Optical characteristics of radiation from N<Stack><Subscript>2</Subscript><Superscript>*</Superscript></Stack> dimers in a barrier discharge

The spectral and power characteristics of radiation of the second positive system of nitrogen (C ³Π _u → B ³Π _g ) in Ar-N₂ and Ar-N₂-Cl₂ mixtures excited by barrier discharge have been studied experimentally. Addition of argon to N₂ increased the radiation power by sixfold. In the triple mixture Ar-N₂-Cl₂ = 210/0.5/0.005, minor chlorine additions increased the intensity of the C ³Π _u → _B ³Π _g transition by 26% compared to Ar-N₂ mixtures. Radiation power density of 2.7 mW/cm² has been achieved. In both binary and triple mixtures, the second positive system of nitrogen was the major contributor to radiation, while the contributions of the fourth positive system of N ₂ ^* (D ³Σ _u ⁺ → B ³Π _g ), the Vegard-Kaplan transition of N ₂ ^* (A ³Σ _u ⁺ → X ¹Σ _g ⁺ ), and the D′ → A′ band of Cl ₂ ^* were negligibly small.     

A new emission band spectrum of sulphur

A new emission band system of S₂ has been obtained in the region λ 3050–λ 2670 when sulphur is excited in a 30 mc/S. high frequency discharge from a 1/2 kW oscillator. The bands appear single sharp headed and are degraded towards red. Analysis of these new bands as belonging to a single system has led to the following vibrational formula.ν=36624·7+428·5(v′+1/2)?3·45(v′+1/2)² ?699·2(v″+1/2)+3·2(v″+1/2)². This system disignated as (b?x) is tentatively assigned to the electronic transition¹∑ _u ⁺ ?¹∑ _g ⁺ . The¹∑ _g ⁺ (x) state is found as the common lower state of three of the far ultraviolet systems of S₂ recently reported byTanaka andOgawa.     

Untersuchung des „Auroral Afterglow“ und seiner Präparationsstadien

The intensity decay of negative bands of N ₂ ⁺ and of first positive bands of N₂ in the auroral afterglow has been measured. An explanation, seeming possible for the decay curves of the first ones is proposed. By this the intensity decay in the beginning of the afterglow at high ionic densities is determined by the recombination of N ₂ ⁺ with electrons. Later, the ambipolar diffusion of the charge carriers to the wall causes the time dependance. A value of the ambipolar diffusion coefficient in nitrogen, derived from the measurements is given by the relationD _a ·p ≈ 124cm² sec^?1 Torr. The temperature of the charge carriers is estimated to be 313? K. The intensity decay of the pos. group in the afterglow seems mainly to be due to the diffusion of metastable particles to the wall.     

Rotationstemperaturen von H2 bei Beschuß mit 15 keV-Elektronen

Rotational temperatures have been determined from the intensities of the vacuum ultraviolet H₂(2p ¹ Π _u →1s ¹ Σ _g ⁺ ) emission lines, excited by 15 keV electron impact. Their experimental values for the unperturbed 2p ¹ Π _d rotationallevels verify theoretical predictions, and show that the fast electron impact populates 2p ¹ Π _d out of the ground state byΔJ=0, analogous to the valid optical selection rule.     

Messung der Kernradiusdifferenzen von46Ti,48Ti und50Ti durch elastische Elektronenstreuung

Ratios of differential cross sections for elastic electron scattering from⁴⁶Ti,⁴⁸Ti and⁵⁰Ti have been measured at 29 MeV and 58 MeV. A partial wave analysis, carried out for static Fermi-type nuclear charge distributions, yields differences of the r.m.s. radiiR _m ofR _m ⁴⁸ ?R _m ⁴⁶ =(?0,00₅±0,02₇) fm andR _m ⁵⁰ ?R _m ⁴⁶ =(0,00₃±0,02₁) fm, if the skin thickness parameterz of the charge density is assumed to be constant. If allowance is made for a change inz ofΔz/z=±5% and ±10%, then the errors increase by ±0,01₃ fm and ±0,02₈ fm, respectively. This indicates a relatively small change in nuclear r.m.s. radii below the magic neutron number N=28.     

