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1978[X]
161Author    Taiju Tsuboi, JaK. YotoRequires cookie*
 Title    Optical and Thermal Electron Transfer in KCl: T l+ Crystals  
 Abstract    The absorption spectra of Tl2+ in KCl crystals have been measured from 77 to 300 K. T l2+ gives rise to five absorption bands peaking a t 1760, 860, 680, 460 and 233 nm. These oscillator strengths have been calculated. Optical excitation in the 460 nm band destroys th e Tl2+ and T l++ bands and produces the Tl° bands. Thermal excitation of a crystal containing only Tl2+ and T1++ results in the simultaneous decay of Tl2+ and T l++. I t is concluded th a t electrons released from Tl2+ by optical or therm al excitation are trapped a t T1+ and T1++. A discussion is given on Tl2+++: A Tl2+++ which has an absorption band a t 1075 nm is formed when a (Tl+)2 traps a positive hole of a nearby Cl2~, whereas it is deformed when a T l2+++ trap s an electron released from a Tl2+ by optical excitation in th e 460 nm band. 
  Reference    Z. Naturforsch. 33a, 1154—1157 (1978); received Jan u a ry 2 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1154.pdf 
 Identifier    ZNA-1978-33a-1154 
 Volume    33 
162Author    K. Gärtner, M. W. EstphalRequires cookie*
 Title    Einfluß des Präparationsverfahrens auf das Restwiderstandsverhältnis kleiner Niobkugeln  
 Abstract    In s titu t für W erkstoffe der Elektrotechnik an der R uhr-U niversität Bochum A technique for preparing spherical niobium samples of high purity is described. The prepara­ tion of tunneling junctions sta rts from such spheres. The influence of tem perature gradients during a h e a t treatm en t on the sample p u rity is discussed. 
  Reference    Z. Naturforsch. 33a, 1158—1160 (1978); eingegangen am 18. Ju li 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1158.pdf 
 Identifier    ZNA-1978-33a-1158 
 Volume    33 
163Author    H. E. Wilhelm, S. H. Hong, D. A. BoonzaierRequires cookie*
 Title    Boundary-Value Problem for Electromagnetic Fields in Cylindrical Conductor with Circumferential Electrodes Excited by AC-Current  
 Abstract    The bounardy-value problem for the electrom agnetic fields E(r, t) = {Er(r, z, t),0, Ez(r, z, t)} and B(r, t) = {0, Bg(r, z, <),0} in an electrically conducting cylinder of radius r = a and infinite length (— oo ^ 2 ^ -f-oo) is treated , which are excited by a periodic ac-current I(t) = I0cosojt entering and leaving the cylinder through circumferential electrodes a t r = a and z = ± c. Solu­ tions for E(r, t) and B(r, t) are obtained in term s of Fourier integrals which are reduced to in­ finite series by means of the residue theorem. Graphical presentations of th e fields E(r, z, t) and B(r, z, t) versus 2 and r for tim es lot = 0 and nj2 are given which show th e relative am plitude and phase relations of the fields. An application of the results to medical physics is discussed con­ cerning the measurement of the electrical conductivity of th e tissue of limbs. 
  Reference    Z. Naturforsch. 33a, 1161 (1978); received Ju n e 12 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1161.pdf 
 Identifier    ZNA-1978-33a-1161 
 Volume    33 
164Author    G. Winnewisser, R. A. Creswell, M. WinnewisserRequires cookie*
 Title    Formation of Cyanopolyynes in Gas Discharges  
  Reference    Z. Naturforsch. 33a, 1169—1172 (1978); received Ju ly 26 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1169.pdf 
 Identifier    ZNA-1978-33a-1169 
 Volume    33 
165Author    F. F. Ratev, P. E. Polansky, NikolovRequires cookie*
 Title    Calculation of C N D O Characters Orders with Account of Virtual Pars Orbital Contributions  
 Abstract    The contribution of virtual pars orbitals to the occupied molecular orbitals is taken into account in the CNDO approximation. On this basis a new index ~ ql is introduced, which is similar to the character order ql in the ^-electron approximation. The calculated values of ql for the 19 com­ pounds under investigation correlate well with the experimental bond lengths, as well as with a number of other physical and chemical properties. 
