Effect of high doses of N<Superscript>+</Superscript>, N<Superscript>+</Superscript> + Ni<Superscript>+</Superscript>, and Mo<Superscript>+</Superscript> + W<Superscript>+</Superscript> ions on the physicomechanical properties of TiNi

The surface layer of an equiatomic TiNi alloy, which exhibits the shape memory effect in the martensitic state, is modified with high-dose implantation of 65-keV N⁺ ions (the implantation dose is varied from 10¹⁷ to 10¹⁸ ions/cm²). TiNi samples are implanted by N⁺, Ni⁺-N⁺, and Mo⁺-W⁺ ions at a dose of 10¹⁷–10¹⁸ cm⁻² and studied by Rutherford backscattering, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction (glancing geometry), and by measuring the nanohardness and the elastic modulus. A Ni⁺ concentration peak is detected between two maxima in the depth profile of the N⁺ ion concentration. X-ray diffraction (glancing geometry) of TiNi samples implanted by Ni⁺ and N⁺ ions shows the formation of the TiNi (B2), TiN, and Ni₃N phases. In the initial state, the elastic modulus of the samples is E = 56 GPa at a hardness of H = 2.13 ± 0.30 GPa (at a depth of 150 nm). After double implantation by Ni⁺-N⁺ and W⁺-Mo⁺ ions, the hardness of the TiNi samples is ∼2.78 ± 0.95 GPa at a depth of 150 nm and 4.95 ± 2.25 GPa at a depth of 50 nm; the elastic modulus is 59 GPa. Annealing of the samples at 550°C leads to an increase in the hardness to 4.44 ± 1.45 GPa and a sharp increase in the elastic modulus to 236 ± 39 GPa. A correlation between the elemental composition, microstructure, shape memory effect, and mechanical properties of the near-surface layer in TiNi is found.     

Contributions from SUSY-FCNC couplings to the interpretation of the HyperCP events for the decay Σ<Superscript>+</Superscript>→pμ<Superscript>+</Superscript>μ<Superscript>-</Superscript>

The observation of three events for the decay Σ⁺→pμ⁺μ^- with a dimuon invariant mass of 214.3 ± 0.5 MeV by the HyperCP Collaboration implies that a new particle X may be needed to explain the observed dimuon invariant mass distribution. We show that there are regions in the SUSY-FCNC parameter space where the A⁰ ₁ in the NMSSM can be used to explain the HyperCP events without contradicting all the existing constraints from the measurements of the kaon decays, and the constraints from K⁰–K̄⁰ mixing are automatically satisfied once the constraints from kaon decays are satisfied. PACS  14.80.Cp; 12.60.Jv; 14.20.Jn     

Graviton resonances in e<Superscript>+</Superscript>e<Superscript>-</Superscript>→μ<Superscript>+</Superscript>μ<Superscript>-</Superscript> at linear colliders with beamstrahlung and ISR effects

The electromagnetic radiation emitted by colliding beams is expected to play an important role at the next generation of high energy e⁺e^- linear colliders. Focussing on the simplest process, e⁺e^-→μ⁺μ^-, we show that, for suitable machine parameters and luminosity, radiative effects like initial state radiation (ISR) and beamstrahlung can be used to search for resonant graviton modes of the Randall–Sundrum model in an efficient manner.     

Emission of Ionic Molecules (KrXe)<Superscript>+</Superscript> on Excitation by a Hard Ionizer

The molecular luminescence band appearing in the 445–510-nm region on excitation of a Kr-Xe mixture by the α particles of polonium 210 as well as by the products of nuclear reaction ³He(n,p)T has been investigated. Radiation at the transition of the heteronuclear ionic molecule (KrXe)⁺ has a high excitation efficiency and is observed in a temperature range from −100 to +600°C. The kinetics of the processes in the Kr-Xe mixture and the possibility of using radiation with λ ∼ 490 nm in radioactive light sources are considered. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 301–304, May–June, 2005.     

