| | 41 | Author
| MichaelC. Böhm, Thomas Schedel-Niedrig, Hartmut Werner, Robert Schlögl, Joachim Schulte, Johannes Schiitt | Requires cookie* | | | Title
| Electronic Structure of the C 6Ü Fragment in Alkali-and Alkaline-earth-doped Fullerides  | | | | Abstract
| The electronic structure of the C50 fragment in alkali-and alkaline-earth-doped fullerides is studied theoretically. With increasing metal-to-C 60 charge transfer (CT) the n electronic properties of the soccerball are changed. In the undoped solid and for not too high a concentration of doping atoms the hexagon-hexagon (6-6) bonds show sizeable double bond character while the hexagon-pentagon (6-5) bonds are essentially of single bond type. In systems with a high concentration of doping atoms this relative ordering is changed. Now the 6-5 bonds have partial double bond character and the 6-6 bonds are essentially single bonds. The high ability of the C 60 unit to accomodate excess electrons prevents any sizeable weakening of the overall n bonding in systems with up to 12 excess electrons on the soccerball. A crystal orbital (CO) formalism on the basis of an INDO (intermediate neglect of differential overlap) Hamiltonian has been employed to derive solid state results for potassium-and barium-doped C 60 fullerides. For both types of doping atoms an incomplete metal-to-C 60 CT is predicted. In the potassium-doped fullerides the magnitude of the CT depends on the interstitial site of the dopant. The solid state data have been supplemented by INDO and ab initio calculations on molecular C 60 , and C^, 2 , -. The calculated bondlength alternation in the neutral molecule is changed in C 6 ö~ where the length of the 6-6 bonds exceeds the length of the 6-5 bonds. The geometries of the three molecular species have been optimized with a 3-21 G* basis. The theoretically derived modification of the C 60 (7r) electronic structure as a function of the electron count is explained microscopically in the framework of two quantum statistics accessible for n electronic ensembles. In the 7r ensemble of the C W) fragment so-called hard core bosonic properties are maximized where the Pauli antisymmetry principle has the character of a hidden variable only. Here the electronic degrees of freedom are attenuated only by the Pauli exclusion principle. This behaviour leads to the changes in the ir electronic structure mentioned above. | | | |
Reference
| Z. Naturforsch. 51a, 283—298 (1996); received February 27 1996 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0283.pdf | | | | Identifier
| ZNA-1996-51a-0283 | | | | Volume
| 51 | |
| 42 | Author
| K. Voges, J. Gripp, H. Hartwig, H. Dreizler | Requires cookie* | | | Title
| Analysis of Torsion in a Three-Top Molecule. Torsional Barrier and Moment of Inertia of Trimethyl Ethynyl Germane | | | | Abstract
| Internal rotation effects for a large number of molecules containing one or two symmetric internal rotors have been investigated using microwave spectroscopy. The high resolution of molecular beam Fourier transform microwave spectroscopy revealed now the internal rotation fine structure in the rotational spectrum of trimethyl ethynyl germane, (CH 3) 3 GeC=CH. After assigning the rotational transition J = 1 — 0 in the vibrational and torsional ground state to the symmetry species of the molecular symmetry group G I62 , the torsional barrier V3 and the rotational constant Bo could be determined to (4.5±0.2) kJ/mofand (1823.370±0.010) MHz, respectively. spectrometer. It should be pointed out, that for sym-metric three top molecules a torsion fine structure can be observed. This is different for symmetric rotors like CH 3 SiH 3 . Group theory was used to assign the torsional line pattern of trimethyl ethynyl germane. Thereby we noticed degeneracies reducing the num-ber of components in the torsional line pattern to six. Experimental Methods Sample preparation Trimethyl ethynyl germane has been prepared ac-cording to the method given by MacLean and Sacher [2]. From 15 g of a commercially available slurry of 18% sodium acetylide in xylene the liquid phase was distilled off and the solid residual was dried at 80 °C in vacuo. Subsequently 50 ml nitrobenzene, dried over calcium chloride, and 4 g trimethyl chlorogermane have been added in a dry inert gas flow. The mix-ture has been stirred over night under exclusion of air and subsequently warmed up to 50 °C. The volatile reaction products could easily be separated from the nitrobenzene by a vacuum distillation at room tem-perature and yielded about 3 ml trimethyl ethynyl germane in a purity of 95% (checked by gas chro-matography). Microwave measurement The used MB-FTMW spectrometer contains a tun-able confocal microwave cavity, which is mounted Reprint requests to Prof. Dr. H. Dreizler. | | | |
