bluuebunny/crossref_metadata_2025 huggingface dataset:
Association in Molten Salts and Mobility Isotherms showing the Chemla Effect
Authors: Klemm Alfred , Schäfer Lutz
Published: February 2015

In 1984 a model for additive binary molten salt mixtures had been proposed that allowed for a qualitative understanding of the occurence of the Chemla effect (equal internal mobilities at a certain mixing ratio of the salts). In that model the presence of three ions (1,2 and 3) and two neutral molecules (4 and 5) consisting of two ions is assumed, and the ratios K1 = x4 / x1x3 and K2 = X5 / X2X3 of their mole fractions are assumed to be independent of the mixing ratio of the salts. In the present paper, that model is compared with recent experimental results on the system (Li, Cs)Cl obtained in Japan. The comparison shows that the model is too simple for a quantitative description of systems showing the Chemla effect. Rather a dependence of K1 and K2 on the mixing ratio of the salts must be assumed.
A Unified Mechanism for the Production of ZEKE States
Authors: Held A. , Baranov L. Ya. , Selzle H. L. , Schlag E. W.
Published: February 2015

ZEKE states are highly stabilized Rydberg states which exist below each ionic eigenstate of a molecular system even high up into the continuum. The stability and neutrality of these states is the basis on which the high resolution ZEKE technique for the study of molecular ions is built upon. A new mechanism is proposed for the production of ZEKE states from optically accessible, relatively short lived Rydberg states. The mechanism is based on experimental results for a range of fields and ion concentrations. The experiments were performed with pulsed and static electric fields of different magnitudes at various ion concentrations.
The Rationale of Trouton's Rule and of the Trouton-Hildebrand-Everett Rule
Authors: Logan S. R.
Published: February 2015

In seeking a rational basis for the general rules regarding the enthalpy of vaporisation of a liquid, it is shown that whereas Trouton's Rule is consistent with the assumption that the effective molar volume, v, for translational motion in the liquid is a constant fraction (2 x 10-5) of the molar volume of vapour at 1 atm, the rather better approximation of Trouton, Hildebrand and Everett (THE), which corrects for the effects of varying molecular density in the vapour, re-quires that v be 1.5 cm3 mol-1 for all substances. The introduction of the apparently more reasonable assumption that v is a constant fraction of the molar volume of the liquid, is shown to lead to an expression exhibiting much poorer cor-relation. It thus offers no improvement to Trouton's rule nor to the THE rule.
Zeeman Transitions in Low Magnetic Field: Dependence of Line Shapes on the Asymmetry Parameter for Spin ≥ 3/2 Systems
Authors: Stephenson David , Smith John A. S.
Published: February 2015

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 vP ± vQ , where vQ corresponds to the Zeeman splitting of the ± 1/2 and/or the ± 3/2 levels in the small applied field, and vP 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.
Rapid Measurement of Nutation NQR Spectra in Powders Using an RF Pulse Train
Authors: Sinyavsky Nicolai , Ostafin Michał , Maćkowiak Mariusz
Published: February 2015

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 τ. It is shown that for an NQR frequency ω0 , frequency offset Δω, and pulse parameters satisfying the relation ω0τ + Δωtw = 2πk (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 3 5 Cl sites in polycrystalline 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride).
Measurement of Nuclear Quadrupole Interactions using Mössbauer Spectroscopy
Authors: Cook Desmond C.
Published: February 2015

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.
Molecular Origin of Glass Forming Tendency in Ternary Te-Se-Br(Cl) Chalcohalide Glasses
Authors: Bresser W. J. , Wells J. , Zhang M. , Boolchand P.
Published: February 2015

Bulk glasses of Te3 _zSez-(CI or Br)2+y , the composition spanning the glass forming range, were characterized by differential scanning calorimetry, 125Te absorption, and 129I emission Mössbauer spectroscopy. The results reveal that the stoichiometric glasses Te3(Cl or Br)2 consists of c-Te3 Cl2 -like chain fragments about 1.5 nm long and terminated by one-fold coordinated halogen atoms. The 125Te 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 (Tg
~ 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.
Mössbauer Effect in Biomedical Research: Variations of Quadrupole Splitting in Relation to the Qualitative Changes of Biomolecules
Authors: Oshtrakh M. I.
Published: February 2015

This review deals with studies of the variations of quadrupole splitting, electronic structure and stereochemistry of iron associated with qualitative changes of biomolecules. The possibility to determine various iron containing species resulting from the destruction of biomolecules using Mössbauer parameters is shown. A small change of iron stereochemistry leads to a small change of the iron electronic structure which could be detected by small changes of quadrupole splitting. It is expected that quadrupole splitting of iron gives new information for biomedical research on a molecular level.
Mössbauer Spectroscopy Evidence for Phase Selectivity in Excimer Laser Induced Amorphization of Thermally Annealed FeCoBSi Metallic Glass
Authors: Sorescu M. , Knobbe E.T.
Published: February 2015

Pulsed excimer laser irradiation effects (λ = 308 nm, τ = 10 ns, w = 3 J/cm2 , N = 2 laser pulses/spot, repetition rate 1 Hz) on the magnetic properties and phase composition of thermally annealed Fe66Co18B15Si1 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 crystallized Fe66Co18B15Si1 samples (T A = 648 K, t A = 1 hour) and was found to be accompanied by the development of laser-induced magnetic anisotropy. In totally crystallized Fe66Co18B15Si1 specimens (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 Fe66Co18B15Si1 specimens was shown to consist of partial amorphization and surface oxidation of the irradiated material.
Nuclear Quadrupole Interactions Studied by Time Differential Perturbed Angular Correlations of γ-Rays
Authors: Butz T.
Published: February 2015

