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61	Author	G. Bestmann, H. Dreizler, H. Mäder, U. Andresen	Requires cookie*
	Title	Experiences with a Ku-Band Microwave Fourier Transform Spectrometer
	Abstract	The construction of a Ku-band microwave Fourier transform spectrometer is described in detail. The optimal cell length, sensitivity and resolution is discussed. Some sample spectra of SO2 and OCS isotopes are given.
	Reference	Z. Naturforsch. 35a, 392—402 (1980); received February 12 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0392
	Volume	35

62	Author	W. Urland	Requires cookie*
	Title	Über das magnetische Verhalten von Cs 2 MHoF 6 (M = Na, K, Rb)
	Abstract	The magnetic behaviour of CS2MH0F6 (M = Na, K, Rb) has been studied in the temperature range between 3.2 and 251.3 K. The magnetic data are interpreted by means of a previously developed model in which the influence of the crystal field is theoretically described by the angular overlap model. Values of the angular overlap parameters ea(R) and en(R) cannot be determined unequivocally. The energy values of the crystal-field levels of the 5 Is ground state are calculated.
	Reference	Z. Naturforsch. 35a, 403—407 (1980); eingegangen am 1. März 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0403
	Volume	35

63	Author	Yasuyuki Ishikawa	Requires cookie*
	Title	Closed Shell Hartree Theory with Orthonormal Orbitals
	Abstract	A natural orbital multiconfigurational SCF formalism has been applied to the closed shell Hartree theory with orthonormal orbitals. A prescription is given for constructing a single, one-electron Hamiltonian with which one can determine all the occupied orbitals. The formalism is suited to the matrix formulation of the orthogonalized Hartree theory for polyatomic systems.
	Reference	Z. Naturforsch. 35a, 408—411 (1980); received January 8 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0408
	Volume	35

64	Author	K. N. Swamy, P. C. Wankhede	Requires cookie*
	Title	Optimised Cluster Theory for the Triangular Well Potential
	Abstract	The optimised cluster theory of Andersen and Chandler has been applied to calculate the radial distribution functions of a triangular well fluid with the width a the hard sphere diameter The results agree well with Monte Carlo Calculations of Card and Walkley.
	Reference	Z. Naturforsch. 35a, 412—414 (1980); received December 24 1979
	Published	1980
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	Identifier	ZNA-1980-35a-0412
	Volume	35

65	Author	Edmund Fischer, Ivan Botskor	Requires cookie*
	Title	The Relative Orientation of the Total Dipole Moment in the N-cis Lone-Electron-Pair-Trans Isomer of Allylamine
	Abstract	The dipole moment of the doubly deuterated species (CH2=CH—CH2—ND2) of N-cis Lone-electron-pair isomer of allylamine has been measured. The "isotope pulling elfect" has been used to determine the relative orientation of the total dipole moment with respect to the principal axes in the normal species. The possible effects of large amplitude motions on the observed effective dipole moments are discussed.
	Reference	Z. Naturforsch. 35a, 415—417 (1980); received February 29 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0415
	Volume	35

66	Author	I. M. Brinn	Requires cookie*
	Title	Haloalkane-Aromatic Complexes in the Ground and Excited States Molecular Orbital Calculation
	Abstract	CNDO/2 calculations have been carried out on a series of haloalkane-aromatic 1: 1 complexes in the ground and first excited singlet states and one 2 : 1 complex in the ground state. Calculated stabilities agree very well with reported experimental results for the ground state. Our calculations indicate that the substituent effect on complex stability in excited states will be the opposite of that found for the ground state.
	Reference	Z. Naturforsch. 35a, 418—422 (1980); received January 30 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0418
	Volume	35