Reference
| Z. Naturforsch. 51a, 299—305 (1996); received February 13 1995 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0299.pdf | | | | Identifier
| ZNA-1996-51a-0299 | | | | Volume
| 51 | |
| 43 | Author
| T. Brückert, A. Würflinger | Requires cookie* | | | Title
| Dielectric Studies of trans,trans-4'-/i-Pentyl-bicyclohexyl-4- carbonitrile (5 CCH) under High Pressure | | | | Abstract
| Dielectric studies on the static and complex permittivity have been performed on trans,trans-4'-«-pentyl-bicyclohexyl-4-carbonitrile (5 CCH) in the pressure range 0.1-200 MPa, the frequency range lkHz-13MHz and the temperature range 300-390 K. Phase transitions between the isotropic, nematic, smectic B (metastable), and crystalline state have been recorded as steps in the static permittivity. Thus the phase diagram of 5 CCH was established. In particular the slow relaxation process in the nematic and smectic phase has been investigated. The dielectric relaxation time T|| increases by a constant factor of 210 on passing the nematic-smectic B phase transition. From the pressure and temperature dependences of x we have calculated the activation volumes (A* K/cm 3 moP 1 = 88-65 (nematick = 70-45 (smectic) and « 32 for the isotropic phase) and activation enthalpies (A*H/ki mol" 1 = 76-60 (nematic), % 60 (smectic) and % 37 for the isotropic phase), respectively, which are compared with previous results on similar homologous series. The activation parameters increase significantly, when the rigid phenyl ring is replaced by the more flexible cyclohexyl ring. | | | |
Reference
| Z. Naturforsch. 51a, 306—312 (1996); received March 5 1996 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0306.pdf | | | | Identifier
| ZNA-1996-51a-0306 | | | | Volume
| 51 | |
| 45 | Author
| R. E. Youngman, U. Werner-Zwanziger, J. W. Zwanziger | Requires cookie* | | | Title
| A Comparison of Strategies for Obtaining High-Resolution NMR Spectra of Quadrupolar Nuclei | | | | Abstract
| A comparison of high-resolution NMR methods for quadrupolar nuclei is presented. The samples studied are pure and modified boron oxide glasses, and the boron NMR spectra are recorded using three different experiments capable of high resolution: Double Rotation, Dynamic Angle Spinning, and Multiple-Quantum Magic Angle Spinning. Resolution of the similar ring and nonring boron sites in these glasses, in the presence of disorder, provides a realistic study of the strengths and limitations of these experiments. Conclusions about the relative applicability of these experiments in different situations are presented. | | | |
Reference
| Z. Naturforsch. 51a, 321—329 (1996); received October 10 1995 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0321.pdf | | | | Identifier
| ZNA-1996-51a-0321 | | | | Volume
| 51 | |
| 46 | Author
| Rainer Kimmich | Requires cookie* | | | Title
| Multidimensional NQR: Imaging and Exchange Spectroscopy | | | | Abstract
| In this context a "dimension" can be of a spatial or of a spectroscopic nature. In the last two decades, multidimensional nuclear magnetic resonance and imaging have proven to be most useful tools for the investigation of materials. It turned out that some of these measuring principles can be applied to zero-field NQR as well. The purpose of this presentation is to elucidate two-dimensional exchange spectroscopy and imaging procedures suitable for NQR and to outline potential applications. | | | |
Reference
| Z. Naturforsch. 51a, 330—336 (1996); received January 22 1996 | | | |
Published
| 1996 | | | |
Keywords
| NQR, imaging, 2D exchange spectroscopy, pressure, temperature | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0330.pdf | | | | Identifier
| ZNA-1996-51a-0330 | | | | Volume
| 51 | |
| 47 | Author
| Mariusz Maćkowiak, Piotr Kątowski | Requires cookie* | | | Title
| Enhanced Information Recovery in 2D On-and Off-Resonance Nutation NQR using the Maximum Entropy Method | | | | Abstract