This paper gives an elementary introduction to time differential perturbed angular correlation of γ-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 isotopes, and finally give some examples for modern applications.
Bayes’ Theorem Applied to the Selection of Models in PAC
Authors: Hemmingsen Lars , Hansen Steen
Published: February 2015

Using Bayes’ formula, the parameters in a given model fitting data from perturbed angular correlation of γ-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.
Hg-Coordination Studies of Cysteine Containing Oligopeptides
Authors: Tröger W. , Lippert C. , Schmidt P. , Schmidt U. , Butz T. , Hoffmann R. , Zeppezauer M. , Isolde
Published: February 2015

In order to study the interaction of cysteine containing peptide chains with Hg(II) the nuclear quadrupole interaction (NQI) of 199mHg in the Hg complex of the oligopeptide Alanine-Alanine-Cysteine-Alanine-Alanine (AACAA) was determined by time differential perturbed angular correla-tion. Different 199mHg-NQI’s for free and resin-bound AACAA were obtained. Furthermore, the 199mHg-NQI’s are influenced by the Hg:AACAA stoichiometry.
PAC Studies of Ag-Hf Intermetallic Compounds
Authors: Wodniecki P. , Wodniecka B. , Marszałek M. , Hrynkiewicz A. Z.
Published: February 2015

The hyperfine quadrupole interaction of 181Ta and 111Cd probes in HfAg and HfiAg com-pounds was studied at 24 to 1100 K with the time -differential perturbed angular correlation (TDPAC) technique. The EFGs measured in HfAg on 181Ta and 111Cd are 1.388(5)x1018 Vcm-2 and 0.340(5)x1018 Vcm -2 , respectively. For both probe atoms a linear decrease of the EFG with temperature was observed with slopes 1.11(2)x10-4 K-1 and 1.73(5)x10-4 K-1 for 181Ta and 111Cd, respectively. In Hf2 Ag, 0.469(2)x1018 Vcm-2 was determined on 181Ta nuclei and 0.428(5)x1018 Vcm-2 on 111Cd. Also a linear EFG temperature dependence with the large slope of 2.39(6)x10-4 K-1 was observed for 111Cd probes in Hf2Ag, while the EFG measured on 181Ta nuclei in this compound exhibits a very weak temperature variation which can be fitted neither with a linear T nor a T 3/2 dependence. In all cases the electronic contributions to the EFG are very small indicating that these transition element systems do not obey the universal correlation between the electronic and the ionic EFG observed in numerous other systems not belonging to the transition metal series.
17O Nuclear Quadrupole Coupling in Molecular and Lattice Systems by ab initio Calculation of Electric Field Gradients
Authors: Palmer Michael H.
Published: February 2015

We present ab initio Hartree-Fock calculations of electric field gradients, which are related to experimental determinations of nuclear quadrupole coupling constants. The nucleus of special interest is 17O but other nuclei in the molecules, especially 14N, 2H and 33S are included. The calculations were performed (a) as single molecules either at the SCF and MP2 correlated levels, (b) as clusters of molecules about a test site, or (c) as lattice calculations computed in the unit cell environment. The basis sets are triple zeta valence plus polarisation in (a). Because of limitations in exponent range in (c), the bases in both (b) and (c), where comparison was sought, are DZ at the SCF level.
Quadrupole Coupling in Purines and Pyrimidines by Hartree-Fock Lattice Calculations of Electric Field Gradients
Authors: Palmer Michael H.
Published: February 2015

We present ab initio Hartree-Fock lattice calculations on adenine, guanine and hypoxanthine, and some pyrimidines, including cytosine and uracil derivatives. The electric field gradients at the nitrogen centres are related to NQR experimental determinations of nuclear quadrupole coupling constants. The calculations were performed as lattice calculations in the unit cell environment, with 6-31G or double zeta basis sets at the SCF level. The present analysis strongly suggests that χzz at N3 in cytosine, N3 in guanine are both positive, and approximately tangential to the ring at that centre. In contrast, N7 in guanine is like most other azine-type N centres, with a largely radial direction for χzz. The 3-protonated cytosine ring has χzz as the local π-direction.
Ab-initio Band Structure Calculations and 61 Ni-Mössbauer Studies of BaNiO2 , BaNiO3 and CaNiN
Authors: Hannebauer B. , Schmidt P.C. , Kniep R. , Jansen N. , Walcher D. , Gütlich P. , Gottschall R. , Schöllhorn R. , Methfessel M.
Published: February 2015

The electron density distribution of the nickel compounds BaNiO2 , BaNiO3 and CaNiN has been investigated experimentally by 61Ni Mössbauer spectroscopy and theoretically by band structure calculations using the FP-LMTO (Full Potential Linear Muffin-Tin Orbital) method. For all compounds good agreement is found between the experimental and theoretical values of the electric field gradient qexp. and qtheor. at the nickel site.

BaNiO2 contains nickel in a square-planar coordination forming puckered chains of edge-sharing NiO4 squares. |q| at nickel is large: qexp = - 15.7(1.5) • 1021 Vm-2 and qtheor. = - 15.59 • 1021 Vm-2 .