Emission properties of an atmospheric-pressure helium plasma jet generated by a barrier discharge

The emission properties of an atmospheric-pressure helium plasma jet generated by a barrier discharge in a capillary blown with helium are studied. The spectral composition of the radiation of the studied plasma jet and the spatial-spectral distribution of its intensity are investigated in detail. It is shown that the emission spectrum of the generated plasma jet outside the capillary consists mainly of electronic-vibrational transitions of the first negative system of ionized nitrogen molecules N ₂ ⁺ (B ²Σ _u ⁺ → X ²Σ _g ⁺ ) and the second positive system of neutral nitrogen molecules N₂(C ³Π _u → B ³Π _g ).     

Eine Modellvorstellung für das „Auroral Afterglow“ und das „Pink Afterglow“

Based on own measurements of the decay of light intensity and electron density, a simple model for the auroral afterglow and the pink afterglow is proposed. To a certain extent the model can account for the influence of pressure and tube diameter on the behaviour of the afterglow. The first decay of the electron density towards the first minimum seems not to be influenced by creation processes for electrons during 3 to 15 ms. Therefore, the first decay can be used to measure the neutralization processes of electrons and positive ions. At pressures lower than 3 torr the electrons are removed by ambipolar diffusion with a rate given byD _a ·p≈2100 torr·cm²·s^?1. From this value an electron temperature of about 7200 °K could be derived. Assuming that ambipolar diffusion will remain the dominant loss process the time dependence of the electron creation rate has been evaluated. At a pressure of 1,75 torr the maximum electron creation rate was 4·10¹² s^?1·cm^?3. At the same time the emission density rate of the first negative bands was found to be 2.7·10¹³ cm^?3 s^?1. During one decay process about five times more electrons are created than the initial number. To explain the proportionality found between the electron density and the emission of the first negative bands, it is assumed that the ions, presumable N ₂ ⁺ -ions, are repeatedly excited to theB ² Σ _u ⁺ -state by metastables.     

Ab initio calculation of transition dipole moments for transitions between valence states in oxygen molecules

Results of ab initio calculations of potential-energy curves for 20 singlet and 20 triplet valence states of oxygen with configuration interaction taken into account in the 6-31G basis are presented. Transition dipole moments of triplet-triplet (1³Π_g ← B ³Σ _u ^? , 1³Π_g ← A ³Σ _u ⁺ , 1³Π_g ← A′ ³Δ_u, B ³Σ _u ^? ← X ³Σ _g ^? , 2³Π_u ← 1³Π _g, 2³Σ _g ^? ← B ³Σ _u ^? , 1³Π_u ← X ³Σ _g ^? , 2³Π_u ← X ³Σ _g ^? , 2³Π _g ← A′³Δ_u, 3³Π_g ← A′ ³Δ _u, 2³Δ_u ← 2³Π_g, 3³Π_g ← B ³Σ _u ^? , and 2³Π_g ← A ³Σ _u ⁺ ) and singlet-singlet (2¹Σ _g ⁺ ← 2¹Π_u, 2¹Π_u ← 1¹Π ^g, ¹Π_u ← 2¹Δ_g, 1¹Π_g ← c ¹Σ _u ^? , ¹Π_u ← b ¹Σ _g ⁺ , 1¹Δ _u ← a ¹Δ_g, 2¹Π_u ← a ¹Δ_g, 2¹Δ_g ← 1¹Δ_u, ¹Π _u ← a ¹Δ _g, 1¹Π_u ← b ¹Σ _g ⁺ , 2¹Π_g ← 1¹Π_u, 2¹Π _g ← c ¹Σ _u ^? , 1¹Δ _u ← 1¹Π _g, f′Σ _u ⁺ ← b ¹Σ _g ⁺ , 2¹Σ _g ⁺ ← f ′¹Σ _u ⁺ , 3¹Π_g ← 1¹Δ_u) radiative transitions are calculated as functions of internuclear separation. The possibility of observing these transitions under experimental conditions is discussed.     