| Two-dimensional zero-field nutation NQR spectroscopy has been used to determine the full quadrupolar tensor of spin —3/2 nuclei in serveral molecular crystals containing the 35 C1 and 75 As nuclei. The problems of reconstructing 2D-nutation NQR spectra using conventional methods and the advantages of using implementation of the maximum entropy method (MEM) are analyzed. It is shown that the replacement of conventional Fourier transform by an alternative data processing by MEM in 2D NQR spectroscopy leads to sensitivity improvement, reduction of instrumental artefacts and truncation errors, shortened data acquisition times and suppression of noise, while at the same time increasing the resolution. The effects of off-resonance irradiation in nutation exper-iments are demonstrated both experimentally and theoretically. It is shown that off-resonance nutation spectroscopy is a useful extension of the conventional on-resonance experiments, thus facilitating the determination of asymmetry parameters in multiple spectrum. The theoretical de-scription of the off-resonance effects in 2D nutation NQR spectroscopy is given, and general exact formulas for the asymmetry parameter are obtained. In off-resonance conditions, the resolution of the nutation NQR spectrum decreases with the spectrometer offset. However, an enhanced resolu-tion can be achieved by using the maximum entropy method in 2D-data reconstruction. Key words: Nuclear quadrupole resonance, 2D nutation spectroscopy, maximum entropy method, electric field gradient tensor. | | | |
Reference
| Z. Naturforsch. 51a, 337—347 (1996); received January 22 1996 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0337.pdf | | | | Identifier
| ZNA-1996-51a-0337 | | | | Volume
| 51 | |
| 48 | Author
| David Stephenson, JohnA S Smith | Requires cookie* | | | Title
| Zeeman Transitions in Low Magnetic Field: Dependence of Line Shapes on the Asymmetry Parameter for Spin >3/2 Systems | | | | Abstract
| Transitions between the Zeeman levels of spin 3/2 systems have been detected in low magnetic fields (ca. 25 mT) via the dynamic solid effect. Transitions are detected at frequencies v p ± v Q , where Vq corresponds to the Zeeman splitting of the ± 1 /2 and/or the ± 3/2 levels in the small applied field, and v p is the proton NMR frequency. Using this approach, the line shape for polycrystalline samples can be recorded with a good signal-to-noise ratio despite the low frequencies involved. Computer calculated line shapes are also presented, which show that the asymmetry parameter can be obtained from the experimental spectra. | | | |
Reference
| Z. Naturforsch. 51a, 348—352 (1996); received October 20 1995 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0348.pdf | | | | Identifier
| ZNA-1996-51a-0348 | | | | Volume
| 51 | |
| 49 | Author
| H. Robert, D. J. Pusiol | Requires cookie* | | | Title
| Fast p-NQR Imaging with Slice Selection | | | | Abstract
| A combination of a new pulse sequence allowing fast data acquisition in the rotating frame version of NQR (p-NQRI) together with a method for slice selection, is reported. The procedure allows us to record the magnetization evolution during its motion in the rotating frame. At the same time a zero-crossing external magnetic field gradient is applied in order to select a determined slice of the object to be imaged. The experiments reported are the first steps toward a fast tridimensional /o-NQRI; even more, as the spectroscopic information is preserved during the spatial encoding procedure, it could be considered as a 3D spatially resolved NQR spectroscopy technique. | | | |
Reference
| Z. Naturforsch. 51a, 353—356 (1996); received November 20 1995 | | | |
Published
| 1996 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0353.pdf | | | | Identifier
| ZNA-1996-51a-0353 | | | | Volume
| 51 | |
| 50 | Author
| B. Bandyopadhyay, G. B. Furman, S. D. Goren, C. Korn, A. L. Shames | Requires cookie* | | | Title
| One Pulse Spin-locking in NQR | | | | Abstract
| The response of a quadrupolar spin system in zero applied magnetic field to a long if pulse, for both single crystal and polycrystalline samples possessing broad Lorentzian-shaped resonance lines has been studied. The dependencies of magnetization on frequency offset, linewidth and power are investigated both theoretically and experimentally. The problem of the effective field direction in both single crystal and polycrystalline samples is also discussed. For a polycrystalline cuprous oxide (Cu 2 0) sample it is observed that the magnetization after a long pulse in on-resonance condition does not become zero for time t P T 2 , in agreement with theoretical results. It has also been shown that the magnetization increases with increase in the width of the resonance line as well as with the decrease in the excitation power. | | | |