The principal axis z is perpendicular to the NiO4 squares. The crystal structure of BaNiO3 contains face-sharing chains of NiO6 octahedra. In BaNiO3 q(Ni) is small: qexp. = ± 3.6(2.0) • 1021 Vm-2 and qtheor. = - 1.86 • 1021 Vm-2 . Because of the small broadening of the Mössbauer resonance line the sign of q could not be determined experimentally.

The nitridoniccolate CaNiN contains infinite linear chains 1
∞[NiN2/2 ] which run perpendicular to the c axis. Unexpectedly, |q(Ni)| in CaNiN is small: qexp. = 0.0 (2.0) • 1021 Vm-2 and qtheor. = - 3.05 • 1021 Vm-2. Again the sign of q(Ni) could not be determined experimentally. It is found theoretically that the small value of q(Ni) is caused by severe cancellation between σ and π contributions.
Conformational Analysis of Chloromethylenimine and its Hydrogen-Bonded Dimers with Water from the Study of Nuclear Quadrupole Interactions
Authors: Sathyan N. , Santhanam V. , Sobhanadri J.
Published: February 2015

A molecular conformation study on N-Chloromethylenimine and its 1:1 dimeric form with water has been carried out using the ab-initio method at 6-31 G and 6-31 G* basis set. We consider the two most stable conformers of the N-chloromethylenimine -water binary mixture involving double hydrogen bonds. In all cases the proton affinity has been calculated. Each system considered in this work has the nuclear quadrupole interactions of the nitrogen and chlorine resonant nuclei which have been calculated and compared. It is found that the nuclear quadrupole coupling constant for the nitrogen nucleus increases in the hydrogen bonded complexes and decreases for the chlorine nucleus compared to the monomeric values. The influence of proton affinity is reflected in the nuclear quadrupole coupling constant.
35Cl NQR of the N-Cl Bond and the Modified Townes-Daily Theory
Authors: Dolgushin G.V. , Lazarev I.M. , Nikitin P.A. , Larina L.I.
Published: February 2015

The modified Townes-Daily equation is shown to be better than the original one for frequencies of compounds having N-Cl bonds. Of the three semi-empirical methods AM 1, MNDO, PM 3, the first is preferable. The asymmetry parameters for the same compounds have been evaluated. The 35Cl NQR frequencies of two tautomers of N-chlorobenzotriazole are compared.
Nuclear Quadrupole Interactions as a Probe of Glass Molecular Structure
Authors: Boolchand P.
Published: February 2015

125Te absorption and 129I emission Mössbauer spectroscopies have proved to be the methods of choice to probe chalcogen chemical order in condensed matter using nuclear quadrupole interactions. In chalcogenide glasses, the technique has been unusually rewarding in decoding both the elements of local atomic structures and those of the medium-range atomic structures.
Magnetic Resonances of 51V, 209Bi, Mn2+, and Fe3+in BiVO4Single Crystals
Authors: Choh Sung Ho
Published: February 2015

Nuclear magnetic resonance (NMR) of 51V and 209Bi, and electron paramagnetic resonance (EPR) of Mn2+ and Fe3+ impurities in ferroelastic BiVO4 single crystals are reviewed. The nuclear quadrupole parameters and principal axes of the two host nuclei, 51V and 209Bi, and the second-or-der zero field splitting tensor of the isoelectronic 3 d5 ions, Mn2+ and Fe3+ , in BiVO4 are determined for the first time. Temperature dependence studies on 51V NMR and Mn2+ EPR confirmed that this crystal undergoes a second order phase transition. The substitutional sites of Mn2+ and Fe3+ in BiVO4 are Bi3+ and V5+, respectively.
Chlorine Substituted Acetic Acids and Salts. Effect of Salification on Chlorine-35 NQR
Authors: David Serge , Gourdji Michel , Guibé Lucien , Péneau Alain
Published: February 2015

The NQR of a quadrupolar probe nucleus is often used to investigate the effect of substituent in molecules. The inductive effect, based on a partial charge migration along the molecular skeleton is the only one present in saturated aliphatics, the conjugative effect appearing in conjugated molecules, especially aromatics. As the stepwise charge migration mechanism, formerly used to explain the inductive effect, is now believed obsolete, we have wanted to reexamined the case of chlorine substituted acetic acids and salts. The data in literature was extended by observing reso-nances and determining NQR frequencies in several acids and salts. The present analysis of the salification of mono-, di-and tri-chloroacetic acids, which is equivalent to a deprotonation or the substitution of the acid hydrogen by a negative unit charge, shows that a model based on the polarization of the chlorine atom(s) by the carboxyle group is consistent with experimental results: the polarization energy appears to be proportional to the NQR frequency shifts; experimental data show a correlation between the NQR frequency shifts accompanying salification and the variations of the intrinsic acidity measured in the gas phase; this, in turn shows that there is a proportionality between the polarization energy and the variations in the acid free enthalpy of dissociation. From the comparison between fluorine, chlorine, bromine and iodine, it also appears that an alternative mechanism, the polarization of the carboxyl group by the halogen, would be important only in the case of the fluoroacetic acid.
125I NQR Spectra of Iodobenzoic Acid and Iodophenol Derivatives. H-Bonds and C-I Characteristic Bonds of These Substances
Authors: Babushkina T. A. , Goltyapin Yu. V. , Gushchin S. I.
Published: February 2015