67	Author	0. Odawara, JanC T Kwak, J.A A Ketelaar	Requires cookie*
	Title	Diffusion Coefficients of Rb + and Cs + Ions in Molten Nitrate Systems
	Abstract	The tracer diffusion coefficients of 86 Rb and 137 Cs ions in the molten (Li-Na)N03, (Li-K)N03, (Li-Rb)N03, and (Li-Cs)N03 systems have been measured by means of a paper strip method. Results from the paper strip method in some pure nitrates are compared with the results from capillary and optical interferometric methods. With increasing concentration of LiN03, the diffusion coefficients at 350°C are found to decrease in the (Li-Na)N03 system and to increase in the (Li-K)N03, (Li-Rb)N03, and (Li-Cs)N03 systems. For 86 Rb in (Li-K)N03 an increase is followed by a decrease. These findings are discussed by taking into consideration the free space in the solvent system and the ionic interaction between the diffusing and the surrounding ions.
	Reference	Z. Naturforsch. 35a, 423—427 (1980); received November 26 1979
	Published	1980
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	TEI-XML for	default:Reihe_A/35/ZNA-1980-35a-0423.pdf
	Identifier	ZNA-1980-35a-0423
	Volume	35

68	Author	Walter Fabian	Requires cookie*
	Title	Versuche zur Berechnung der Fluoreszenzspektren organischer Farbstoffe
	Abstract	Attempts to Calculate the Fluorescence Spectra of Organic dyes Within the scope of the PPP-approximation a ^-variation procedure is used to calculate the fluorescence spectra of some organic dyes and to estimate geometry changes upon excitation into the fluorescent state.
	Reference	Z. Naturforsch. 35a, 428—430 (1980); eingegangen am 13. Februar 1980
	Published	1980
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	TEI-XML for	default:Reihe_A/35/ZNA-1980-35a-0428.pdf
	Identifier	ZNA-1980-35a-0428
	Volume	35

69	Author	Peter Scharfenberg, Bela Rozsondai, Istvän Hargittai	Requires cookie*
	Title	Conformation and Structure of Ethylbenzene in the Vapour Phase
	Abstract	The molecular structure of ethylbenzene has been studied by gas electron diffraction. Experi-mental intensities and radial distribution are well reproduced by an average structure with r = 70(3)°, where r is the angle between the C—C—C(H3) plane and the ring plane, mean (rg) bond lengths (C-C)phenyi = 139.9(3) pm, Cphenyi-C(H2) = 152.4(9) pm, C(H2)-C(H3) = 153.5(12) pm, C—H = 109.4(4) pm, and bond angle C-C-C(HS) = 111.8(15)°. (Estimated total errors are parenthesized.) An also acceptable perpendicular model (r = 90°) is accompanied by very large vibrational amplitudes, while the coplanar conformation (r = 0°) is excluded. Mixtures of conformers fit the experimental data as well. The barrier to rotation of the phenyl group is estimated from the average structure to be about 7 kJ mol -1 . According to CNDO/2 calculations, only the perpendicular form is stable. The results of a geometry optimization are shown.
	Reference	Z. Naturforsch. 35a, 431—436 (1980); received January 5 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0431
	Volume	35

70	Author	W. Rehder	Requires cookie*
	Title	When do Projections Commute?
	Abstract	Necessary and sufficient conditions for commutativity of two projections in Hilbert space are given through properties of so-called conditional connectives which are derived from the conditional probability operator PQP. This approach unifies most of the known proofs, provides a few new criteria, and permits certain suggestive interpretations for compound properties of quantum-mechanical systems.
	Reference	Z. Naturforsch. 35a, 437—441 (1980); received November 17 1979
	Published	1980
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	Identifier	ZNA-1980-35a-0437
	Volume	35

