The high resolution infrared spectrum and laser Stark spectroscopy of thev8 band of propyne

The perpendicularv ₈ band lying in the 1000–1100 cm^–1 region has been studied from infrared and laser Stark, spectra. We were interested in the part of spectrum corresponding to the spectral range of the 9 m CO₂ laser lines. Assignments of rovibrational lines with J'<40 and K'<6 have been made. About 100 Stark resonances have been assigned to 12 rovibrational transitions. Effective molecular constants and dipole moment have been determined with high accuracy. A list of close resonances with CO₂ laser lines is given and may be used for optical pumping experiments.     

Low temperature Mössbauer spectra and magnetic ordering of lithiated ferric molybdate: Li2Fe2(MoO4)3

Powder x-ray diffraction, variable temperature magnetic susceptibility, and zero field Mössbauer spectroscopy measurements were used to characterize the new phase Li₂Fe₂ (MoO₄)₃. This material is obtained topochemically simply by the mixing of solutions of lithium iodide in acetonitrile with solid Fe₂(MoO₄)₃ at ambient temperature. Li₂Fe₂(MoO₄)₃ possesses the high temperature orthorhombic ferric molybdate $$\begin{gathered} Fe_2 (MoO_4 )_3 + 2LiI\xrightarrow{{CH_3 CN}}Li_2 Fe_2 (MoO_4 )_3 + I_2 \hfill \\ (solid)(solution)(solid)(solution) \hfill \\ \end{gathered}$$ structure. Guinier photographs were completely indexed in space group Pnca. Magnetic hyperfine splitting of the zero field Mössbauer spectrum below 12.5 K indicates a three-dimensional magnetically ordered state which susceptibility results show to be weakly ferromagnetic owing to probable canting of antiferromagnetically coupled sublattices.     

Field dependent critical fluctuations aboveT g in the ESR line width of the spin glassAgMn

The ESR of the spin glassAgMn (2.7 and 9.6 at %) has been investigated below and aboveT _g(0.1T _g<T<5T _g) at various microwave frequencies. The analysis yields:1) No explicit frequency dependence but strong magnetic field effects, inherent with ESR-experiments.2) Part of the excess line width is identified as critical spin fluctuations, following a power law. However, because of the presence of the applied field, the reduced temperaturet is not a good scaling variable. We choose the non-linear susceptibility X _s divided byH ², which scales as the order parameter susceptibility. The experiment yieldsW _ex(X _s /H ²) ^p ,p=0.42. From this we deduce z3.     

Contribution ofp-wave (3)+1 subamplitudes to4He binding energy and scattering observables below four-body breakup threshold

The four-body equations of Alt, Grassberger and Sandhas, in the form that the (2)+(2) subsystem amplitudes are treated by the convolution method, are solved for separable two-body interactions between nucleon pairs in the channels³S₁-³D₁ (t ₀₀ alone) and¹S₀. AllL=0 andL=1 (3)+1 subamplitudes are represented in a separable form using the energy dependent pole expansion. The contribution ofp-wave (3)+1 subamplitudes to the⁴He binding energy, threshold scattering observables and low energy cross sections forn ³Hn ³H,p ³Hep ³He,dddd andddp ³H reactions is studied for different two-body potentials.     

Separation and determination of volatile compounds in synthetic wine samples by gas chromatography using UV-visible molecular absorption spectrometry as detector

This paper shows the separation and determination of eight compounds containing the OH group (ethanol, pentanol, 3-methyl-1-butanol, hexanol, phenol, benzyl-alcohol, phenylethanol and geraniol) in synthetic wine by gas chromatography using UV-Vis molecular absorption spectrometry as detection system. All the parameters affecting the separation and determination were optimised using some methods of experiment design. The analytical characteristics of each compound were calculated and detection limits ranging from 2.3 to 74 mg l(-1) have been obtained.     

Parametric Excitation of the Electron-Acoustic Wave in a Multiply Ionized Plasma

Parametric excitation of the electron-acoustic wave (EAW) has been analysed using a hydrodynamical model. The plasma has been assumed to consist of multiply charged ions. The ratio (α) of the hotter ion concentration to that of the electrons is a sensitive parameter. The condition for the occurrence of the EAW is well satisfied for the smaller values of α. The growth rate of the instability gets enhanced by increasing α and the charge state of the hotter ions. The values of α can be varied within short range only.     

The magnetic hyperfine field of bromine in iron by NMR/ON

Nuclear magnetic resonance of⁸²Br oriented at low temperature in iron has been observed with a sample prepared by ion implantation atT<0.2 K. The asymmetric resonance signal can be decomposed in a broad background signal and a narrow line of FWHM=1.8 (4) MHz which can be attributed to⁸²Br in undisturbed substitutional sites of Fe. From the center frequency of this narrow line (B _ext=0)=201.86(13) MHz we derive the magnetic hyperfine field asB _hf(BrFe)=81.38(6) T. This value is considerably larger than the result of theoretical calculations.     

On the diffusion field in the neighborhood of two identical spheres

Summary Under steady state conditions the reduction in the diffusive flux into a sphere due the presence of a neighboring, identical sphere is calculated. Taking the flux into a sphere as 1 when the particles are at infinite separation, the flux decreases to a minimum value of 0.693 when the spheres are touching.

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Zusammenfassung Unter stationären Bedingungen wird die Abnahme des Diffusionsflusses in eine Kugel, bedingt durch eine benachbarte identische Kugel, berechnet.Wird der Diffusionsfluß in eine Kugel gleich 1 gesetzt, wenn die Partikel unendlich weit voneinander entfernt sind, so nimmt der Diffusionsfluß auf einen Minimalwert von 0,693 ab, wenn sich die Kugeln berühren.

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With 2 figures     

Particle shape in thixotropic aluminium and thorium molybdates gels

Summary Electron microscope examination of thixotropic aluminium and thorium molybdate gels shows that one hour after formation they are constituted by short fibrils of small axial ratio. The fibrils of the aluminium molybdate gels, with ageing at room temperature or with boiling, increase in diameter and length; the fibrous shape of the particles is maintained after two and a half years of ageing; all fibrils are crystalline by electron diffraction. The fibrils of the thorium molybdate gels, except in the gels containing hydrochloric acid, change with ageing at room temperature or with boiling, into plates of hexagonal, elliptical or rectangular profile; the fibrils and plates are crystalline and have the same electron diffraction pattern as the fibrils.This work was aided, in part, by grants from Conselho Nacional de Pesquisas and the Rockefeller Foundation.