This is a review of investigations on iodo-benzoic acid, iodohippuric acid, and iodophenol derivatives by NQR, NMR, and emission Mössbauer spectroscopy. The influence of intermolecular, intramolecular, and bifurcated O-H…I and O-H…O bonds on the properties of iodine-carbon bonds is demonstrated. Ionized and non-ionized forms of tyrosine differ by the probability of H-bond formation. The simultaneous use of 127I NQR and emission Mössbauer 125I spectroscopy open the possibility to determine the types of tellurium-organic substances formed in the process of K-decay of 125I.
Powder Spectra of 51V NMR in CuV2S4: Possible Coexistence of Charge and Spin Density Waves
Authors: Nishihara H. , Todo N. , Hagino T. , Nagata S.
Published: February 2015

NMR experiments are reported for the copper chalcogenide spinel CuV2S4 , which has incommensurate lattice distortions at low temperatures in spite of the cubic symmetry at high temperature. A broad spin-echo spectrum of 51V has been observed below 90 K at 17 MHz. but it shows a remarkable frequency dependence where it becomes sharper with decreasing frequency. Possible coexistence of charge and spin density waves is suggested at low temperatures in this material.
Correlation between Structural, Infrared and Nuclear Quadrupole Resonance Data of Iodates
Authors: Petrosyan A.M. , Shishkin V.A.
Published: February 2015

The peculiarities of the structure and the IR and NQR spectra of acid iodates and pyroiodates which contain the I2O5 group are reported. Based in this, the results for several iodates that contain organic cations are considered.
121Sb NMR and SCF-MS-Xα Studies of Quadrupole Interaction and The Electronic Structure of Mixed-Valence Compound, Cs2SbCl6
Authors: Ueda Takahiro , Nakamura Nobuo
Published: February 2015

Cs2SbCl6 is known as a typical mixed-valence compound. It crystallizes into a tetragonal space group I41/amd and contains two different complex anions, Sb(III)Cl3-
6 and Sb(V)Cl-
6 . The dark blue color of this compound has been considered to originate from a charge transfer between the above two anions. In order to study the electronic structure of these complex anions and the existence of charge transfer between them we measured the 121Sb NMR spectrum and carried out molecular orbital calculations on the electronic states of these anions. The 121Sb NMR spectrum consists of two peaks at 0 and 30 kHz which can be assigned to the central transition of 121Sb in Sb(V)Cl-
6 and Sb(III)Cl3-
6 , respectively. The line shape analyses of the spectra led to nuclear quadrupole coupling constants of nearly zero for Sb(V)Cl-
6 and 4.9 ± 0.5 MHz for Sb(III)Cl3-
6 at room temperature. The quadrupole coupling constant of 121Sb(III) decreases steadily on heating. The calculations of the electronic ground state energies of both anions were calculated by the MS-Xα molecular orbital method. The calculated charge-transfer band from the A1g state of Sb(III)Cl3-
6 to the A1g state of Sb(V)Cl-
6 appears at 610 nm and can account for the experimental electronic spectrum, the calculated quadrupole coupling constant in Sb(III)Cl3-
6 however is far larger than the experimental one. The contribution of the charge-transferred state to the ground state is negligible and so the temperature dependence of the quadrupole coupling constant of 121Sb(III) is attributed to an anisotropic thermal expansion of the compound.
Nuclear Spin-Lattice Relaxation of a Spin System with Strong Heteronuclear Magnetic Interaction
Authors: Furman G. B. , Kunoff E. M. , Goren S. D.
Published: February 2015

Results are presented of a theroretical consideration of the nuclear quadrupole resonance and spin-lattice relaxation for a sample containing nuclei of two different types coupled by strong heteronuclear dipole-dipole interactions and influenced by an external continuous or pulsed ra-diofrequency magnetic field acting only on the nuclei of one sort with spin I > 1/2. A kinetic equation is obtained from which the time dependence of the magnetization of the sample is derived. The kinetic coefficients are calculated as a function of the concentration and distribution of the nuclei of both sorts.
35Cl NQR Study of Thermoactivated Motions of Nitro Groups in Picryl Chloride
Authors: Kyuntsel Igor A.
Published: February 2015

The temperature dependences of the 35Cl NQR frequency (ν), spin-lattice relaxation time (T1), and spin-spin relaxation time (T2) have been studied in 2,4,6-trinitrochlorobenzene (picryl chloride) from 77 K up to the melting point (354 K). The T1(T) curve exhibits a pronounced composite mimimum near 300 K which gives evidence for the reorientations of the two ortho-NO2 groups around their two-fold symmetry axes with the activation energies of 27.4 kJ mol - 1 and 31.2 kJ mol - 1. These values can be related to the ortho-NO2 groups having the twist angles of 33° and 81°, respectively (the crystal structure of picryl chloride is known). The T2(T) dependence exhibits interesting features, too: a deep minimum about 140 K and a new rapid decrease above 270 K.
Spin Reorientation Phenomena in (R1 - xR´x)2Co14B Compounds
Authors: Myojin T. , Ohno T. , Mizuno K. , Tsujimura A. , Kojima K.
Published: February 2015

