X-ray excited optical luminescence spectrum of Pr-doped YPO4

The X-ray excited optical luminescence spectrum of Pr³⁺ in YPO₄ was investigated. In addition to the sharp line f-f transitions involving the energy levels of the 4f² configuration of Pr³⁺ ion, the spectrum contains some broad groups of fluorescence lines in the ultraviolet and blue region. These groups of fluorescence are attributed to transitions from the lowest 4f^I5d state at 43050 cm^-1 to the 4f² levels of the Pr³⁺ion in YPO₄.     

Neutrino backgrounds in the Kolar Gold Field nucleon decay experiment

The neutrino events recorded in the Kolar Gold Field Nucleon Decay detector are analysed here. It is shown that there is good agreement between the observations and the estimates based on the intensities of atmospheric neutrinos and interaction cross-sections of neutrinos available from accelerator experiments. In the context of the search for proton decay, we show that the low energy (<2 GeV) neutrino events, which would provide the main background, are suppressed at thekgf site since it is situated near geomagnetic equator, where the geomagnetic cut-off rigidities are high. A comparison of the predicted characteristics ofv-induced events with thekgf observations shows that, within the statistical accuracy of the present data, the signal due to nucleon decay stands out distinctly within thev-induced background.     

Theβ- andγ-band systems of14NS and15NS

The spectra of¹⁴NS and¹⁵NS molecules are obtained in a 2450 mc./s. microwave oscillator discharge. Vibrational assignments of theβ- andγ-systems are studied in more detail. Several hitherto unrecorded bands are satisfactorily explained as belonging to higherv′,v″ levels in the Deslandres schemes of bothβ- andγ-systems. The observed isotope shifts (¹⁴NS-¹⁵NS) provide confirmatory evidence for the proposed vibrational analysis. In the case of theγ-system, thev′=2 level of the upper state appears to be strongly perturbed showing a shift of about 38 cm.^?1 from the expected position. In theβ-system, the isotopic shifts in the band-heads involving thev′=0 and 1 levels of the²Δ_5/2 of the upper state show small deviations from expected values. The reality of these small deviations is established beyond doubt by the occurrence of the effect on the 0–0 sub-band which exhibits the isotopic head in a wavelength direction opposite to the expected one.     

Vibrational spectra dihalogenated benzenes. I. In-plane vibrations

Infrared and Raman spectra of D₄-ortho, meta and para fluorochloro and fluorobromo benzenes are presented and assignments are given. Some of the bands of H₄-p-fluorochloro benzene assigned earlier as fundamentals are shown to be due to impurities and alternate assignments are given. The observed frequencies of the H₄ and D₄ molecules are combined in a normal coordinate analysis to obtain a 33-parameter modified valence force field, for the in-plane vibrations, with an average difference of ±0.8% between observed and calculated frequencies. The normal coordinate analysis shows that many of the previous assignments of the ring modes ν₁, ν₆, and ν₁₂ for disubstituted benzenes are not very reliablie. Revised assignments with good correlation with the corresponding benzene modes are given.     

Cosmic ray muons at a depth of 754 hg/cm2 in the Kolar gold Mines

A telescope of area 4 m², consisting of horizontal layers of plastic scintillators, neon flash tubes and absorbers was operated at a depth of 754 hg/cm² in the Kolar Gold Mines. New values for the vertical intensities of muons have been obtained from observations of the angular distribution over the slant depths ∼ 750–2300 hg/cm² and are compared with the existing measurements. From the angular distribution observed, we conclude that muons are produced wholly through the decay of pions and kaons up to energies of the order of 1 TeV. A value of 0.3±0.2 is estimated for theK/π ratio at production, for muon energies around 500 GeV. A decoherence distribution has been obtained for parallel muon events up to distances of the order of 10 m. From this we conclude that the averageP _t of the parents of muons of energy ∼ 250 GeV is of the order of 0.3 GeV/c. From an analysis of rock showers, we obtain the cross section for inelastic interaction of muons of mean energy 100 GeV as (3.8±1.5)×10⁻³⁰ cm²/nucleon.     

On the asymptotic normality and independence of the sample partial autocorrelations for an autoregressive process

For a stationary autoregressive model of order s, the partial autocorrelation coefficients of order $\text{j}$, $\text{j}$=0,1,2,…,s?1, are defined; the partial autocorrelation coefficient of order zero being the same as the autocorrelation coefficient of order one. Denoting these s parameters by ?₁,π₁,…,π_s?1, it is shown that their sample images, namely r₁,$\text{P}$₁,…,$\text{P}$_s?1, are asymptotically independently normally distributed with means equal to the corresponding population values and asymptotic variances given by

$\text{var(r}{}_1\text{)=}\text{(1 ? ?}\text{2}\text{1}\text{)(1 ? π}\text{2}\text{1}\text{?(1 ? π}\text{2}\text{s ?1}\text{)}\text{n}\text{,}$

$\text{var(}\text{P}{}_{\mathrm{<mtext>j</mtext>}}\text{)=}\text{(1 ? π}\text{2}\text{j}\text{(1 ? π}\text{2}\text{j}\text{+1}\text{)?(1 ? π}\text{2}\text{s ?1}\text{)}\text{n}$

,

$\text{j}\text{=1,2,…,s?1,}$

where n is the size of the sample from the autoregressive process of order s. The partial correlogram of the model and application of the result are discussed.     

Electrical properties of GeSbSe glasses

The dc and ac conductivities of glasses of the system GeSbSe (with the general formula Ge_xSb₁₀Se_90?x have been studied. The dc conductivity results indicate a maximum in the glass transition temperature and activation energy and a minimum in conductivity for the composition Ge₂₅Sb₁₀Se₆₅. These results have been explained on the basis of the prevalent structural arrangement wherein structural units of GeSe₂ and Sb₂Se₃ are dispersed among excess Se or Ge. Based on this picture, a model has been developed which accounts for the observed dependence of conductivity on composition at any temperature. The ac results have been utilized to find the hopping conductivity as a function of composition; the characteristics of lone pair amorphous semiconductors seem to account for the observed features.     

Intensity measurement of laser-excited fluorescence in the B3Πu(0+)-X1Σg+ system of diatomic lodine

Fluorescence was excited in the B³Π_u(0⁺)-X¹Σ_g⁺ system of diatomic iodine by means of the 5145-Å line of an Ar⁺ laser and the 6328-Å line of a HeNe laser. The resulting spectrum was recorded on a SPEX double monochromator and a quantitative measurement of the intensities was carried out. The variation of the electronic transition moment $\text{M(}\text{R}\text{)}$ with R centroid observed by us shows a behavior similar to what has been reported earlier.     

Rotational analysis of the 0–9, 0–10 and 0–11 bands of theA 2II u -X 2II g band system of (16O18O)+

High-resolution spectra of the 0–9, 0–10 and 0–11 bands of theA ²II _u —X ²II _g system of (¹⁶O¹⁸O)⁺ ion have been studied for their rotational structure. This study enables a direct determination of the Λ-doubling parameters of theA ²II _u andX ²II _g states. The model of ‘pure precession’ explains, though not entirely, the Λ-doubling of theX ²II _a state as arising out of its interaction with theB ² Σ _g ⁻ state. The Λ-doubling in theA ²II _u state was found insignificant.