion of the liquid-ordered phase in phospholipid membranes as a locally structured liquid, with small ordered 'domains' of a highly dynamic nature in equilibrium with a disordered matrix [S. Meinhardt, R. L. C. Vink and F. Schmid, Proc. Natl. Acad. Sci. U. S. A., 2013, 110(12), 4476-4481, C. L. Armstrong et al., PLoS One, 2013, 8(6), e66162]. This local structure was found to have a pronounced impact on the membranes' dynamical properties. We found that the long-wavelength dynamics in the liquid-ordered phase, associated with the elastic properties of the membranes, were faster by two orders of magnitude as compared to the liquid disordered phase. At the same time, collective nanoscale diffusion was significantly slower. The presence of a soft-mode (a slowing down) in the long-wavelength dispersion relationship suggests an upper size limit for the ordered lipid domain of ≈220 Å. Moreover, from the relaxation rate of the collective lipid diffusion of lipid-lipid distances, the lifetime of these domains was estimated to be about 100 nanoseconds.
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Soraruf D, Roosen-Runge F, Grimaldo M, Zanini F, Schweins R, Seydel T, Zhang F, Roth R, Oettel M, Schreiber F. Protein cluster formation in aqueous solution in the presence of multivalent metal ions--a light scattering study. SOFT MATTER 2014; 10:894-902. [PMID: 24835564 DOI: 10.1039/c3sm52447g] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The formation of protein clusters as precursors for crystallization and phase separation is of fundamental and practical interest in protein science. Using multivalent ions, the strengths of both long-range Coulomb repulsion and short-range attraction can be tuned in protein solutions, representing a well-controlled model system to study static and dynamic properties of clustering during the transition from a charge-stabilized to an aggregate regime. Here, we study compressibility, diffusion, and size of solutes by means of static (SLS) and dynamic light scattering (DLS) in solutions of bovine serum albumin (BSA) and YCl3. For this and comparable systems, an increasing screening and ultimately inversion of the protein surface charge induce a rich phase behavior including reentrant condensation, liquid-liquid phase separation and crystallization, which puts the cluster formation in the context of precursor formation and nucleation of liquid and crystalline phases. We find that, approaching the turbid aggregate regime with increasing salt concentration cs, the diffusion coefficients decrease and the scattered intensity increases by orders of magnitude, evidencing increasing correlation lengths likely associated with clustering. The combination of static and dynamic observations suggests the formation of BSA clusters with a size on the order of 100 nm. The global thermodynamic state seems to be stable over at least several hours. Surprisingly, results on collective diffusion and inverse compressibility from different protein concentrations can be rescaled into master curves as a function of cs/c*, where c* is the critical salt concentration of the transition to the turbid aggregate regime.
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Hill AH, Jacobsen H, Stewart JR, Jiao F, Jensen NP, Holm SL, Mutka H, Seydel T, Harrison A, Lefmann K. Magnetic properties of nano-scale hematite, α-Fe2O3, studied by time-of-flight inelastic neutron spectroscopy. J Chem Phys 2014; 140:044709. [DOI: 10.1063/1.4862235] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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55
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Bordallo HN, Zakharov BA, Boldyreva EV, Johnson MR, Koza MM, Seydel T, Fischer J. Application of Incoherent Inelastic Neutron Scattering in Pharmaceutical Analysis: Relaxation Dynamics in Phenacetin. Mol Pharm 2012; 9:2434-41. [DOI: 10.1021/mp2006032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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56
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Gerstl C, Schneider GJ, Fuxman A, Zamponi M, Frick B, Seydel T, Koza M, Genix AC, Allgaier J, Richter D, Colmenero J, Arbe A. Quasielastic Neutron Scattering Study on the Dynamics of Poly(alkylene oxide)s. Macromolecules 2012. [DOI: 10.1021/ma3003399] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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57
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Hennig M, Frick B, Seydel T. Optimum velocity of a phase-space transformer for cold-neutron backscattering spectroscopy. J Appl Crystallogr 2011. [DOI: 10.1107/s0021889811013227] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cold-neutron backscattering spectrometers are designed for inelastic neutron scattering experiments at a high energy resolution, where 0.5 µeV FWHM can routinely be achieved at the incident wavelength λ ≃ 6.3 Å. The phase-space transformation (PST) technique can be used to enhance the neutron flux at the sample position of such backscattering spectrometers at the expense of an acceptable increase of the beam divergence. Technically, the PST is achieved by a rotating disc carrying mosaic crystals on its circumference. Here a new analytical framework to describe the Bragg reflection of a divergent polychromatic beam from a moving mosaic crystal is discussed. Results obtained using this framework are compared with detailed Monte Carlo numerical simulations. The results presented here provide a deeper understanding of the PST and in particular of the optimum circumferential crystal speed of a PST device.