  Reference    Z. Naturforsch. 33a, 1173—1178 (1978); received on Ju ly 14 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1173.pdf 
 Identifier    ZNA-1978-33a-1173 
 Volume    33 
166Author    Klaus Wegmann, OttoE. RösslerRequires cookie*
 Title    Different Kinds of Chaotic Oscillations in the Belousov-Zhabotinskii Reaction  
 Abstract    In s titu t für Physikalische und Theoretische Chemie der U niversität Tübingen and In stitu t für Theoretische Physik der U niversität S tu ttg a rt Following earlier evidence for chaotic tim e behaviour in th e open flow continuous stirred Belousov-Zhabotinskii reaction based on a single m easured observable, now two-dimensional phase plots are presented. The potential of a brom ide ion sensitive electrode was plotted against the electrochemical potential. In th e two-dimensional observation space obtained, both apparent limit cycle oscillations and ap p aren t chaotic oscillations were observed. Of the latter, type 1 resem­ bles a double-limit cycle system w ith fluctuation-triggered transitions between the two regimes (exogenous chaos); type 2 is analogous, b u t here th e irregular transition between the two oscilla­ tory regimes gives the impression of being, in principle, independent of exogenous noise. I f so, this flow may be related to one of the chaotic flows w ith saddle point known (for example, the Lorenz attractor). Type 3, only observed as a tran sien t so far, looks like a two-dimensional projec­ tion of screw type chaos, which is one of the simplest types of determ inistic chaos. Type 4 corres­ ponds either to a fluctuation-triggered monoflop (exogenous chaos) or to folded-strip (spiral) tvpe chaos. 
  Reference    Z. Naturforsch. 33a, 1179—1183 (1978); received Ju ly 19 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1179.pdf 
 Identifier    ZNA-1978-33a-1179 
 Volume    33 
167Author    J. Zuluaga, P. MartinezRequires cookie*
 Title    Kinetics of the Reversible Transformation of 2,3-Dioxogulonic Acid into its Enol as a Function of the pH of the Medium  
 Abstract    2,3-dioxogulonic acid and the disodium salt of its enol were synthesised, isolated and identified both chemically and spectroscopically. A kinetic study was carried out on its equilibrium by means of the "stopped flow" method for rapid processes, and the rate constants for the forward and backward reaction were determined as a function of the pH of the medium. The kinetic coefficients involved, equilibrium constant and Gibbs free energies were also determined. 
  Reference    Z. Naturforsch. 33a, 1184—1189 (1978); received June 27 1977 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1184.pdf 
 Identifier    ZNA-1978-33a-1184 
 Volume    33 
168Author    K. F. Dössel, D. H. SutterRequires cookie*
 Title    Microwave Spectrum of (SiH3)2X, X = 0,S, ^-Structure, Molecular Electric Dipolemoment and Barrier to Internal Rotation of Disilylsulfide  
 Abstract    The rotational spectrum of SiH3-S-SiH 3 in its vib-torsional ground state has been investigated in the frequency range between 8 and 40 GHz. From the absolute frequencies and torsional splittings a rigid-top-rigid-frame ro-structure could be derived. The molecular electric dipole moment was determined from the second order Stark effect of some AA-species rotational transitions. The analysis of the microwave spectrum of the related molecule SiH3-0 -SiH 3 was yet unsuccessful. However several features of the observed spectrum rend support to the idea of a "quasi-linear" double rotor molecule with a relatively low energy hump for the linear con­ figuration of the Si-O-Si-chain. 
