L X-ray energy shifts and intensity ratios in tantalum with C and N ions — multiple vacancies in M, N and O shells

The energy shifts and intensity ratios of different L X-ray components in tantalum element due to 10 MeV carbon and 12 MeV nitrogen ions are estimated. From the observed energy shifts, the possible number of simultaneous vacancies in M shell are estimated. A comparison of L _α /L _β2.15, L _β1/L _γ1 and L _γ2.3/L _γ4.4 with the ratios due to Scofield theoretical transition rates indicate that the number of multiple vacancies in N shell are higher than the vacancies in M and O shell. Employing Larkin’s statistical scaling procedure, the number of possible multiple vacancies in N and O shells are estimated quantitatively.     

Paramagnetic resonance studies of Cu2+ doped in NH4Br

Electron Paramagnetic Resonance studies of Cu²⁺ doped in NH₄Br single crystals have been carried out for the first time. The room temperature data reveal that Cu²⁺ ions go predominantly to interstitial sites having square planar co-ordination of four Br^? ions. For this type of complexes the bromine: superhyperfine structure: is observed on the normal hyperfine structure lines of copper. Existence of other weak spectra indicates that a relatively few Cu⁺⁺ ions go substitutionally to (NH₄)⁺ ions, and are probably associated with a first or a second nearest neighbour cation vacancy, among the two, the latter being more predominant. However, the low temperature studies corresponding to the tetragonal phase of NH₄Br indicate that a number of Cu²⁺ ions at interstitial sites get readjusted to the lattice sites after phase transformation. The spectra in both the phases are analysed by the usual spin Hamiltonian method.     

Mean amplitudes of vibration: Bent XYZ molecules

The theory of mean-square amplitude matrices is applied to the bent XYZ molecules. The principal mean amplitudes of vibration for the molecules investigated here are reported for 300° K.     

Chemical examination of Embelia ribes—V Synthesis of some N-bis(anhydrobenzoquinones)

By the condensation of embelin (I) with various nitroso compounds, the corresponding N-bis-anhydrobenzoquinones (II) have been synthesized and their properties recorded.     

Efficient Regio‐ and Stereoselective Conversions of Oxiranes and Aziridines into β‐(Nitrooxy)‐Substituted Alcohols and Amines by Using Bismuth Nitrate

Oxiranes and aziridines efficiently undergo ring opening with bismuth nitrate at room temperature to furnish the corresponding β‐(nitrooxy)‐substituted alcohols and amines respectively. The conversions are highly regio‐ and stereoselective and afford the nitrooxy‐compounds in excellent yields within a short period of time.     

Competitive cascade cyclization of 2′-tosyloxychalcones: An easy access to thioflavones and thioaurones

Abstract

A new and efficient approach for the synthesis of thioflavones and thioaurones by competitive cascade cyclization of 2′-tosyloxychalcones has been developed. 2′-Tosyloxychalcones were smoothly converted into thioflavones and thioaurones by incorporation of sulfur atom using elemental sulfur and triethylamine in DMSO with good yields. The advantages of the methodology are the formation of both thioflavones and thioaurones in a single step. Easily accessible substrates, mild reaction conditions and compatibility with a broad range of functional groups make this protocol clean and inexpensive.     

Periodic multisequences with large error linear complexity

Generalizing the theory of k-error linear complexity for single sequences over a finite field, Meidl et al. (J. Complexity 23(2), 169–192 (2007)) introduced three possibilities of defining error linear complexity measures for multisequences. A good keystream sequence must possess a large linear complexity and a large k-error linear complexity simultaneously for suitable values of k. In this direction several results on the existence, and lower bounds on the number, of single sequences with large k-error linear complexity were proved in Meidl and Niederreiter (Appl. Algebra Eng. Commun. Comput. 14(4), 273–286 (2003)), Niederreiter (IEEE Trans. Inform. Theory 49(2), 501–505 (2003)) and Niederreiter and Shparlinski (In: Paterson (ed.) 9th IMA International Conference on Cryptography and Coding (2003)). In this paper we discuss analogous results for the case of multisequences. We also present improved bounds on the error linear complexity and on the number of sequences satisfying such bounds for the case of single sequences.     

Laser photoacoustic spectroscopy of iodine molecule: Single and two-photon absorption

Photoacoustic spectroscopy of iodine molecule has been studied in gas phase using nitrogen laser-pumped tunable dye laser. The experiment yielded the vibrational spectrum corresponding toX ¹Σ⁺(0 _g ⁺ )→B ³Π(0 _g ⁺ ) transition up to the convergence limit. The photo-acoustic spectrum in the region 17580–18850 cm⁻¹ is presented along with the vibrational analysis. Five of the vibrational bands reported earlier by Venkateswarlu, Kumar and McGlynn have been partially resolved and the structure of one of them has been analyzed and shown to be due to an overlap of (14, 2) and (12, 1) bands. The analysis was based on a comparison with the highly resolved spectrum of Gerstenkorn and Luc. The structure observed in the region 20200–20750 cm⁻¹ which is beyond the convergence limit of the transitionX ¹Σ⁺(0 _g ⁺ )→B ³Π(0 _u ⁺ ) has been analyzed as due to two-photon absorption. Most of the bands could be assigned to two transitions both originating in the ground state and terminating in two different electronic states 1 _g andE(0 _g ⁺ ), atT _e=40821 cm⁻¹ (orT ₀=41355 cm⁻¹) andT _e=41411 cm⁻¹ (orT ₀=41355 cm⁻¹) respectively.