71	Author	D. Boucher, A. Dubrulle, J. Demaison	Requires cookie*
	Title	Microwave Spectrum of Ethyl Iodid: Internal Rotation Analysis
	Abstract	The rotational spectra of the first excited state of the methyl torsion and the CCI-in plane deformation of CH3CH2I have been studied. A Coriolis interaction between these two modes has been found. Splittings of transitions in the first excited torsional state show that the barrier hindering internal rotation of the methyl group is 3.62 kcal/mole. This value agrees quite well with the value previously reported from Raman studies. It is internally consistent and similar to the other ethyl halides. It was empirically found [1] that the methyl bar-rier in substituted ethanes CH3CH2X slightly in-creases when the electronegativity of the substituent X decreases. Consequently the barrier in ethyl iodide would be expected to be greater than in ethyl fluoride where V3 = 3.30 kcal/mole [2] and of the same order of magnitude as in ethyl bromide: V3 = 3.57 kcal/mole [3]. From a microwave study it was in fact shown that V3 = 3.22 kcal/mole [4], somewhat lower than expected from the above con-siderations. On the other hand a Raman investiga-tion in gas phase [5] has given V3 — 3.67 kcal/mole, which is considerably higher than the value pre-viously reported from microwave studies but in good agreement with the values found for the other ethyl halides. To clear up this discrepancy we have reinvestigat-ed the microwave spectrum of CH3CH2I. The spectra were recorded in the region from 5 to 80 GHz with a conventional microwave spectrometer employing 25 kHz Stark-modulation. For the high resolution measurements a 8 m-absorption cell was used, the sample pressure was 5 m-Torr and the temperature approximately — 50 °C. The analysis of the ground state spectrum is reported elsewhere [6].
	Reference	Z. Naturforsch. 35a, 442—446 (1980); received February 29 1980
	Published	1980
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	TEI-XML for	default:Reihe_A/35/ZNA-1980-35a-0442.pdf
	Identifier	ZNA-1980-35a-0442
	Volume	35

72	Author	H. Jena, W. Kreische, H. U. Maar, H. Niedrig, K. Reuter, B. Wrobel	Requires cookie*
	Title	Magnetic and Quadrupole Relaxation in Aqueous BeF2-Solutions
	Abstract	In aqueous BeFä-solutions of different concentrations and therefore different viscosities the magnetic relaxation time T\ was measured as a function of the viscosity over a wide range by pulsed NMR-technique. For small viscosities a linear dependence of T\ on the viscosity was observed as predicted by theoretical calculations. Since the ground state spin of 19 F is I = 1/2, the quadrupole moment vanishes. For observing quadrupole relaxation of the F-nuclei, one has to use an excited level. With the time differential perturbed angular distribution method (TDPAD) we observed the quadrupole relaxation time Tnei of 19 F in aqueous BeF2-solutions.
	Reference	Z. Naturforsch. 35a, 447—452 (1980); received January 18 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0447
	Volume	35

73	Author	Ivan Gutman	Requires cookie*
	Title
	Abstract	Three graphic polynomials of annulenes and radialenes are examined, namely the matching polynomial, the characteristic polynomial of the Hückel graph and the characteristic polynomial of the Möbius graph. Several relations between them are obtained. These six polynomials and their zeros are mutually closely related.
	Reference	Z. Naturforsch. 35a, 453—457 (1980); received September 13 1979
	Published	1980
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	Identifier	ZNA-1980-35a-0453
	Volume	35

74	Author	Ivan Gutman	Requires cookie*
	Title	Note on a Topological Property of the HOMO-LUMO Separation
	Abstract	The effect of cycles on the HOMO-LUMO separation of alternant conjugated hydrocarbons is examined. A general topological regularity is established, namely that (4m -f 2)-membered con-jugated circuits increase and (4w)-membered conjugated circuits decrease the HOMO-LUMO sep-aration. Möbius cyclcs exhibit an opposite effect. In recent years a graph theoretical technique was developed, which enabled one to analyse and partially understand the dependence of the rr-elec-tron properties of conjugated molecules on molec-ular topology [1]. The HOMO-LUMO separation (i.e. the difference between the energy of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO)) belongs among those ^-electron characteristics of a conjugated system, for which the graph theoretical approach was not very successful. The previously obtained results about the topological properties of the HOMO-LUMO separation are rather limited [2—4]. In the present paper we offer a general topological rule which elucidates the effect of cycles on the HOMO-LUMO separation of alternant conjugated hydrocarbons. An auxiliary graph theoretical polynomial According to the Sachs theorem [1, 5] tho characteristic polynomial of a graph G (with n vertices) is calculated as
	Reference	Z. Naturforsch. 35a, 458—460 (1980); received September 13 1979
	Published	1980
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	Identifier	ZNA-1980-35a-0458
	Volume	35