Dipole moment functions for electronic transitions from ion-pair states of the second tier of molecular iodine

The emission spectra caused by the transitions from the ion-pair states and f0 _g ⁺ and G1_g of the I₂ molecule are obtained by excitation of individual rovibronic levels of the molecule by the method of optical-optical double resonance. The emission spectra from the state F0 _u ⁺ populated due to collisions I₂(f) + I₂(X) are also measured. By modeling the experimental emission spectra, the dipole moment functions for the electronic transitions f _g ⁺ -B0 _u ⁺ , A0 _u ⁺ , and B″0 _u ⁺ ; G1_g-A0 _u ⁺ and B″0 _u ⁺ ; and F0 _u ⁺ -X0 _g ⁺ and a′0 _g ⁺ of the iodine molecule are reconstructed.     

Mass spectrometer studies of the ion composition in the pink afterglow

The time dependences of the ion number densities in the pink afterglow of nitrogen, as represented by the ion wall currents, have been measured. The ions were extracted through an orifice from a flow system and analysed by a quadrupol mass spectrometer. It has been found thatN ₂ ⁺ ions are dominating in the early afterglow. With the beginning of the ionization processN ₃ ⁺ and at pressure >6 TorrN ₄ ⁺ become the majority ions. The ratio of the number densities(N ₃ ⁺ )/(N ₂ ⁺ ) reaches a maximum during the increase of the ionization processes before the maximum is reached. This behaviour suggestsN ₃ ⁺ ions to be the primary ions created by the ionization processes. The time dependences of the ion number densities (N ₂ ⁺ ), (N ₃ ⁺ ) and(N ₄ ⁺ ) are found to vary similar, showing that the ions are strongly coupled by conversion processes. The conversion processes are discussed. In the maximum of ionization at a total pressure of 4.4 Torr the ratios of the number densities of the afterglow ions (N ₂ ⁺ )∶(N ₃ ⁺ )∶(N ₄ ⁺) are 1∶1.9∶0.64.     

Umladung und Ionisation beim Durchgang von leichten und schweren Wasserstoffionen durch leichten und schweren Wasserstoff

Charge exchange and ionisation cross-sections were measured for the interaction of H⁺, H ₂ ⁺ , D⁺ and D ₂ ⁺ ions with H₂ and D₂ in the energy range 1.5–30 keV. In contrary to earlier measurements showing no isotope effect for a given ion velocity the results were as follows:

1. a)
   The charge exchange cross-sections depend on the proportion of the ion massm ₁ and the mass of the target moleculem ₂. The cross-sections increase with increasingm ₂/m ₁.     
   
   

Pion-pion interaction andK 2x03C0;x03C0;x03C0;-decay

The enhancement of theK _2π ⁺ -decay compared to theK _2π ⁰ -decay is discussed on the basis of the\(|\mathop {\Delta {\rm I}}\limits^ \to | = \tfrac{1}{2}\)-rule. The enhancement factor is calculated by dispersion methods which yield an expression depending only on the phase shift of the two pion system in theJ=0,I=0,2 state. This expression has been studied in the framework of simple models for the two-pion interaction in order to obtain a survey of the possibilities for the cause of the anomalous large ratioK _2π ⁺ /K _2π ⁰ . Only characteristic cases have been considered and, as far as possible, experimental results of theπ-π-interaction are taken into account.     

Konversion der 238,6 keV-γ-Linie des ThB und Vergleich mit den Tabellen von Sliv und von Rose

The conversion ratiosK/L _I andK/L _II of the 238.6 keVγ transition of ThB have been measured with the new Heidelbergπ/2 √13Β-ray spectrometer. For this transition there are great discrepancies between the values as given bySliv andBand, and byRose. The experimental resultsK/L _I=5.96±0.26 andK/L _II=60.3±7.1 are in excellent agreement with the values ofSliv andBand.     