  Reference    Z. Naturforsch. 33a, 1190—1196 (1978); received July 28 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1190.pdf 
 Identifier    ZNA-1978-33a-1190 
 Volume    33 
169Author    W. Hagele, D. Schmid, F. Drissler, J. Nauš, H.C W OlfRequires cookie*
 Title    Optical Spectra of Chlorophyll a and b Molecules and Complexes in PMMA and MTHF  
 Abstract    The optical spectra of chlorophyll a and chlorophyll b in PMMA and MTHF were studied over a wide range of concentration (8 X 10-6—1 X 10-3 mole/1 in PMMA, and 10_6—10_1 mole/1 in MTHF). In the absorption spectra it is possible to identify bands which originate from chlorophyll disolvates and chlorophyll monosolvates in MTHF as well as bands which are most probably due to isolated chlorophyll molecules in PMMA. In high-concentration samples of chlorophyll in MTHF some bands may be assigned to aggregates, but based on optical results only, no particular model can be proposed. The emission spectra are strongly influenced by reabsorption and energy transfer processes. However, the so-called Qy band of isolated molecules in PMMA and of chloro­ phyll monosolvates in MTHF as well as the Qx and the Qy bands of chlorophyll disolvates in MTHF can be identified unequivocally in the fluorescence spectra. 
  Reference    Z. Naturforsch. 33a, 1197—1205 (1978); received July 19 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1197.pdf 
 Identifier    ZNA-1978-33a-1197 
 Volume    33 
170Author    Michael ConradRequires cookie*
 Title    Heuristic Considerations Suggesting a Role for Electron Pairing in Thermodynamically Consistent Pathways of Enzyme Catalysis  
 Abstract    Nuclear motions accompanying enzyme catalysis are described in terms of a hypothetical reaction mechanism in which instabilities of electronic structure arise from short-lived pairing resonances of parallel spin electrons. A pairing interaction is proposed which has its basis in confinement constraints imposed by complex formation. 
  Reference    Z. Naturforsch. 33a, 1206—1209 (1978); received July 26 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1206.pdf 
 Identifier    ZNA-1978-33a-1206 
 Volume    33 
171Author    Levente SzaszRequires cookie*
 Title    Hartree-Fock Approximation with Pseudowavefunctions  
 Abstract    By the introduction of pseudopotentials the Hartee-Fock equations for all electrons of an atom or molecule are exactly transformed into equations yielding orbitals which are non-ortho-gonal to the lower lying states. 
  Reference    Z. Naturforsch. 33a, 1210—1211 (1978); received June 16 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1210.pdf 
 Identifier    ZNA-1978-33a-1210 
 Volume    33 
172Author    Kin-Ichi MasudaRequires cookie*
 Title    Electronic Theory for Cleaved Alloys: Effects of Off-Diagonal Disorder  
 Abstract    The tight-binding type theory for cleaved alloys by Bennemann et al. has been extended to include the effects of the random transfer integrals (off-diagonal disorder). The chemisorption and segregation behavior of cleaved alloys is investigated in detail including both the diagonal and off-diagonal disorder. I t is demonstrated th at the effects of the off-diagonal disorder are very important for the electronic properties of cleaved alloys. The theory has further been used to study the electronic structure of metal surfaces with substitutional disorder as well as to inves­ tigate the changes in the density of states due to the order-disorder phase transition in chemi-sorbed layers. 
  Reference    Z. Naturforsch. 33a, 1212—1223 (1978); received July 18 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1212.pdf 
 Identifier    ZNA-1978-33a-1212 
 Volume    33 
173Author    Jon Brunvoll, Istvan Hargittai, Maria KolonitsRequires cookie*
 Title    Electron Diffraction Investigation of the Molecular Structure of Trifluoromethyl Sulphonyl Chloride  
 Abstract    An electron diffraction investigation yielded the fol­ lowing geometric parameters for trifluoromethyl sulphonyl chloride rg(C -F) 1.326(4), rg(S=0) 1.416(7), r"(S -C l) 2.016(5), rg(S—C) 1.857(6) Ä, < £ 0 = S -C 108.3(7)°, <£C—S—Cl 98.7(4)°, <£0 = s =0 122.4(10),° <£0 = S -C 1 108.3(3)°, <£ F —C—F 109.9(3)°. The S -C bond is in CF3SO2CI by almost 0.1 A longer than in CH3SO2CI. 