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Seydel T, Knoll W, Greving I, Dicko C, Koza MM, Krasnov I, Müller M. Increased molecular mobility in humid silk fibers under tensile stress. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:016104. [PMID: 21405741 DOI: 10.1103/physreve.83.016104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Indexed: 05/30/2023]
Abstract
Silk fibers are semicrystalline nanocomposite protein fibers with an extraordinary mechanical toughness that changes with humidity. Diffusive or overdamped motion on a molecular level is absent in dry silkworm silk, but present in humid silk at ambient temperature. This microscopic diffusion distinctly depends on the externally applied macroscopic tensile force. Quasielastic and inelastic neutron-scattering data as a function of humidity and of tensile strain on humid silk fibers support the model that both the adsorbed water and parts of the amorphous polymers participate in diffusive motion and are affected by the tensile force. It is notable that the quasielastic linewidth of humid silk at 100% relative humidity increases significantly with the applied force. The effect of the tensile force is discussed in terms of an increasing alignment of the polymer chains in the amorphous fraction with increasing tensile stress which changes the geometrical restrictions of the diffusive motions.
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Calvo-Almazán I, Seydel T, Fouquet P. Questions arising for future surface diffusion studies using scattering techniques--the case of benzene diffusion on graphite basal plane surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:304014. [PMID: 21399346 DOI: 10.1088/0953-8984/22/30/304014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This paper gives a review of recent work on benzene diffusion on graphitic carbon surfaces using neutron and helium scattering spectroscopy as well as computational modelling. Recent spin-echo spectroscopy measurements have demonstrated that benzene/graphite displays almost perfect Brownian diffusion and that it can be used as a tool to study dynamic friction. Incoherent neutron backscattering measurements, on the other hand, reveal a jump diffusion behaviour, related to the molecular rotational modes of the benzene rings. Molecular dynamics (MD) simulations have delivered a very detailed picture of the adsorbate dynamics. We use this review to illustrate the open questions and possible future directions of this research field.
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Rubio-Retama J, Zafeiropoulos NE, Frick B, Seydel T, López-Cabarcos E. Investigation of the relationship between hydrogen bonds and macroscopic properties in hybrid core-shell gamma-Fe2O3-P(NIPAM-AAS) microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7101-7106. [PMID: 20143864 DOI: 10.1021/la904452c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigate in a hybrid material the interactions existing between magnetic nanoparticles of gamma-Fe(2)O(3) and the polymer matrix constituted by core-shell poly(N-isopropylacrylamide-sodium acrylate) microgels. These interactions provoke the shifting of the microgel volume phase transition to higher temperatures when the amount of gamma-Fe(2)O(3) increases. The study was performed using different techniques such as incoherent quasi-elastic neutron scattering (IQNS), infrared spectroscopy (FTIR-ATR), and dynamic light scattering (DLS). Below the low critical solution temperature (LCST) of the polymer, the IQNS data confirm that the presence of inorganic nanoparticles affects the PNIPAM chain motions. Thus, in the swollen state both the mean-square displacement of the polymer segments and the diffusive motion of the polymer chains decrease as the iron oxide content increases. The FTIR-ATR study indicates that the reduction of vibrational and diffusional motions of the polymer chains is due to the formation of hydrogen bonds between the amide groups of the polymer matrix and the OH groups of the magnetic nanoparticles. The creation of this hybrid complex would explain the reduction of the swelling capacity with increasing the iron content in the microgels. Furthermore, this interaction could also explain the shift of the polymer LCST to higher temperatures as due to the extra energy required by the system to break the hydrogen bonds prior to the PNIPAM collapse.