Reference
| Z. Naturforsch. 51a, 357—362 (1996); received December 12 1995 | | | |
Published
| 1996 | | | |
Keywords
| NQR, one pulse spin-locking, Cu 2 0 | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0357.pdf | | | | Identifier
| ZNA-1996-51a-0357 | | | | Volume
| 51 | |
| 51 | Author
| Nicolai Sinyavsky, Michal Ostafin, Mariusz Maćkowiak | Requires cookie* | | | Title
| Rapid Measurement of Nutation NQR Spectra in Powders Using an RF Pulse Train | | | | Abstract
| The method of two-dimensional nutation NQR spectroscopy, introduced by Harbison in 1989, has been successfully used for determining of the asymmetry parameter of the EFG tensor for spin-3/2 nuclei in both powdered and monocrystal samples in the absence of an external magnetic field. The inconvenience inherent in the method, however, is the long time required, because data acquisition must be repeated for various RF pulse lengths. We discuss a method to reduce the time of the nutation experiment by using a sequence of identical short RF pulses of length r w and distance t. It is shown that for an NQR frequency co 0 , frequency offset Aco, and pulse parameters satisfying the relation co 0 1 -I-Aco t w = 2 n k (k = 1, 2, 3,..., n) a synchronism of pulse action takes place and the nutation interferogram can be measured "stroboscopically" between the pulses. The maximum time saving factor that can be obtained as compared to the conventional nutation experiment is of the order of the number of pulses used in a pulse train. The method has been successfully applied for determination of the asymmetry parameter for one of the two 35 C1 sites in polycrystalline 2,4,6-trichloro-l,3,5-triazine (cyanuric chloride). | | | |
Reference
| Z. Naturforsch. 51a, 363—367 (1996); received February 13 1996 | | | |
Published
| 1996 | | | |
Keywords
| Nuclear quadrupole resonance, Two-dimensional nutation spectroscopy, Asymmetry parameter | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0363.pdf | | | | Identifier
| ZNA-1996-51a-0363 | | | | Volume
| 51 | |
| 52 | Author
| DesmondC. Cook | Requires cookie* | | | Title
| Measurement of Nuclear Quadrupole Interactions using Mössbauer Spectroscopy | | | | Abstract
| Mössbauer spectroscopy is a useful probe for investigating nuclear quadrupole interactions. It enables the magnitude, sign and asymmetry of the electric quadrupole coupling constant to be determined. It is especially important for its ability to measure these parameters for excited nuclear states. The Mössbauer effect is used to measure excited state quadrupole moments in materials whose electric field gradient (EFG) is known. More commonly however, it is used to determine the EFG from which atomic bonding and electronic structure are determined. The technique also allows temperature dependent orientation of sublattice magnetization to be measured using the direction of the electric quadrupole coupling as a reference. | | | |
Reference
| Z. Naturforsch. 51a, 368—372 (1996); received November 20 1995 | | | |
Published
| 1996 | | | |
Keywords
| Mössbauer Effect, Electric Field Gradient, Quadrupole Interaction | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0368.pdf | | | | Identifier
| ZNA-1996-51a-0368 | | | | Volume
| 51 | |
| 53 | Author
| W. J. Bresser, J. Wells, M. Zhang, P. Boolchand | Requires cookie* | | | Title
| Molecular Origin of Glass Forming Tendency in Ternary Te-Se-Br(Cl) Chalcohalide Glasses | | | | Abstract
| Bulk glasses of Te 3 _-Se-(CI or Br) 2+V , the composition spanning the glass forming range, were characterized by differential scanning calorimetry, l2r, Te absorption, and 129 I emission Mössbauer spectroscopy. The results reveal that the stoichiometric glasses Te 3 (Cl or Br) 2 consists of c-Te 3 Cl 2 -like chain fragments about 1.5 nm long and terminated by one-fold coordinated halogen atoms. The 12:i Te electric hyperfine structure results reveal that Te replacement by Se (z =/ 0) leads to preferential occupancy at those Te sites in the chains that are two-fold coordinated, and in a rather striking fashion demonstrate that the average length of the chain fragments remains independent of Se concentration. Halogen atoms in the glasses act as chain terminators, and also bond to Te-sites in the chains to produce four-fold coordinated sites. The low glass transition temperatures (7g ~ 70 -90°C), the low average coordination number of the proposed chain-fragments, along with the hyperfine structure results, suggest that the extensive glass forming tendency in the chalcohalides derives from the floppiness of the chain-fragments. | | | |