The variation of NMR spectra and magnetization with temperature in (R1 - xR´x)2Co14B (R = Y or Gd, R´ = Tb. Dy or Ho 0 ≤ x ≤ 1) have been measured. These compounds undergo spin reorientation at a temperature TSR when Y and Gd are substituted by Tb, Dy and Ho, and the temperature TSR increases with the fraction x. Phase diagrams of spin arrangement in these systems have been obtained. The results are discussed from the view point of competition between the crystalline electric field and the Co-R exchange interaction.
A Pulsed 35Cl NQR Study on the Molecular Motions and Phase Transition of 4-Chlorobenzyl Alcohol
Authors: Niki Haruo , Kano Kikuhiro , Hashimoto Masao
Published: February 2015

The spin-lattice and spin-spin relaxation times T1 and T2 of 35Cl NQR were measured for the high (I) and low (II) temperature phases of 4-chlorobenzyl alcohol in the range 50 < T/K < 338 (transition and melting points: 236 and 343.5 K, respectively). In phase II the T1 behavior in the range 50 < T/K < 90 can be explained by lattice vibrations and that in the range 90 < T/K< 190by reorientation with an activation energy of ca. 3.8 kJ/mol. In phase I, the T1 behavior at T > 260 K is explainable by another reorientation with Ea ≈ 4.7 kJ/mol. The T1, vs. T curves revealed that in both phases the crystal dynamics is anomalous in the vicinity of the transition temperature. Lattice defects accumulated in phases I and II by the phase transition were found to be responsible for the extremely short inverse line width parameters (T2*).
NQR Investigation of Anion Dynamics in Rb2Zn(Cl1 - xBrx)4
Authors: Subramanian R. K. , Maheswari S. Uma , Venu K. , Sastry V. S. S.
Published: February 2015

The structural stability of Rb2Zn(Cl1 - xBrx)4 (x = 1% and 3%) is investigated using the 35Cl quadrupole resonance frequency and spin lattice relaxation time (T1Q) in the paraelectric (PE) phase. The PE to incommensurate (IC) phase transition temperature T1, observed at 302 K in the pure compound, is lowered to 300 K for x = 1 % and to 293 K for x = 3%. These effects are smaller than in the earlier reported case of 3% Cs substitution in Rb2ZnCl4 , which reduces T1 by 25 K. While bigger cation substitution affects only the barrier for anion dynamics about directions perpendicular to the a-axis (direction of low temperature IC modulation wave), bigger anion substitution is found to affect the barrier for anion dynamics about the a-axis as well. The present study also indicates that the cusp like dip in T1Q observed while approaching T1 from above (characterizing the soft mode condensation associated with the structural phase transition) is essentially unaffected by anion impurity substitution, in contrast to the case where bigger cation substitution tends to smear the transitional effects. These results seem to suggest the dominant role played by cations in stabilizing the PE phase of these A2BX4 systems, in comparison to anions.
35Cl NQR in Solid Trichloroacetyl Halides
Authors: Gordeev A. D. , Osipenko A. N. , Soifer G. B.
Published: February 2015

By 35Cl NQR the temperature dependences of the resonance frequencies and spin-lattice relaxation times for the 35Cl nuclei have been studied in solid CCl3COHal (Hal = F, CI, Br, I). A linear correlation between the average 35Cl NQR frequencies of the CCl3 groups and the electronegativities of the halogen atoms in the COHal groups has been discovered. The temperature-dependent NQR data reveal thermoactivated reorientations of the CCl3COHal molecules as a whole in the crystal lattice. The activation energies of this motion are found to lie in the range 31 - 37 kJ mol - 1
Inter-plane Coupling and Spin Gap -an NMR/NQR Look on Typical Properties of High-Temperature Superconductors
Authors: Brinkmann D.
Published: February 2015

The paper discusses some NQR/NMR studies performed on Y-Ba-Cu-O superconductors at the University of Zürich. In particular, we review studies performed in Y2Ba4Cu7O15 by measuring various planar Cu NQR/NMR parameters: the spin-lattice relaxation time, the Knight shift and the indirect component of the Gaussian contribution to the spin-spin relaxation time. The temperature dependence of these parameters reveals a coupling between adjacent planes of a double plane. The existence of the inter-plane coupling has independently been confirmed by performing NQR Spin-Echo Double Resonance (SEDOR) experiments. The appearance of a spin gap seems to be the consequence of inter-plane coupling.
Ru NMR and NQR Studies in CeRu2
Authors: Ishida K. , Mukuda H. , Kitaoka Y. , Asayama K. , Onuki Y.
Published: February 2015

We have carried out Ru NMR and NQR measurements in superconductor CeRu2 having Tc = 6.1 K in the temperature range of 1.3-30 K. From the 99Ru NMR in 10.2 T above Hc2 , T1T = const was found in the measured-T range, and the value of T1TK2 is almost the same as that in the uncorrelated Korringa relation, suggesting that there does not exist the strong spin fluctuation of Ru d-spins. The property of the superconducting state was investigated by using Ru NQR. We observed the Hebel-Slichter peak just below T c and the exponential decrease in 1/T1 indicating that this superconductivity has an ordinary s-wave character. The effect of Al substitution for Ru was also studied by NMR and NQR.
Cu(1) NQR in Y1 _ xPrxBa2Cu3O7
Authors: Ohno Takashi , Nishihara Hironori , Koyama Kuniyuki , Yasuoka Hiroshi
Published: February 2015

