Volume 31, Issue 3-4

The rotational spectra of three isotopic species of HNC have been observed in the millimeter wave region. In the case of the parent species, H 14 N 12 C, our measurement of the J = 1←0 transition unequivocally confirms the assignment of the U90.7 interstellar line to HNC. For the parent species the molecular constants obtained are B 0 = 45332.005(40) MHz and D 0 = 0.1019(50) MHz. Structural parameters derived from the ground state rotational constants of this linear molecule are r(H-N) = 0.987 (3) Å and r(N-C) =1.171 (4) Å.

A theory is developed in which the gravitational as well as the electromagnetic field is described in a purely geometrical manner. In the case of a static central symmetric field Newton’s law of gravitation and Schwarzschild’s line element are derived by means of an action principle. The same principle leads to Fermat’s law which defines the world lines of photons.

In the last few years the assignment of the optical phonons of LiNbO 3 to the different symmetry species was often changed. We therefore concluded that the relative intensities of the Raman lines must be re-examined. According to all elements of the Raman tensor, the fundamental spectra were recorded separately as far as possible. The relative intensities are listed within an error of 7 or 40 percent, each according to signal-to-noise-ratio and/or overlapping of nearby lines.

The quadrupole hyperfine structure of 85 Rb 127 I in the ground vibrational state was measured on the rotational transition J = 3→4 at 7.9 GHz. From the observed spectra the following quadrupole coupling constants were derived: 85 Rb : e q 0 Q = -40.40(30) MHz; 127 I : e q 0 Q = -59.89(30) MHz.

An optical method to monitor NO in air and exhaust gas has been investigated. In this method NO is excited by NO-γ-bands (A 2 Ʃ + ← X 2 II r ) generated in a microwave discharge and is detected by its subsequent fluorescence. Results indicate a linear detection range from 7.5 ppb to 1000 ppm in air using a time response of 10 s. Interferences from other atmospheric constituents are found to be small. The analysis requires only a small amount of sample gas.

The anharmonic force constants of ozone up to fourth order have been determined from recently published spectroscopic data of 16 O 3 and 18 O 3 . For the first time all experimental data presently available have been used in a least squares fit. Compared with recent work, the correct formula for the Darling-Dennison resonance parameter γ has been used now. The nonuniqueness of the solution is discussed. In addition, isotopic rules for various spectroscopic parameters are derived.

Hole currents are observed by illuminating 2,3 DN single crystals with 347 nm and 337 nm. The probability of generating free holes is a function of temperature and electric field-strength. In the cleavage plane of the crystals the mobility does not depend on the direction of the applied field and amounts to 2.6·10 -1 cm 2 /Vsec at room temperature, which exceeds the related value measured perpendicularly to the plane by a factor of four. The temperature-dependence of the mobility indicates shallow hole-trapping exspecially close to the surface. The trap depth is estimated to be 10 -2 eV. Temperature also influences the pulse shape, by which one can conclude that hole traps of 0.2 eV and ≲ 0.1 eV exist in a thin surface layer. Photocurrents exited with 347 nm increase stronger than quadratically with the electric field. Deep hole traps, being also restricted to the surface region of the crystals, are made responsible for this fact.

Deterministic nonperiodic flow (of “chaotic” or “strange” or “tumbling” type, respectively) was first observed, in a 3-component differential system, by E. N. Lorenz in 1963. A 3-component abstract reaction system showing the same qualitative behavior is indicated. It consists of (1) an ordinary 2-variable chemical oscillator and (2) an ordinary single-variable chemical hysteresis system. According to the same dual principle, many more analogous systems can be devised, no matter whether chemical, biochemical, biophysical, ecological, sociological, economic, or electronic in nature. Their dynamics are determined by the presence of a “folded” Poincaré map. Under numerical simulation, the proposed chemical system provides an almost ideal illustration to the underlying dynamical prototype, the “3-dimensional blender”. Thus, continuous Euklidean dynamics (and with it chemical kinetics) proves to be of equal interest in studying chaos as discrete dynamical systems already have.