Reference
| Z. Naturforsch. 51a, 373—380 (1996); received January 5 1996 | | | |
Published
| 1996 | | | |
Keywords
| ^Te Absorption Mössbauer Spectroscopy, 129 I Emission Mössbauer Spectroscopy, Chalcohalide Glasses, Molecular Structure, Glass Formation | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0373.pdf | | | | Identifier
| ZNA-1996-51a-0373 | | | | Volume
| 51 | |
| 55 | Author
| M. Sorescu, E. T. Knobbe | Requires cookie* | | | Title
| Mössbauer Spectroscopy Evidence for Phase Selectivity in Excimer Laser Induced Amorphization of Thermally Annealed FeCoBSi Metallic Glass | | | | Abstract
| Pulsed excimer laser irradiation effects (/. = 308 nm, T = 10 ns, w = 3 J/cm 2 , N = 2 laser pulses/ spot, repetition rate 1 Hz) on the magnetic properties and phase composition of thermally annealed Fe 66 Co 18 B 15 Si 1 metallic glass have been studied by transmission and conversion electron Möss-bauer spectroscopy (CEMS). Radiation-driven surface modifications were examined by scanning electron microscopy (SEM). Excimer laser induced amorphization was observed in partially crystal-lized Fe 66 Co 18 B 15 Si 1 samples (7" A = 648 K, r A = 1 hour) and was found to be accompanied by the development of laser-induced magnetic anisotropy. In totally crystallized Fe^Co^B^Si! speci-mens (T A = 723 K, = 1 hour), the effect of excimer laser induced amorphization exhibited phase selectivity with respect to the crystalline components of the alloy system. When compared to bulk data, a different behavior of the surface magnetic texture and relative abundance of alloy phases was observed. The laser-induced phase transformation of thermally annealed Fe 66 Co 18 B 15 Si 1 specimens was shown to consist of partial amorphization and surface oxidation of the irradiated material. | | | |
Reference
| Z. Naturforsch. 51a, 389—395 (1996); received February 3 1996 | | | |
Published
| 1996 | | | |
Keywords
| Metallic glasses, Laser processing, Phase transformations, Magnetic properties, Möss-bauer spectroscopy | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0389.pdf | | | | Identifier
| ZNA-1996-51a-0389 | | | | Volume
| 51 | |
| 56 | Author
| T. Butz | Requires cookie* | | | Title
| Nuclear Quadrupole Interactions Studied by Time Differential Perturbed Angular Correlations of y-Rays | | | | Abstract
| This paper gives an elementary introduction to time differential perturbed angular correlation of y-rays emitted from excited nuclei with particular reference to nuclear quadrupole interactions. We start with a comparison to other techniques such as nuclear quadrupole resonance and the Mössbauer effect, quote all necessary formulae, describe a typical spectrometer, list suitable iso-topes, and finally give some examples for modern applications. | | | |
Reference
| Z. Naturforsch. 51a, 396—410 (1996); received December 12 1995 | | | |
Published
| 1996 | | | |
Keywords
| Nuclear quadrupole interactions, Time differential perturbed angular correlations (TDPAC), TDPAC: theory, spectrometers, isotopes, Mercury compounds, Tungsten compounds | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0396.pdf | | | | Identifier
| ZNA-1996-51a-0396 | | | | Volume
| 51 | |
| 57 | Author
| GaryL. Catchen, EdwardF. Hollinger, ToddM. Rearick | Requires cookie* | | | Title
| Characterizing Phase Transitions in the Perovskites PbTi0 3 and BaTi0 3 Using Perturbed-Angular-Correlation Spectroscopy | | | | Abstract
| Perturbed-angular-correlation (PAC) spectroscopy was used to measure in ceramic samples of PbTi0 3 and BaTi0 3 the temperature dependence of the Ti-site electric-field gradients (EFGs) at temperatures very close to the ferroelectric-to-paraelectric transition temperatures T c . The samples were doped with small amounts of Hf that carried the 181 Hf — l8l Ta probe radioactivity. A high-frequency nuclear quadrupole interaction that decreases very little as the temperature approaches T c , characterizes the PbTi0 3 transition. The tetragonal and cubic phases for PbTi0 3 appear to coexist over a temperature interval of 8 ± 1 K, and the transition shows a thermal hysteresis of