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Bordallo HN, Boldyreva EV, Fischer J, Koza MM, Seydel T, Minkov VS, Drebushchak VA, Kyriakopoulos A. Observation of subtle dynamic transitions by a combination of neutron scattering, X-ray diffraction and DSC: A case study of the monoclinic l-cysteine. Biophys Chem 2010; 148:34-41. [DOI: 10.1016/j.bpc.2010.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 02/04/2010] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
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Frick B, Mamontov E, Eijck LV, Seydel T. Recent Backscattering Instrument Developments at the ILL and SNS. ACTA ACUST UNITED AC 2010. [DOI: 10.1524/zpch.2010.6091] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
We present new developments in neutron backscattering spectroscopy from two major neutron scattering centers. The first example is the reactor backscattering project IN16B, which is under construction at the Institut Laue-Langevin (ILL), Grenoble, France, the second is the spallation source near-backscattering spectrometer BASIS at the spallation neutron source SNS, Oak Ridge National Laboratory, USA, in operation since 2007. After explaining the energy resolution contributions to neutron backscattering and presenting the current status, we describe the layout, performance and the complementarity of the two most advanced backscattering projects. A few examples should illustrate the status and new experimental possibilities.
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Rheinstädter MC, Das J, Flenner EJ, Brüning B, Seydel T, Kosztin I. Motional coherence in fluid phospholipid membranes. PHYSICAL REVIEW LETTERS 2008; 101:248106. [PMID: 19113677 DOI: 10.1103/physrevlett.101.248106] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Indexed: 05/08/2023]
Abstract
We report a high energy-resolution neutron backscattering study, combined with in situ diffraction, to investigate slow molecular motions on nanosecond time scales in the fluid phase of phospholipid bilayers of 1,2-dimyristoyl-sn-glycero-3-phoshatidylcholine. A cooperative structural relaxation process was observed. From the in-plane scattering vector dependence of the relaxation rates in hydrogenated and deuterated samples, combined with results from a 0.1 micros long all-atom molecular dynamics simulation, it is concluded that correlated dynamics in lipid membranes occurs over several lipid distances, spanning a time interval from pico- to nanoseconds.
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Seydel T, Wiegart L, Juranyi F, Struth B, Schober H. Unaffected microscopic dynamics of macroscopically arrested water in dilute clay gels. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:061403. [PMID: 19256837 DOI: 10.1103/physreve.78.061403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Indexed: 05/27/2023]
Abstract
Adequate clay minerals considerably affect the macroscopic mechanical behavior of water even at concentrations of a few percent. Thus when 2 wt. % laponite clay mineral nanoparticles are added to water, the resulting colloidal suspension after some time takes on the semisolid characteristics of a jellylike material at room temperature. Cold neutron time-of-flight spectroscopy data are in agreement with the assumption that notwithstanding this macroscopic change, the mobility of the water molecules on intermolecular and intramolecular length scales remains largely unaffected. This observation is discussed in the context of the properties and the role of water in different more or less dilute ionic environments. The result contributes to the ongoing debate of the properties and role of water in living cells.