Electron impact dissociation of ND<Superscript>+</Superscript>: formation of D<Superscript>+</Superscript>

Absolute cross sections for electron impact dissociation of ND⁺ leading to the formation of D⁺ have been measured by applying the animated electron-ion beam method in the energy range from the reaction threshold up to 2.5 keV. The maximum inclusive cross section is observed to be (16.8 ± 0.8) × 10⁻¹⁷ cm² at the electron energy of 65.1 eV. The appearance energy for the D⁺ production is measured to be (4.0 ± 0.5) eV. Collected data are analyzed in details by means of an original procedure in order to determine separately the contributions of dissociative channels. A specific Monte Carlo modeling has been developed, which is proven to reconstruct adequately the dissociative ionization cross section. The present energy thresholds provide information about the ground and excited states of the molecular ion, as well as about the possible population of the vibrational levels. The reaction D₂(v) + N⁺ (or H₂(v) + N⁺) is a probable source for that population and it constitutes the first step of the molecular activated processes, so the corresponding chain of reactions has to be considered to study the chemistry of plasma sources.     

Kinetics of Rb<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and Rb<Superscript>+</Superscript> formation in laser-excited rubidium vapor

We have studied the formation of the molecular ion Rb₂⁺ and the atomic ion Rb⁺. These are created in laser excited rubidium vapor at the first resonance, 5s–5p and 5p-nl transitions. A theoretical model is applied to this interaction to explain the time evolution and the laser-power dependence of the population density of Rb⁺ and Rb₂⁺. A set of rate equations which describe: the temporal variation of the population density of the excited states; the atomic ion density; and the electron density, were solved numerically under the experimental conditions of Barbier and Cheret. In their experiment the Rb concentration was 1×10¹³cm⁻³ and the laser power was taken to be 50–500 mW at vapor temperature = 450 K. The results showed that the main processes for producing Rb₂⁺ are associative ionization and Hornbeck-Molnar ionization. The calculations have also showed that, the atomic ions Rb⁺ are formed through the Penning Ionization (PI) and photoionization processes. Moreover, a reasonable agreement between the experimental results and our calculations for the ion currents of the Rb⁺ and Rb₂⁺ is obtained.      

A cobalt-doped transparent glass ceramic saturable absorber Q-switch for a LD pumped Yb<Superscript>3+</Superscript>/Er<Superscript>3+</Superscript> glass microchip laser

We fabricate a transparent glass ceramic contains magnesium-aluminum spinel nanocrystallites doped with Co²⁺ ions. The ground-state and excited-state absorption cross section of this glass ceramic at 1.54 μm are estimated to be (2.8 ± 0.3) × 10⁻¹⁹ cm² and (4.8 ± 0.5) × 10⁻²⁰ cm², respectively. For the first time, the passively Q-swithched operation of LD pumped 1.54 μm microchip Yb³⁺/Er³⁺ glass laser is realized with transparent glass ceramic as saturable absorber. The Q-switched pulses of 3.846 kHz in repetition rate, 6.2 ns in duration and 6.3 μJ in energy are obtained. At last, the dependences of pulse width and repetition rate on pump power are also investigated.     

Validated Spectrofluorimetric Method for the Determination of Lamotrigine in Tablets and Human Plasma Through Derivatization with <Emphasis Type="BoldItalic">o</Emphasis>-phthalaldehyde

A sensitive, simple and selective spectrofluorimetric method was developed for the determination of Lamotrigine (LMT) in pharmaceutical formulations and biological fluids. The method is based on reaction of LMT with o-phthalaldehyde in presence of 2-mercaptoethanol in borate buffer of pH 9.8 to yield a highly fluorescent derivative that is measured at 448 nm after excitation at 337 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence-concentration plot was rectilinear over the range of 0.1–1.0 μg ml⁻¹ with lower limit of detection (LOD) 0.02 μg ml⁻¹ and limit of quantification (LOQ) 0.06 μg ml⁻¹ respectively. The proposed method was successfully applied to the the analysis of commercial tablets. Statistical comparison of the results obtained by the proposed and reference method revealed no significant difference in the performance of the two methods regarding the accuracy and precision respectively. The proposed method was further extended to the in-vitro and in-vivo determination of the drug in spiked and real human plasma. The mean percentage recoveries in spiked and real human plasma (n = 3) were 95.78 ± 1.37 and 90.93 ± 2.34 respectively. Interference arising from co-administered drugs was also studied. A proposal for the reaction pathway with o-phthalaldehyde was postulated.     