  Reference    Z. Naturforsch. 33a, 1236—1238 (1978); received May 30 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1236_n.pdf 
 Identifier    ZNA-1978-33a-1236_n 
 Volume    33 
174Author    S. Chaudhari, T. R. Joshi, R. V. JoshiRequires cookie*
 Title    Phosphorescence Decay in Thallium-Doped Ammonium Chloride  
 Abstract    The phosphorescence decay rates of thallium-doped ammonium chloride (NHUChTl) phosphors, prepared by crystallization from aqueous solution, have been studied at room temperature for near-ultraviolet emission. The effects of impurity concentration as well as thermal and/or mechanical treatm ent on the decay rates have been examined. Phosphorescence centres consisting of a Tl+ion and a nearby negative ion vacancy are suggested to be responsible for the observed luminescence decay. The changes in the decay characteristics after pretreatments are explained on the basis of the location of the centres in normal and distorted regions of the host lattice. 
  Reference    Z. Naturforsch. 33a, 1241—1242 (1978); received May 18 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1241_n.pdf 
 Identifier    ZNA-1978-33a-1241_n 
 Volume    33 
175Author    Siegfried HessRequires cookie*
 Title    Diffusion Controlled Effective Reaction Rate for a Surface Reaction with Orientational Selectivity  
 Abstract    The influence of the orientational selectivity of a chemical reaction on the diffusion controlled effective reaction rate is investigated theoretically for the following situation: Nonspherical molecules with random orientation are put into a chemically inert solution a t a plane which is a certain distance away from the parallel reaction plane. The reaction frequency at the surface shall depend on the orientation of the figure axis of a molecule relative to the normal of the reaction plane. With a special choice for the orientational dependence of the surface reaction, a continued fraction expansion is derived for the diffusion controlled effective reaction rate. This quantity is discussed and displayed graphically as function of the relevant parameters. 
  Reference    Z. Naturforsch. 33a, 1243 (1978); received July 26 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1243.pdf 
 Identifier    ZNA-1978-33a-1243 
 Volume    33 
176Author    Fritz TrösterRequires cookie*
 Title    Derivation of Phonon Assisted Auger Transition Probabilites in Semiconductors  
 Abstract    In this paper a theory developed by Stumpf [1] will be used in order to calculate Auger transi­ tion probabilities in semiconductors. The main feature of the calculations is the incorporation of the coupling of impurity electrons to the surrounding lattice by phonons, using dynamical elec­ tronic wave functions for impurity states. The final result is an expression for transition probabi­ lities, describing multiphonon assisted Auger transitions in semiconductors. 
  Reference    Z. Naturforsch. 33a, 1251 (1978); received July 3 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1251.pdf 
 Identifier    ZNA-1978-33a-1251 
 Volume    33 
177Author    W. RennRequires cookie*
 Title    Screening of Impurity Pseudopotentials in Polar Semiconductors  
 Abstract    I t is shown how the total pseudopotential of an impurity (and not its Coulomb potential only) is screened by the electronic and ionic polarization of the host crystal caused by the impurity it­ self. An atomic description of the host crystal and the static polarization is given by means of the dipolar model developed by Stumpf. The i '-centre in alkali halides is treated as an example to test the method. For actual calculations, the BSG pseudopotential is used. Numerical results of the absorption and optical ionization energies are presented. 