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Rubio Retama J, Frick B, Seydel T, Stamm M, Fernandez Barbero A, López Cabarcos E. Polymer Chain Dynamics of Core−Shell Thermosensitive Microgels. Macromolecules 2008. [DOI: 10.1021/ma800668t] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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66
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Bordallo HN, Frick B, Schober H, Seydel T. Primary spectrometer neutron optics simulations for a new cold neutron backscattering spectrometer. JOURNAL OF NEUTRON RESEARCH 2008. [DOI: 10.1080/10238160802401344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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67
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Krasnov I, Diddens I, Hauptmann N, Helms G, Ogurreck M, Seydel T, Funari SS, Müller M. Mechanical properties of silk: interplay of deformation on macroscopic and molecular length scales. PHYSICAL REVIEW LETTERS 2008; 100:048104. [PMID: 18352338 DOI: 10.1103/physrevlett.100.048104] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Indexed: 05/26/2023]
Abstract
Using an in situ combination of tensile tests and x-ray diffraction, we have determined the mechanical properties of both the crystalline and the disordered phase of the biological nanocomposite silk by adapting a model from linear viscoelastic theory to the semicrystalline morphology of silk. We observe a strong interplay between morphology and mechanical properties. Silk's high extensibility results principally from the disordered phase; however, the crystals are also elastically deformed.
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Hüller A, Prager M, Press W, Seydel T. Phase III of solid methane: The orientational potential and rotational tunneling. J Chem Phys 2008; 128:034503. [DOI: 10.1063/1.2822293] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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69
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Bordallo HN, Argyriou DN, Barthès M, Kalceff W, Rols S, Herwig KW, Fehr C, Juranyi F, Seydel T. Hydrogen in N-Methylacetamide: Positions and Dynamics of the Hydrogen Atoms Using Neutron Scattering. J Phys Chem B 2007; 111:7725-34. [PMID: 17571870 DOI: 10.1021/jp068528z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work reports neutron diffraction and incoherent neutron scattering experiments on N-methylacetamide (NMA), which can be considered the model building block for the peptide linkage of polypeptides and proteins. Using the neutron data, we have been able to associate the onset of a striking negative thermal expansion (NTE) along the a-axis with a dynamical transition around 230 K, consistent with our calorimetric experiments. Observation of the NTE raises the question of possible proton transfer in NMA, which, from our data alone, still cannot be settled. We can only speculate that intermolecular repulsive forces increase as the O...H distance decreases upon cooling, and that around 230 K the lattice relaxes without observation of an actual proton transfer. However, the existence of a nonharmonic potential, reflected by the behavior of the phonon vibrations together with the observation of NTE, could be justified by the "vibrational" polaron theory in which a dynamic localization of the vibrational energy is created by coupling an internal molecular mode to a lattice phonon. More generally, this work shows that neutron powder diffraction techniques can be very powerful for investigating structural deformations in small peptide systems.
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Seydel T, Kölln K, Krasnov I, Diddens I, Hauptmann N, Helms G, Ogurreck M, Kang SG, Koza MM, Müller M. Silkworm Silk under Tensile Strain Investigated by Synchrotron X-ray Diffraction and Neutron Spectroscopy. Macromolecules 2007. [DOI: 10.1021/ma0624189] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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71
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Rheinstädter MC, Seydel T, Salditt T. Nanosecond molecular relaxations in lipid bilayers studied by high energy-resolution neutron scattering and in situ diffraction. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:011907. [PMID: 17358184 DOI: 10.1103/physreve.75.011907] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Indexed: 05/14/2023]
Abstract
We report a high energy-resolution neutron backscattering study to investigate slow motions on nanosecond time scales in highly oriented solid-supported phospholipid bilayers of the model system deuterated 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine, hydrated with heavy water. Wave-vector-resolved quasielastic neutron scattering is used to determine relaxation times tau , which can be associated with different molecular components, i.e., the lipid acyl chains and the interstitial water molecules in the different phases of the model membrane system. The inelastic data are complemented by both energy-resolved and energy-integrated in situ diffraction. From a combined analysis of the inelastic data in the energy and time domains, the corresponding character of the relaxation, i.e., the exponent of the exponential decay, is also determined. From this analysis we quantify two relaxation processes. We associate the fast relaxation with translational diffusion of lipid and water molecules while the slow process likely stems from collective dynamics.