Spectrofluorimetric Assessment of Doxycycline Hydrochloride in Pharmaceutical Tablets and Serum Sample Based on the Enhancement of the Luminescence Intensity of the Optical Sensor Sm<Superscript>3+</Superscript> Ion

A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably enhance the luminescence intensity of the Sm³⁺ ion in Sm³⁺- DC complex at λ_ex = 400 nm. The produced luminescence intensity of Sm³⁺- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic range for the determination of DC is 1 × 10⁻⁸ – 5 × 10⁻⁶ mol L⁻¹ and in case of quantum yield calculations is 7 × 10⁻⁹ – 5 × 10⁻⁶ mol L⁻¹ with detection limit of 6.5 × 10⁻¹⁰ mol L⁻¹. The enhancement mechanism of the luminescence intensity in the Sm³⁺- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which Eu³⁺ ion is used instead of Sm³⁺ ion is also studied.     

The pp→K<Superscript>+</Superscript><Emphasis Type="Italic">Σ</Emphasis><Superscript>+</Superscript>n cross-section from missing-mass spectra

We utilize existing inclusive data on K⁺-meson momentum spectra of the reaction pp→K ⁺ X at T _p = 2.3-2.85GeV to deduce total cross-sections for pp→K ⁺ Σ ⁺ n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T _p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained for T _p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration at a somewhat lower beam energy, indicating that the pp→K ⁺ Σ ⁺ n reaction cross-section could exhibit a rather unusual energy dependence.     

Reductive hydrothermal synthesis of La(OH)<Subscript>3</Subscript>:Tb<Superscript>3+</Superscript> nanorods as a new green emitting phosphor

A reductive hydrothermal process with use of hydrazine hydrate as a protecting agent is proposed to synthesize La(OH)₃:Tb³⁺ (Tb mol% = 0, 1, 5, 10, and 20) nanorods. The oxidation of Tb³⁺−Tb⁴⁺ was effectively prevented in the presence of hydrazine hydrate; hence the La(OH)₃:Tb³⁺ nanorods exhibited much stronger green photoluminescence than the product prepared by the normal hydrothermal process. X-ray diffraction and transmission electron microscopy were employed to characterize the products, the results of which revealed that all the products were one-dimensional rod-like nanostructures of hexagonal structure (∼20 nm in diameter). The reductive hydrothermal process is desirable for the synthesis of other efficient Tb³⁺ doped nanophosphers.     

New fluorimetric reagents, sodium pyrophosphate, sodium trimetaphosphate, and sodium tetrametaphosphate, for the determination of cerium(III)

Three sensitive and selective new alternatives for fluorometric determination of cerium(III) are described in this study. Ce(III) is highly fluorescent in sodium pyrophosphate, sodium trimetaphosphate, and sodium tetrametaphosphate solutions. For these reagents, the maximum excitation/emission wavelengths are 300/350, 297/340, and 299/352 nm, respectively. Maximum fluorescence intensities are obtained by irradiating Ce(III) dissolved in 0.033 g L⁻¹ sodium pyrophosphate, 41.4 g L⁻¹ sodium trimetaphosphate, and 0.96 g L⁻¹ sodium tetrametaphosphate at room temperature. The fluorescence intensities are linear over the range 0.001–30, 0.001–75, and 0.001–70 μg ml⁻¹. The detection limits are calculated as 9.5 × 10⁻³, 1.1/10⁻³, and 3.8 × 10^-3 μg ml⁻¹ Ce(III), respectively. The relative standard deviations for 15/0.05 Μg ml⁻¹ Ce(III) are 1.1/1.2, 1/1.1, and 1.2/1.3%, respectively. Quenching effects of other lanthanides and some inorganic anions were investigated. The methods have been applied to rare earth mixtures with a good accuracy.     