75	Author	0. M. Gradov, L. Stenflo	Requires cookie*
	Title	of Electromagnetic Radiation
	Abstract	A beam of electromagnetic radiation can generate mag-netic fields in plasmas. It is shown that those fields grow significantly when the incident radiation is sufficiently strong. We obtain expressions for the characteristic time of the growth of the fields as well as for their spatial distribution and point out a possible mechanism, which can lead to the formation of a quasi-stationary state. The maximum value of the magnetic field strength is estimated
	Reference	Z. Naturforsch. 35a, 461—463 (1980); received January 23 1980
	Published	1980
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	TEI-XML for	default:Reihe_A/35/ZNA-1980-35a-0461_n.pdf
	Identifier	ZNA-1980-35a-0461_n
	Volume	35

76	Author	AlainJ P Alix, Erling Rytter	Requires cookie*
	Title	and Momenta
	Abstract	The fundamental definitions of the Total Energy and of the Vibrational Total Energy Distributions are presented in details in terms of either symmetry coordinates, or gener-alised symmetry forces, or generalized symmetry coordinates. This, give now a uniform tool for physicists and chemists in the field of characterisation of the normal vibrational modes of polyatomic molecules. The definitions of the Total Energy Distributions, hereafter abbreviated as TED, have been the sub-ject of many works in recent years [1—9]. Several of the published papers present different aspects of the same fundamental concepts formulated in different words and notations, and in some cases it may seem that there are contradictory discussions and interpretations. We feel that it is necessary now to clarify the situation in order to give a uni-form tool for physicists and chemists in the field of characterisation of the normal vibrational modes of polyatomic molecules. This communication principally deals with fundamental definitions. In particular, the deriva-tion of the TED with symmetry forces as an alternative basis to symmetry coordinates is given, and the possibility of using momenta is introduced. Further comments on the TED-method will be found elsewhere [9]. TED in Terms of Contributions from Symmetry Coordinates Summation of the standard formulae [10] for the potential and kinetic energies in terms of symmetry coordinates, Si, and velocities Si, yields the total * Author to whom all correspondence should be addressed.
	Reference	Z. Naturforsch. 35a, 464—465 (1980); received November 12 1979
	Published	1980
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	Identifier	ZNA-1980-35a-0464_n
	Volume	35

77	Author	A. Kawski, J. Kukielski, P. Bałuk, M. Lenczewska	Requires cookie*
	Title	Anisotrope Fluoreszenz langgestreckter Moleküle in Lösungsmitteln unterschiedlicher Viskosität
	Abstract	The Anisotropie Fluorescence of Prolate Molecules in Sol-vents with Different Viscosities The emission anisotropics (r) of the fluorescence of the prolate molecules (whose emission transition moments are parallel to the long axis) 4-dimethylamino-4'-cyanostilbene, 4-methoxy-4'-nitrostilbene, 4-dimethylamino-4'-diphenylphos-phinoxidstilbene, 4-dimethylamino-4'-bromstilbene and p-bis[2-(5-a-naphthyloxazolyl) ] -benzene in solvents of different viscosities {rj) have been studied. Also for these substances the non-linear dependence of 1/r on Tjrj was confirmed. This non-linearity in the low viscosity range can be ex-plained by the assumption that the prolate luminescent molecules perform irregular rotational motions within a solid angle smaller than 90°. Effective volumes and rota-tional relaxation times for the different molecules in the different solvents were obtained. Diese Arbeit bringt weitere experimentelle Daten über die anisotrope Fluoreszenz folgender lange-streckter Moleküle in Lösungsmitteln unterschied-licher Viskosität: 4-Dimethylamino-4'-cyanoslilben (DCS), 4-Methoxy-4'-nitrostilben (MNS), 4-Dimethylamino-4'-diphenylphosphinoxidstilben (DDPS), 4-Dimethylamino-4'-bromstilben (DBS) und
	Reference	Z. Naturforsch. 35a, 466—467 (1980); received February 29 1980
	Published	1980
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	TEI-XML for	default:Reihe_A/35/ZNA-1980-35a-0466_n.pdf
	Identifier	ZNA-1980-35a-0466_n
	Volume	35