Untersuchung des Iridium-191m-Zerfalls

Theγ-radiation of the nuclear isomer Ir^191m (T _1/2=4.5 sec) has been investigated with the aid of a scintillation fast-slow coincidence-spectrometer. Theγ-rays of the 42 keV-transition have been measured for the first time. The conversion coefficient α of this transition was found to be α = 13500 ₊₂₁₁₀₀ ^?5200 in acceptable agreement with the value taken from the tables ofRose under the assumption of anE3-transition. Thus this assignment proposed earlier by other authors has been confirmed. TheK-conversion coefficient of the 129 keV-transition has been remeasured yielding α _K =2.32±0.06.     

Untersuchung eines Li-Cr-Ferrits mit Hilfe des Mößbauer-Effekts

The hyperfine-structure spectra of the 14.4 keVγ-ray of the nucleus⁵⁷Fe in the spinel type ferrite (Li ₀₅ ⁺ Fe _1.3 ³⁺ Cr _1.2 ³⁺ O ₄ ^2? ) have been measured through the use of the Mößbauer effect. These measurements were performed on powder samples at different temperatures between 88 °K and 633 °K. For the Fe³⁺ ions at both the tetrahedral (A) and octahedral (B) sites at 88 °K the effective magnetic fieldH at the Fe nuclei is the same and equal to 504±4 kG. The temperature dependence ofH _A however is different fromH _B . Application of an external magnetic field of 20 kG shows that the sign ofH _A is positive and the sign ofH _B is negative. As the temperature is increased a considerable broadening of the magnetic hfs-lines (and especially of the outer pair of lines) is observed. No theoretical discussion directly applicable to these measurements is as yet available. In the paramagnetic phase a well resolved doublet is obtained. It appears that this doublet must be interpreted as a quadrupole splitting.     

Spin-lattice relaxation of protons and deuterons in NH4NO3 and ND4NO3

The spin-lattice relaxation timesT ₁ were measured for protons and deuterons in polycrystalline NH₄NO₃ and ND₄NO₃. The investigation was carried out at temperatures between about 80°K and 430°K using the NMR pulse method. From the measured values ofT ₁ the activation energies for the reorientation motions of NH ₄ ⁺ and ND ₄ ⁺ ions below 200°K were calculated to be 2.07±0.11 kcal/mole and 2.56±0.23 kcal/mole, respectively. The quadrupole coupling constante ² Qq/h of the deuteron in ND ₄ ⁺ ion was found to be 194±30 kc/s.     

Spectral representation for singlet and triplet green's functions

Spectral representations of special Green functions are given explicitly. We consider the density correlation functionG ₂(x ₁ η ₁ x ₂ η ₂,x ₁ ⁺ η ₁ x ₂ ⁺ η′₂) and the functionG ₂(x ₁ η ₁ x ₁ ^? η₂,x ₂ η ₁ ^′ x ₂ ^? η ₂ ^′ Coupling the field operators Ψ^? (x, η), Ψ(x, η) to singlet and triplet operatorsA _{SMs TT3} (x), we obtain spectral representations for theseG-functions. The formulae derived may be of use when studying the system of equations for the Green functions, which describe many particle systems from a microscopic point of view.     

Meson baryon sum rules

The PCAC consistency condition, the Adler-Weisberger sum rule and the dispersion superconvergent sum rule have been saturated with resonance contributions only. Strangeness-changing currents and strangeness-conserving currents have been considered and compared. The results obtained also support PCAC for the strangeness conserving current. While in theπN case PCAC and the Adler-Weisberger sum rule are almost saturated with the famous N ₃₃ ^* resonance only, in the KN caseY ₁ ^* (1385),Y ₀ ^* (1405) andY ₀ ^* (1520) seem to be sufficient. The superconvergent sum rule works very well in the case ofπN scattering, including the contribution of twelve resonances. For KN scattering it can be neither established nor disapproved.