Cu(1) NQR spectra of the CuO chain site in Y1 _ xPrxBa2Cu3O7 (x = 0.1 and 0.2), and the 63Cu(1) NQR spin-lattice relaxation rates 1/T1 in Y0.9Pr0.1Ba2Cu3O7 have been measured. The half widths are about three times wider than those of the pure YBa2Cu3O7 . The peak frequencies are lowered by the Pr doping. This seems to indicate a decrease of on-site holes at the Cu(1) site. The relaxation rate 1/T1 is found to obey the same temperature dependence, 1/T1 = aT + bT3 as reported for pure YBa2Cu3O7.
On the Shock Front Thickness in Water and other Molecular Liquids
Authors: Hess Siegfried
Published: February 2015

Theoretical explanations are presented for the deviation of the shock front thickness from linear hydrodynamics, as observed by W. Eisenmenger (1964) in water and several molecular liquids for large driving pressure differences. Two mechanisms are proposed, which are based on generalizations of the Maxwell relaxation equation for the friction pressure tensor. One is due to the spatial inhomogeneity and linked with piezo-electric or piezo-tetradic effects. The other is caused by nonlinearities which account for shear thickening.
Structure of Ni-P Melts by X-Ray Diffraction
Authors: Sedelmeyer B. , Steeb S.
Published: February 2015

X-ray diffraction was done with molten Ni81 P19 (930°C) and with molten Ni68.8 P31.2 (1160°C). The second peak of the structure factor and the pair correlation function of the Ni81P19 -melt shows a shoulder, as was observed for amorphous Ni80P20 . The first two peaks in the pair correlation function can be modelled using crystalline Ni3 P besides molten Ni. In the case of Ni68.8P31.2 , the first peak in the pair correlation function was modelled using the distance and coordination number as in crystalline Ni2P.
Temperature Effect on the Absorption and Fluorescence Spectra of p-Cyano-N,N-dimethylaniline in Dichloroethane and Ethyl Acetate
Authors: Kawski A. , Piszczek G.
Published: February 2015

The effect of temperature (293 ÷ 413 K) upon absorption and fluorescence spectra of p-cyano-N,N-dimethylaniline (CDMA) was investigated in 1,2-dichloroethane and ethyl acetate. Two fluorescence bands, a and b, were already observed at 293 K, with the intensity of band b increasing strongly with temperature in both solvents. The absorption and fluorescence b bands of CDMA were found to be independent of the orientation interaction with the solvent. On the other hand, the longwave band of fluorescence a undergoes a strong hypsochromic shift resulting from the decrease in the permittivity with increasing temperature. Based on these observations, the electric dipole moment μe in the 1Lb state (shortwave band of fluorescence b) was found to be equal to the dipole moment,μg, in the ground state. The electric dipole moment μe in the 1La state (the longwave band of fluorescence a), which is strongly stabilized by the polar solvent, is about 2.5 times as high as μg , amounting to 54 x 10- 0 Cm (16.2 D) for μg = 22.5 x 10 -30 Cm (= 6.75 D).
Notiz: The Microwave Spectrum of the Benzonitrile-Water Complex
Authors: Storm V. , Consalvo D. , Dreizler H.
Published: February 2015

We report on the measurement and assignment of the benzonitrile-water complex rotational spectrum in the vi-bronic ground state. This study was facilitated by a newly constructed low frequency molecular beam Fourier trans-form microwave spectrometer.
Notiz: A Symbolic Computation-Based Method and Two Nonlinear Evolution Equations for Water Waves
Authors: Gao Yi-Tian , Tian Bo
Published: February 2015

A symbolic-computation-based method, which has been newly proposed, is considered for a (2+1)-dimensional generalization of shallow water wave equations and a coupled set of the (2 +1)-dimensional integrable dispersive long wave equations. New sets of soliton-like solutions are constructed, along with solitary waves.
ab initio Calculation of 33S Quadrupole Coupling Constants. Reanalysis of the 33S Hyperfine Structure in the Rotational Spectrum of Thiirane
Authors: Kirchner Barbara , Huber Hanspeter , Steinebrunner Gerold , Dreizler Helmut , Grabow Jens-Uwe , Merke Ilona
Published: February 2015

We present quantum chemical calculations on the MP4(SDQ) level with basis sets of high local quality to determine the nuclear quadrupole coupling tensor of 33S in a series of molecules, which were investigated up to now by microwave spectroscopy. The analysis of the nuclear quadrupole coupling in the rotational spectra provided experimental information on the tensors. As an example for such an analysis, improved values for thiirane, C2H4
33S, are given: χaa = - 32.9425(78) MHz, χbb = -16.402(14) MHz, χcc = 49.345(14) MHz.
Anisotropie Interaction Potentials for He-Pyrrole, He-Furane and He-Thiophene from total Differential Cross Section Measurements
Authors: Schmidt Ralf , Gebauer Christian , Klein Olaf , Seidel Wolfhart
Published: February 2015

Differential cross section measurements are reported for scattering of an improved He-atomic beam by crossed beams of Pyrrole, Furane and Thiophene. The damping of the DCS diffraction oscillations is used to extract reliable anisotropic intermolecular potentials, applying the infinite order sudden approximation (IOSA).
EPR of Gd3+ in Sulfate Host Crystals of Low Symmetry
Authors: Bode M. , Mosel B. D. , Müller-Warmuth W.
Published: February 2015