about 4 K. In contrast, a lower-frequency interaction that decreases rapidly as temperature approaches T c , characterizes the BaTiO, transition. Both phases of BaTi0 3 appear to coexist over an interval of about 2 K, and the thermal hysteresis is about 1 K. At temperatures above T c , both PbTi0 3 and BaTi0 3 show weak, non-vanishing Ti-site EFGs. Although, for BaTi0 3 , this effect limits the accuracy with which critical effects can be measured, we estimate a power-law exponent ß = 0.21 ± 0.05, which most likely is somewhat lower in magnitude than the actual critical exponent. For the explanation of our observations we assume the existence of a distribution of T c -values. This distribution would arise because the crystals could have spatially non-uniform distributions of nucleation sites, which for PbTi0 3 and BaTi0 3 could be point defects. | | | |
Reference
| Z. Naturforsch. 51a, 411—421 (1996); received November 20 1995 | | | |
Published
| 1996 | | | |
Keywords
| Ferroelectric, perovskite, nuclear electric-quadrupole, perturbed-angular-correlations, phase transition | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0411.pdf | | | | Identifier
| ZNA-1996-51a-0411 | | | | Volume
| 51 | |
| 58 | Author
| Lars Hemmingsen, Steen Hansen | Requires cookie* | | | Title
| Bayes' Theorem Applied to the Selection of Models in PAC | | | | Abstract
| Using Bayes' formula, the parameters in a given model fitting data from perturbed angular correlation of y-rays (PAC) experiments are all integrated out, giving as the result the total proba-bility for the model. Experimental examples are given from PAC for models containing one and two nuclear quadrupole interactions, respectively. It is shown how the Bayesian formulation leads to a quantification of the probability of the correctness of the models. Furthermore, this method leads to a transparent and intuitively appealing criterion for model selection. Examples are given using PAC measurements on two proteins: liver alcohol dehydrogenase and azurin. | | | |
Reference
| Z. Naturforsch. 51a, 422—426 (1996); received September 26 1995 | | | |
Published
| 1996 | | | |
Keywords
| PAC, Bayesian methods, model selection | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0422.pdf | | | | Identifier
| ZNA-1996-51a-0422 | | | | Volume
| 51 | |
| 59 | Author
| W. Tröger, C. Lippert, P. Schmidt, U. Schmidt, T. Butz, R. Hoffmann, M. Zeppezauer | Requires cookie* | | | Title
| Hg-Coordination Studies of Cysteine Containing Oligopeptides * and the ISOLDE Collaboration 0 | | | | Abstract
| In order to study the interaction of cysteine containing peptide chains with Hg(II) the nuclear quadrupole interaction (NQI) of 199m Hg in the Hg complex of the oligopeptide Alanine-Alanine-Cysteine-Alanine-Alanine (AACAA) was determined by time differential perturbed angular correla-tion. Different 199m Hg-NQI's for free and resin-bound AACAA were obtained. Furthermore, the 199m Hg-NQI's are influenced by the Hg:AACAA stoichiometry. | | | |
Reference
| Z. Naturforsch. 51a, 427—430 (1996); received October 20 1995 | | | |
Published
| 1996 | | | |
Keywords
| TDPAC, Nuclear quadrupole interaction, Oligopeptides, Hg-Coordination | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0427.pdf | | | | Identifier
| ZNA-1996-51a-0427 | | | | Volume
| 51 | |
| 60 | Author
| W. Tröger, C. Lippert, T. Butz, K. Sigfridsson, Ö. Hansson, E. Mclaughlin, R. Bauer, E. Danielsen, L. Hemmingsen, M. J. Bjerrum | Requires cookie* | | | Title
| Small Scale Intramolecular Flexibility in lllm Cd-Plastocyanin | | | | Abstract
| The effect of mutations in the vicinity of the putative electron transfer path on the metal center of the electron transfer protein plastocyanin (spinacea) is investigated by monitoring the nuclear quadrupole interaction of 1Um Cd in Cd-derivatives of the protein via time differential perturbed angular correlation. The spectra for the wild type protein and the mutants were rather similar. All spectra exhibit a peculiar line profile which points towards a small scale intramolecular flexibility of the metal center. | | | |
Reference
| Z. Naturforsch. 51a, 431—436 (1996); received October 20 1995 | | | |
Published
| 1996 | | | |
Keywords
| TDPAC, Nuclear quadrupole interaction, lllm Cd-Plastocyanin, flexibility | | | |
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| default:Reihe_A/51/ZNA-1996-51a-0431.pdf | | | | Identifier
| ZNA-1996-51a-0431 | | | | Volume
| 51 | |
|