The high-field first and second order Zeeman effect has been observed in Ethyleneoxide in order to determine the sign of the electric dipole moments from the g-values of different isotopes. The experimental data indicate that in Ethyleneoxide the negative end is at the Oxygen while in Pyridine the result is not conclusive. The effect of vibrations is discussed in some detail and it is concluded that the vibrational dependance of the g-values should be accounted for if the sign of the dipole moment is determined from Zeeman data (at least if H ↔ D substitutions are involved).

Measurements of R and Q branch a-type pure rotational transitions in the frequency range from 8 GHz to 220 GHz are reported for ketene-d 1 and ketene-d 2 . The microwave and millimeter wave transitions were analysed in terms of Watson’s reduced Hamiltonian, including the sextic terms H KJ and H JK . The values of the inertial defect and the τ defect obtained from the centrifugal distortion analysis are in accord with the planar model for the ketene molecule.

Molecular alignment in the nematic phase of p-methoxy benzylidene p′-n-butylaniline (MBBA) in the presence of electric and magnetic fields is investigated. The relative effectiveness of electric and magentic fields on the nematic liquid crystal MBBA is discussed. In the dielectric regime it is found that the threshold fields for chevron formation are considerably different from the threshold fields for inducing changes in the dielectric constant.

Measurements of the molar heat capacity in the quasi binary system MgCu 2 -MgNi 2 from 1.5 to 4.2 K have been made in order to calculate the electronic specific heat. According to previous investigations in other alloy systems (Laves phases) the Sommerfeld model for free electrons does not hold. The shape of the electronic specific heat function versus alloy composition is comparable to that of the susceptibility and in poorer agreement with the hydrogen solubility. Iron impurities in some alloy samples caused an anomalous temperature dependence of the heat capacity.

The abundance and isotopic composition of the noble gases were measured in three Spring-field specimens identified by the Denver Museum of Natural History with numbers 7029, 379.13 and 6040. The latter specimen contains more cosmogenic noble gas isotopes than the other two specimens and the abundance pattern of trapped noble gases in specimen 6040 is distinct from that in the other two specimens. Specimen 7029 contains about seven times as much radiogenic 40 Ar and about four times as much radiogenic 129 Xe as does specimen 379.13. These results indicate that the three specimens did not come from a single meteoroid.

The complex formation between Cu (I) Cl and Cl − was investigated in a 1 M HClO 4 ionic medium at 22 °C. In saturated CuCl(s) - Cl − -solutions over the concentration range 0 - 0.25 M Cl − the only complexes observed are CuCl 2 − and CuCl 3 2− . The complex constants for the formation of these complexes are logβ 11 = −1.31 and logβ 12 = −1.6 respectively. The UV-absorption spectra of CuCl 2 − and CuCl 3 2− were determined in the wavelength region 220 -370 nm. The absorption of CuCl 2 − is characterized by a strong band λ max < 200 nm (ε >2.7 · 10 3 ) together with a weak band having λ max = 230 nm (ε = 0.7-10 3 ). The spectrum of CuCl 3 2− is composed of two bands with λ max = 230 nm (ε = 4.7 · 10 3 ) and λ max = 276 nm (ε = 6.1 ·10 3 ).

In thin nematic films the director field n may only depend on z, the normal to the film plane. There are two stable configurations with less than all three types of deformation present, the pure twist and the pure splay-bend. For the pure twist under the additional influence of an external field normal to the twist plane the range of stability is well known already. For the pure splay-bend the critical equation is derived here under the additional influence of an external field normal to the splay-bend plane. It comes out as an eigenvalue problem which can be solved using Ritz’ method. Numerical solutions are presented for K 1 = K 3 .

Measurements of the temperature behaviour of the transverse relaxation of the protons of water molecules in native potatoe starch show two sorption states and an exchange of protons between these states. From model calculations of Woessner and Zimmermann the occupation of the states and the exchange rate can be evaluated. The portion of more tightly bound water molecules comes out to be about 17%. The energy of activation of the exchange decreases with increasing water content and lies with values in the range of 26 to 31 kJ/mol distinctly below the values observed usually for proton-exchange processes in similar systems.