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Prager M, Pietraszko A, Sobczyk L, Pawlukojć A, Grech E, Seydel T, Wischnewski A, Zamponi M. X-ray diffraction and inelastic neutron scattering study of 1:1 tetramethylpyrazine chloranilic acid complex: temperature, isotope, and pressure effects. J Chem Phys 2006; 125:194525. [PMID: 17129141 DOI: 10.1063/1.2358347] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The x-ray diffraction studies of the title complex were carried out at room temperature and 14 K for H/D (in hydrogen bridge) isotopomers. At 82 K a phase transition takes place leading to a doubling of unit cells and alternation of the hydrogen bond lengths linking tetramethylpyrazine (TMP) and chloranilic acid molecules. A marked H/D isotope effect on these lengths was found at room temperature. The elongation is much smaller at 14 K. The infrared isotopic ratio for O-H(D)...N bands equals to 1.33. The four tunnel splittings of methyl librational ground states of the protonated complex required by the structure are determined at a temperature T=4.2 K up to pressures P=4.7 kbars by high resolution neutron spectroscopy. The tunnel mode at 20.6 microeV at ambient pressure shifts smoothly to 12.2 microeV at P=3.4 kbars. This is attributed to an increase of the strength of the rotational potential proportional to r(-5.6). The three other tunnel peaks show no or weak shifts only. The increasing interaction with diminishing intermolecular distances is assumed to be compensated by a charge transfer between the constituents of deltae/e approximately 0.02 kbar(-1). The phase transition observed between 3.4 and 4.7 kbars leads to increased symmetry with only two more intense tunneling bands. In the isotopomer with deuterated hydrogen bonds and P=1 bar all tunnel intensities become equal in consistency with the low temperature crystal structure. The effect of charge transfer is confirmed by a weakening of rotational potentials for those methyl groups whose tunnel splittings were independent of pressure. Density functional theory calculations for the model TMP.(HF)2 complex and fully ionized molecule TMP+ point out that the intramolecular rotational potential of methyl groups is weaker in the charged species. They do not allow for the unequivocal conclusions about the role of the intermolecular charge transfer effect on the torsional frequencies.
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Rheinstädter MC, Seydel T, Farago B, Salditt T. Probing dynamics at interfaces: options for neutron and X-ray spectroscopy. JOURNAL OF NEUTRON RESEARCH 2006. [DOI: 10.1080/10238160600975424] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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74
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Madsen A, Seydel T, Tolan M, Grübel G. Grazing-incidence scattering of coherent X-rays from a liquid surface. JOURNAL OF SYNCHROTRON RADIATION 2005; 12:786-94. [PMID: 16239749 DOI: 10.1107/s0909049505022065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Accepted: 07/08/2005] [Indexed: 05/04/2023]
Abstract
The scattering image produced by coherent X-rays appears grainy and is denoted a speckle pattern. An analysis of the static and time-dependent properties of a speckle pattern generated by scattering of a partially coherent synchrotron beam from a liquid surface is given here. Unique surface sensitivity is achieved by applying the X-rays under a grazing angle of incidence. The observed contrast of the speckle pattern depends on the momentum transfer parallel to the surface, unlike the case of transmission small-angle X-ray scattering (SAXS), where essentially no q-dependence of the contrast has been observed. The appearance of the speckles and the contrast of the image can be understood qualitatively by use of geometrical arguments and by the fact that liquid surfaces are extremely flat.
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Sapede D, Seydel T, Forsyth VT, Koza MM, Schweins R, Vollrath F, Riekel C. Nanofibrillar Structure and Molecular Mobility in Spider Dragline Silk. Macromolecules 2005. [DOI: 10.1021/ma0507995] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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