Electron paramagnetic resonance (EPR) spectra of trivalent gadolinium have been investigated in orthorhombic sulfate host crystals MeSO4 with Me = Sr, Ba, Cd, Hg, Pb and K2SO4 . Because of the low symmetry of the host crystals and the spin quantum number 7/2, complex spectra for several orientations of the magnetic field containing a large number of individual lines had to be analyzed. The spin Hamiltonian parameters have been rigorously determined from the rotational diagrams. Gd3+ has been found to substitute, first of all, for the monoclinic sites of the host metal ion with charge compensation at larger distances. To a small extent, charge compensation in the vicinity has also been observed, arising from additional centres and spectra with lower intensities. Correlations between EPR spectra and crystal structure are reflected in the values of the zero field splitting parameters.
On the Variant Boussinesq Equations
Authors: Gao Yi-Tian , Tian Bo
Published: February 2015

We extend the generalized tan h method to the variant Boussinesq equations and obtain certain solitary-wave and new exact solutions.
A New Nuclear-Quadrupole Double-Resonance Technique based on Solid Effect
Authors: Seliger J. , Žagar V.
Published: February 2015

A new nuclear-quadrupole double-resonance technique is described. It has a higher sensitivity and a higher resolution than the conventional nuclear-quadrupole double-resonance technique based on solid effect. The new technique involves magnetic field cycling between a high and a low static magnetic field and simultaneous application of two rf magnetic fields when the sample is in the low static magnetic field. A strong rf magnetic field induces "forbidden" simultaneous transitions in a magnetic (usually 1H) and in a quadrupole spin system and thus couples the two spin systems. A weak rf magnetic field induces transitions between the energy levels of the quadrupole nuclei and simulates a fast spin-lattice relaxation of the quadrupole nuclei when its frequency matches an NQR frequency. The sensitivity and resolution of the new technique are discussed and test measurements in tris-sarcosine calcium chloride are presented.
Thermodynamics of ß-cyclodextrine/water Interactions
Authors: Margheritis C. , Marini A. , Sinistri C.
Published: February 2015

From a purely enthalpic standpoint, the ß-CD hydration, as studied by semiempirical calculations, appears improbable, in contrast to experiment. For the spontaneous hydration process, a compensation mechanism, connected with substrate stabilization and/or entropy increase, is suggested on the basis of simple thermodynamic considerations. The analysis is done on the basis of a single parameter Ew (> 0), which represents the energy needed to transfer a mole of water from the liquid to the ß-CD absorbed phase.

The model, although simple, allows predictions largely consistent with the experimental results, while suggesting possible interpretations.
Thermochemical Nonequilibrium in Rapidly Expanding Flows of High-Temperature Air
Authors: Nishida Michio , Matsumotob Masashi
Published: February 2015

• This paper describes a computational study of the thermal and chemical nonequilibrium occuring in a rapidly expanding flow of high-temperature air transported as a free jet from an orifice into low-density stationary air. Translational, rotational, vibrational and electron temperatures are treated separately, and in particular the vibrational temperatures are individually treated; a multi-vibrational temperature model is adopted. The governing equations are axisymmetric Navier-Stokes equations coupled with species vibrational energy, electron energy and species mass conservation equations. These equations are numerically solved, using the second order upwind TVD scheme of the Harten-Yee type. The calculations were carried out for two different orifice temperatures and also two different orifice diameters to investigate the effects of such parameters on the structure of a nonequilibrium free jet.
Notiz: Modification of the Generalized tanh Method with sech Function for Generalized Hamiltonian Equations
Authors: Tian Bo , Zhao KeYi , Gao Yi-Tian
Published: February 2015

We modify the generalized tanh method with the sech function, so as to obtain a new class of the soliton-like solutions to a coupled set of generalized Hamiltonian equations.
Das Teilchen im Kasten: Strukturen in der Wahrscheinlichkeitsdichte / The Particle in a Box : Structures in the Probability
Authors: Stifter P. , Leichtie C. , Schleich W. P. , Marklof J.
Published: February 2015

Recently W. Kinzel found characteristic structures, e. g. canals and ridges, in the contour plot of the quantum probability density of a particle moving in a box with infinitely high walls. Using the Wigner function we provide an analytical explanation of this numerical observation. Moreover we demonstrate that similar space-time structures also appear in other potentials, such as the one governing the vibrational motion of a diatomic molecule.
Fingerprints of Superpositions of Multifractals and Second Order Phase Transitions
Authors: Stoop Ruedi
Published: February 2015

The generic model of superimposed multifractal measures is discussed from the generalized entropy point of view. Natural conditions for the existence of second order critical lines are given. The second order phase transitions may manifest themselves in stopping points of the entropy-like thermodynamic functions. The findings are of experimental relevance.
Is the Uncertainty Relation at the Root of all Mutual Exclusiveness?
Authors: Sen D. , Basu A. N. , Sengupta S.
Published: February 2015

It is argued that two distinct types of complementarity are implied in Bohr's complementarity principle. While in the case of complementary variables it is the quantum mechanical uncertainty relation which is at work, the collapse hypothesis ensures this exclusiveness in the so-called wave-particle complementarity experiments. In particular it is shown that the conventional analysis of the double slit experiment which invokes the uncertainty principle to explain the absence of the simultaneous knowledge of the which-slit information and the interference pattern is incorrect and implies consequences that are quantum mechanically inconsistent.
Absorption, Fluorescence and Emission Anisotropy Spectra of 4-Cyano-N,N-dimethylaniline in Different Media and at Different Temperatures
Authors: Kawski A. , Piszczek G.
Published: February 2015