A comparison was made between electron densities determined from the emission coefficient of the continuum radiation and from Stark broadening of line profiles using a wall stabilized pulsed arc plasma with electron temperature T = 38 000 K and electron density from 2 × 10 22 m −3 to 3.5 × 10 22 m −3 . The measured peak separation in the profiles of the He I lines 447.1 nm and 492.2 nm was consistent with that predicted by G.B.K.O.- and B.C.S.-theory and agrees with the experimental results from Bötticher, Roder, and Wobig. The measured halfwidth of the He I 501.6 nm line agrees with the results from Kusch and shows a discrepancy to the G.B.K.O.-theory by a factor about 1.7. The results for the Stark broadening halfwidth of the He II lines 468.6 nm and 320.3 nm lie between the values from G.K.S.-and K.G.-theory.

A computer program for following the trajectories of high energy ions in an fcc-lattice has been written to evaluate the reflection rate of high energy ions with grazing incidence to (001)- and (111̅)-Au-surfaces. The calculation yields a rapid decrease of the reflection rate for penetration directions close to low-index atomic planes. It can be shown that this result is caused by channeling of the ions between the atomic planes.

An improved two-center model has been used to describe the elastic scattering potentials for the collision of identical nuclei. The macroscopic-microscopic approach includes liquid drop (LD) deformation energies, shell corrections and pairing energy corrections. As basis for the microscopic part a two-center shell model has been used with a Hamiltonian including a Thomas-type spin-orbit potential and an l 2 correction term. The model is applied to the sudden and adiabatic type of scattering process, including a compression energy term in the LD part for the former case. Results are given as potential energy surfaces for the adiabatic scattering process and potential energy curves for the sudden scattering process.

In a previous paper the application of the LCAO interpolation method to crystal electrons in homogeneous magnetic fields of moderate strength has been described. In the present paper this method is tested for a crystal type which is of general interest. A simple model of the valence band of Germanium is constructed and the highest energy levels are calculated. The magnetic field is assumed in [001] direction. The results can be compared with the Luttinger-Kohn results.

95 Mo and 97 Mo Fourier transform NMR studies of several alkali molybdate solutions in H 2 O and D 2 O are reported. The Larmor frequency of the molybdenum nuclides is remarkably dependent on the solute and the solvent. In potassium molybdate the chemical shifts of 39 K were observed. The ratio of the Larmor frequencies of 95 Mo and 39 K was measured with high accuracy in a 2.6 molal solution of K 2 MoO 4 in H 2 O. From this value a nuclear magnetic moment of 95 Mo and 97 Mo in the molybdate ion was derived using the concentration dependencies of the Larmor frequencies of 39 K and 95 Mo and the ratio of the Larmor frequencies of 97 Mo and 95 Mo. In solid Ag 2 MoO 4 and metallic molybdenum the 95 Mo and 97 Mo NMR signals were detected; line widths and shifts are given.

The ground state rotational spectra of 80 Se and 78 Se species of the hexadeutero dimethyl selenide have been measured in the region from 5 to 40 GHz. In both the cases, rotational and centrifugal distortion constants have been determined by a least square fit to about thirty transition frequencies. For the (CD 3 ) 2 80 Se molecule, fourteen rotational transitions in the excited torsional states ṽ = l 1 , and ṽ = l 2 were also recorded, out of which nine appeared as well resolved triplets. The potential barrier parameter V 3 and the angle a between one of the ‘top axes’ and the ‘b axis’ have been determined by a least square fit of the mean value of the observed splittings in the ṽ = l 1 and l 2 states. The methyl top moment of inertia Iα was kept fixed at 6.35 amu Å 2 , which is half of the observed inertia defect in the molecule.

The non L.T.E. (local thermodynamic equilibrium) properties of optically thin and thick quasistationary oxygen plasmas have been calculated for the temperature range k T = 0.5 - 1.5 eV and for the electron density interval 10 8 - 10 16 cm -3 , by using the collisional-radiative model of Bates, Kingston and McWhirther. The results include 1 the coefficients r 0 (i) and r 1 (i), which represent the contribution to the population density of the ith quantum level from the continuum and from the ground state, respectively 2 the values of α and S, which are the collisional-radiative recombination and ionization coefficients, respectively. The accuracy of the present results is discussed in connection with the adopted plasma model and with the selection of the collisional cross sections for forbidden and allowed transitions. A discussion is also presented of the influence of the two low lying excited states of oxygen atoms (i.e. the states 2p 4 1 D, 2p 4 1 S) on the non L.T.E. properties of these plasmas. A satisfactory agreement is found with the calculations of Julienne et al. and with the experimental results of Jones.