78	Author	G. Döge, R. Arndt, H. Buhl, G. Bettermann	Requires cookie*
	Title	Der Einfluß lokaler Konzentrationsfluktuationen in binären flüssigen Mischungen von CH3I und CDCI3 auf das Profil von Molekülschwingungs-Banden
	Abstract	The Raman band shapes of of CDC13 and CH3I in the pure liquids and their mixtures are studied. The CH.,1 mode shows a broadening in the mixtures with a maximum at a mole fraction of about 0.5, whereas the band of CDC1, shows a splitting in the mixture. The different behaviour of the two Raman bands is discussed briefly. Yon Bondarev und Mardaeva [1] sowie Fujiyama u. a. [2] wurde anhand IR-spektroskopischer Unter-suchungen gezeigt, daß in binären flüssigen Mischun-gen immer dann deutliche zusätzliche Verbreiterun-gen von Molekülschwingungsbanden bei mittleren Konzentrationen auftreten, wenn sich die Anregungs-frequenz einer bestimmten Normalschwingung mit zunehmender Verdünnung der betr. Komponente stark verschiebt. Dieser Befund wurde als Anzeichen dafür gedeutet, daß die individuellen schwingungs-angeregten Moleküle eine Schwingungsfrequenz be-sitzen, die nur von der Zusammensetzung der näch-sten Nachbarschaft derselben abhängt und nicht die mittlere makroskopische Zusammensetzung der Mi-schung widerspiegelt. Diese Vorstellung widerspricht zwar der älteren KBM-Theorie [3, 4], steht aber im Einklang mit der Annahme, daß nicht allzu weitrei-chende intermolekulare Wechselwirkungen für die Verschiebung der Molekühlschwingungsfrequenzen verantwortlich sind. Arndt u.a. [5] haben darauf hingewiesen, daß man solche Effekte besser raman-spektroskopisch untersucht, weil dann die Möglich-keit gegeben ist, die Umorientierungsverbreiterung der Banden zu eliminieren. Diese könnte die Resul-tate verfälschen, weil sie selbst konzentrationsabhän-gig ist. Bisher ging man bei der Interpretation der zusätzlichen Breite davon aus, daß in den Fällen, in denen die mittlere Zusammensetzung der 1. Koordi-nationsschale der makroskopischen Konzentration entspricht, die individuellen Zusammensetzungen
	Reference	Z. Naturforsch. 35a, 468—470 (1980); eingegangen 5. 2. 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0468_n
	Volume	35

79	Author	A. Dubrulle, J. Demaison, J. Burie, D. Boucher	Requires cookie*
	Title	The Millimeter Wave Rotational Spectra of Carbonyl Sulfide
	Abstract	The following rotational spectra of carbonyl sulfide have been accurately remeasured with a beam-absorption spectrometer: 16 0 12 C 32 S in the vibrational ground state and in the vibrational state 0 l 1 0. 16 0 12 C 34 S in the vibrational ground state. The ground state spectra of the following isotopic species have been measured with a video spectrometer: 17Q12C32S, 18012C32S, 16()13C32Sf 16012C33S, 16()12C36S, and 160 13 C34S. Our measurements have enabled us to improve the molecular constants notably for these cases.
	Reference	Z. Naturforsch. 35a, 471 (1980); received March 14 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0471
	Volume	35

80	Author	K. Dräger, R. Gerling	Requires cookie*
	Title	ESR-Untersuchungen an antiferromagnetischem CrN zum Einfluß der Temperatur auf die Austausch-Wechselwirkung
	Abstract	The ESR-behaviour of antiferromagnetic and almost stoechiometric CrN is thoroughly inves-tigated above its Neel-point. For polycrystalline samples a spectroscopic splitting factor g =1.965 and a differential line width AB = 56,7 mT is measured at room temperature. All resonance lines exhibit Lorentzian character to a high degree. In the temperature range between 300 K and 520 K the ESR-intensity can satisfactorily be described by a model of local ordering. Its binding energy is computed to be about AE = 500 ± 20 cm -1 . A more refined analysis shows a systematic change of AE with temperature and a discrepancy between the Neel-point TN and the temperature Ts characterizing a singular be-haviour of the line width AB. Apart from these deviations originating in a magnetic ordering of the fourth kind, the cluster-model gives an isotropic exchange between next nearest neighbours of Jz = — 33.2 cm -1 . This result is confirmed by molecular field computations.
	Reference	Z. Naturforsch. 35a, 475—482 (1980); eingegangen am 28. Februar 1980
	Published	1980
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	Identifier	ZNA-1980-35a-0475
	Volume	35

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