The effect of temperature on fluorescence and emission anisotropy spectra of 4-cyano-N,N-dimethylaniline (CDMA) was investigated in viscous (glycerol and paraffin oil) and rigid (polyvinyl alcohol) PVA and polyvinyl chloride) PVC) media. A strong effect of temperature on the intensity of a and b emission bands was observed. It was also found that the emission anisotropy, r, does not vary in the longwave emission band a at a fixed temperature but decreases in the emission band b together with the decreasing wavelength. The latter effect is due to the fact that the transition moment in this band is perpendicular to the long axis of the CDMA molecule. For CDMA in paraffin oil, a normal b band with negative emission anisotropy only occurs. In all other media used, the emission anisotropy has lower values, approaching zero, which results from the considerable covering of band b with a broad emission band a.
Structure of Fe-Si-melts by X-ray Diffraction
Authors: Sedelmeyer B. , Steeb S.
Published: February 2015

X-ray diffraction was done with molten Fe66,7 Si33,3 and molten Fe33,3 Si66,7 . The coordination numbers versus the concentration lie above the connection line between the coordination numbers of the unalloyed molten elements Fe and Si, respectively, which means a tendency for microsegregation. The pair correlation function of molten Fe66,7 Si33,3 was modeled using the data of crystalline Fe2 Si. At the same time, the pair correlation function of the molten alloy Fe33,3 Si66,7 can be modeled using the data of the corresponding crystalline alloy. Thus for molten Fe33,3 Si66,7 microsegregation into FeSi2 and Si or FeSi and for molten Fe66,7 Si33,3 microsegregation into Fe2 Si and Fe or FeSi exists.
Helium Atom Scattering from Cyclopentane, Pyrrolidine and Tetrahydrofurane in Crossed Molecular Beams
Authors: Gebauer Christian , Klein Olaf , Schmidt Ralf , Seidel Wolfhart
Published: February 2015

Scattering of helium atoms by cyclopentane, pyrrolidine and tetrahydrofurane molecules was ob-served in crossed molecular beam experiments. The intensity of scattered helium atoms, depending on the scattering angle, was measured with high resolution, and the damping of the diffraction oscillations of the differential cross sections was used to extract elastic anisotropic interaction potentials for these molecules. The evaluation included a geometric transformation concerning the puckered states of the envelope and the twisted conformation of the molecules. The potentials were found to be rather similar.
Photoconductivity of an Anthracene / 2,2,4,4-Tetramethylpentane Solution: Pressure Effect on the Photoionization of Solute and Solvent
Authors: Katoh Ryuzi , Lacmann Klaus , Schmidt F.
Published: February 2015

The photoconductivity spectrum of a solution of anthracene (AN) in 2,2,4,4-tetramethylpentane (TMP) was measured as a function of pressure up to 2 kbar. The threshold energies of photoionization of the solute (AN) and of the solvent (TMP) increase with pressure. The relative quantum yield for charge carrier generation decreased with increasing pressure. The concomitant reduction of the initial separation distance of the geminate charge carrier pairs may be due to an increase of the number of inelastic collisions caused by the increased density of the liquid within the sphere of Coulomb attraction of the positive ion.
Internal Mobilities in the Molten Binary Systems (Tl, K)NO3 and (Tl, Cs)NO3
Authors: Chou P.-H. , Okada I.
Published: February 2015

Ratios of internal cation mobilities in the molten binary systems (Tl, K)NO a and (Tl, Cs)NO3 have been measured by the Klemm method. From these and the data available on the densities and electric conductivities, the internal mobilities b have been calculated. While generally in the mixtures of TlNO3 with alkali nitrates at constant temperature the conductivities and internal mobilities decrease with increasing molar volume, in (Tl, K)NO3 they decrease with decreasing molar volume. This is explained by the high polarizability of the Tl + ions.
Quantum Mechanics as a Generalization of Nambu Dynamics to the Weyl-Wigner Formalism
Authors: Bialynicki-Birula Iwo , Morrison P.J.
Published: February 2015

It is shown that Nambu dynamics can be generalized to any number of dimensions by replacing the 0(3) algebra, a prominent feature of Nambu's formulation, by an arbitrary Lie algebra. For the infinite dimensional algebra of rotations in phase space one obtains quantum mechanics in the Weyl-Wigner representation from the generalized Nambu dynamics. Also, this formulation can be cast into a canonical Hamiltonian form by a natural choice of canonically conjugate variables.
Time Reversal Symmetry and Humpty-Dumpty
Authors: Englert Berthold-Georg
Published: February 2015

It is argued that the quantal evolution of a physical system is fundamentally irreversible although the dynamical equations are symmetric under time reversal. The example of spin coherence in a Stern-Gerlach interferometer demonstrates that even undoing the evolution partially only may require sub-microscopic precision in controlling a macroscopic apparatus.
Is There a Preferred Canonical Quantum Gauge?
Authors: Aharonov Y. , Anandan J.
Published: February 2015

The interaction between a long solenoid and a quantized charged particle in the field free region outside it is studied treating both systems quantum mechanically. This leads to a paradox which suggests that when the electromagnetic field is quantized, there may be a preferred quantum gauge for the vector potential. This paradox is resolved by canonically quantizing the system in a different gauge in which the classical Lagrangian contains an acceleration dependent term.