The rotational Zeeman effect of FClCO is reported. The Chlorine nuclear g I -factor, the molecular g-factors, g aa , g bb , and g cc , and the magnetic susceptibility anisotropics, (2 χ aa - χ bb - χ cc ) mole and (2 χ bb - χ cc - χ aa ) mole, are obtained from the spectrum. Some derivative molecular quantities are calculated.

The rotational spectra of GeS and GeSe were measured in the frequency range of 66 GHz to 110 GHz with high precision. The breakdown of the Born-Oppenheimer approximation was observed for the rotational constant yol. With the known molecular 37-factor and the electric dipole moment the adiabatic part of the Born-Oppenheimer correction can be extracted from the primary observa-tion on y01. The adiabatic correction is very similar in both molecules but differs from the results in the earlier measurements on PbS.

The ten-term high temperature expansion calculations by Baker et al. (1967) for the d = 3, S = 1/2, cubic lattice Heisenberg models have been investigated numerically. Critical values based on the ten-term series were unreliable, however graphical extrapolation yielded critical values with a consistent q dependence among the various results for the sc, fcc, bcc, FM, and AFM models. The short range order, as measured by (S ∞ - S c )/R, is greater for the AFM models than for the FM model. The estimate of 0.35 ± 0.02 for (S ∞ - S c )/R of the sc-AFM model agrees with previous experimental work on CoBr 2 · 6 H 2 O and CoCl 2 · 6 H 2 O. Results are presented on the slow convergence of the high temperature expansions. Extrapolation of the series is needed for ε<0.1. Higher order corrections to the T −2 term are needed for T/T c <5. The critical values for the I(1/2) and H(1/2) models were interpolated to predict critical values for the sc and bcc XY(1/2) models.

Energies of y-rays from the radioactive decay of 57 Co, 60 Co, 137 Cs, 152 Eu, 153 Sm and 198 Au have been measured relative to the 411.794 keV γ-ray standard from the decay of 198 Au. The relative accuracy of the measurement is between 1.7 × 10 -5 and 1.0 × 10 -5 for E γ <900 keV.

Elastic and thermoelastic constants of cubic Y 3 Fe 5 O 12 -, Nd 3 Ga 5 O 12 -, and Sm 3 Ga 5 O 12 -garnets are measured hy ultra-sonic methods. The small differences of the elastic properties within the group of gallium garnets are nearly quantitatively described by the r −4 -rule, thus indicating the dominant role of ionic bonds. These garnets exhibit a similar thermoelastic behaviour. A slight but significant depression of the elastic constants is observed in Y 3 Fe 5 O 12 .

Q values are reported for (d, t) reactions on all the stable isotopes of zirconium. The neutron separation energies of 94 Zr and 96 Zr differ greatly (by 27.5 and 22.1 keV, respectively) from the values in the 1971 Atomic Mass Evaluation. These results combined with those from other authors seem to indicate that the 1971 values for the masses of 93 Zr and 95 Zr are in error.

The differential elastic cross sections for K + - Ar, Kr and Xe were measured in the energy range from 2.2 eV to 5.0 eV in the laboratory system and compared with those predicted by the theory of Kim and Gordon. The experimental well depths are smaller than predicted by this theory.

The interference function from liquid antimony at 600 °C, obtained by Waseda and Suzuki, has been reproduced using a model based on two hard sphere interference functions (packing density, 0.41 diameters 3.11 Å and 2.33 Å). Agreement obtained using the model is better than that existing between various independent diffraction measurements.

We have observed extremely sharp Doppler-free resonances in the measurement of molecular lifetimes of ex-cited states in the low pressure gas-phase of naphthalene. These resonances are seen at extremely low magnetic fields and have a width of only 3 Gauss. Their extreme sharpness of 2.8 × 10 −4 cm −1 is within a factor of 2 of the natural width of the radiationless transition, and some 130 fold below the Doppler width of the state considered. Such sharp resonances should provide unique insights into the states and dynamics of radiationless processes. They are probably due to sharp field dependent changes in the non-radiative coupling strength of the spin-orbit transition into the triplet.