  Reference    Z. Naturforsch. 33a, 1261 (1978); received July 3 1978 
  Published    1978 
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 Identifier    ZNA-1978-33a-1261 
 Volume    33 
178Author    Clemens Aderhold, Franz Baumgärtner, Ernst Dornberger, Basil KanellakopulosRequires cookie*
 Title    Die Uran(IV)-Liganden Wechselwirkungen in den Paramagnetischen Tetra-und (Tris-Cyclopentadienyl) -Halogeniden  
 Abstract    The magnetic susceptibilities of the uranium tetrahalides and of the tris-cyclopentadienyl-uranium-halides were measured from 1 to 300 K by using a Faraday magnetic balance a t six applied magnetic fields between 3.50 and 13.1 kOe. I t is found th at these compounds do not obey a Curie-Weiß law. Their effective magnetic moments a t room temperature show maximally 70% of the moment calculated for the free U 4+-ion. By taking into account spectroscopic data the experimental magnetic susceptibilities can be described by using a modified Van Vleck theory. 
  Reference    Z. Naturforsch. 33a, 1268—1280 (1978); eingegangen am 17. August 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1268.pdf 
 Identifier    ZNA-1978-33a-1268 
 Volume    33 
179Author    S. Takamuku, B. Dinh-Ngoc, W. SchnabelRequires cookie*
 Title    Pulse Radiolysis of Tetraphenylcyclobutane in Hexamethylphosphoric Triamide Solution  
 Abstract    r-1, c-2, t-3, t-4-tetraphenvlcyclobutane (TPCB) was irradiated in dilute solutions of hexa­ methylphosphoric triamide (HMPT) with 20 ns pulses of 16 MeV electrons. Solvated electrons (e^iv) produced during the radiolysis of HMPT react with TPCB with k = (6 ± 1) • 109 1/mol s. Simultaneously with the decay of the optical absorption of the solvated electrons, the formation of the absorption of t-stilbene (at 300 nm) and that of stilbene radical anions (at 500 nm) was observed. Thus, it is concluded th a t TPCB is undergoing a dissociative electron attachm ent process + TPCB -> t-St + t-St" . The lifetime of a possible intermediate (TPCB") was estimated as being smaller than 10~9 s. The 100 eV yield of t-stilbene was determined as G(t-St) = 3.4. 
  Reference    Z. Naturforsch. 33a, 1281 (1978); received August 29 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1281.pdf 
 Identifier    ZNA-1978-33a-1281 
 Volume    33 
180Author    H. W. Drawin, J. RamRequires cookie*
 Title    Structure of the H el 43D, 3F-2 3P (X = 447.15 nm, X = 447.0 nm) Spectral Line Emitted from a Low-Pressure Linear Discharge  
 Abstract    The line profile of the H el line at X = 447.15 nm has been measured during the ionisation phase and during the afterglow of a condensed low-pressure helium discharge by means of a 10-channel spectrum analyzer having a channel width of 0.1 Ä. The temporal resolution was I.6 pis (e-folding time). The filling pressure ranged from one to twenty Torr. The same relative peak structure was observed during the plasma build-up phase and the afterglow, only the intensities of the peaks were different in the two cases. Our measured profiles are quite similar to those obtained under different experimental conditions by other authors who explained the structure as being due to Baranger-Mozer plasma satellites. In contrast to this we did not find any correlation between electron density and peak position, i.e. the interpretation as Baranger-Mozer plasma satellites has to be excluded. The wavelengths of a number of peaks agree well with already identified He2 molecular lines, and there are sufficient experimental indications to conclude th at the prominent part of the satellite structure originates from He2 molecular tran ­ sitions most of which have not yet been identified. 
  Reference    Z. Naturforsch. 33a, 1285—1293 (1978); received July 18 1978 
  Published    1978 
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 TEI-XML for    default:Reihe_A/33/ZNA-1978-33a-1285.pdf 
 Identifier    ZNA-1978-33a-1285 
 Volume    33 
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