Simultaneous Determination of Acetylsalicylic Acid and Caffeine in Pharmaceutical Formulation by First Derivative Synchronous Fluorimetric Method

A sensitive, rapid, and specific assay has been developed for the simultaneous determination of acetylsalicylic acid and caffeine in commercial tablets based on their natural fluorescence. The mixture of these drugs was resolved by first derivative synchronous fluorimetric technique using two scans. At Δλ=106 nm, using first derivative synchronous scanning, only acetylsalicylic acid yields a detectable signal at 316 nm (peak to zero method) which is unaffected by caffeine. At Δλ=30 nm, the signal of caffeine at 288 nm (peak to zero method) is not affected by acetylsalicylic acid. The range of application is between 0.021 and 41.62 μg ml⁻¹ (correlation coefficient, R=0.9995) for acetylsalicylic acid and between 0.4486 and 44.86 μg ml⁻¹ (correlation coefficient, R=0.99786) for caffeine. The recovery range of 98.40–102% for acetylsalicylic acid and 90–100.5% for caffeine from their synthetic mixture was reported. Overall recovery of both compounds about 97–99% for acetylsalicylic acid and 97–98% for caffeine was obtained from real sample analysis. The detection limits are 0.0013 μg ml⁻¹ and 0.0306 μg ml⁻¹ for acetylsalicylic acid and caffeine, respectively. The relative standard deviation (n=10) for 20 μg ml⁻¹ of acetylsalicylic acid is 2.75% and for 2.2 μg ml⁻¹of caffeine is 1.7%.     

Spectroscopic properties of Nd<Superscript>3+</Superscript>:CaNb<Subscript>2</Subscript>O<Subscript>6</Subscript> crystal

The absorption spectra, fluorescence spectrum and fluorescence decay curve of Nd³⁺ ions in CaNb₂O₆ crystal were measured at room temperature. The peak absorption cross section was calculated to be 6.202×10⁻²⁰ cm² with a broad FWHM of 7 nm at 808 nm for E//a light polarization. The spectroscopic parameters of Nd³⁺ ions in CaNb₂O₆ crystal have been investigated based on Judd-Ofelt theory. The parameters of the line strengths Ω _t are Ω ₂=5.321×10⁻²⁰ cm²,Ω ₄=1.734×10⁻²⁰ cm²,Ω ₆=2.889×10⁻²⁰ cm². The radiative lifetime, the fluorescence lifetime and the quantum efficiency are 167 μs, 152 μs and 91%, respectively. The fluorescence branch ratios are calculated to be β ₁=36.03%,β ₂=52.29%,β ₃=11.15%,β ₄=0.533%. The emission cross section at 1062 nm is 9.87×10⁻²⁰ cm².     

Kinetics of radiation-induced segregation in 12Cr-MoWSiVNbB steel after Ni<Superscript>++</Superscript> and He<Superscript>+</Superscript> ion irradiation

Ferritic-martensitic 12Cr-MoWSiVNbB (EP-823) steel was irradiated with 7 MeV Ni⁺⁺ ions within fluence interval 5 × 10¹⁸−5.4 × 10¹⁹ ions/m² and with 30 and 70 keV He⁺ ions within fluence interval 10²⁰–10²¹ ions/m² at 500°C. Results from a comparative analysis of Cr and Si radiation-induced segregation profiles near the surface are presented. Dependence of the amount of surface segregation on damage dose, displacement generation rate, and radiation-induced point defects concentration is established.     

Defect Structure and Up-conversion Luminescence Properties of ZrO<Subscript>2</Subscript>:Yb<Superscript>3+</Superscript>,Er<Superscript>3+</Superscript> Nanomaterials

The up-converting ZrO₂:Yb³⁺,Er³⁺ nanomaterials were prepared with the combustion and sol–gel methods. FT-IR spectroscopy was used for analyzing the impurities. The crystal structures were characterized with X-ray powder diffraction and the mean crystallite sizes were estimated with the Scherrer formula. Up-conversion luminescence measurements were made at room temperature with IR-laser excitation at 977 nm. The IR spectra revealed the conventional and OH⁻ impurities for the combustion synthesis products. The structure of the ZrO₂:Yb³⁺, Er³⁺ nanomaterials was cubic except for the minor monoclinic and tetragonal impurities obtained with the sol–gel method. The materials showed red (650–700 nm) and green (520–560 nm) up-conversion luminescence due to the ⁴F_9/2→⁴I_15/2 and (²H_11/2, ⁴S_3/2)→⁴I_15/2 transitions of Er³⁺, respectively. The products obtained with the combustion synthesis exhibited the most intense luminescence intensity and showed considerable afterglow.     

Longitudinal dynamics of <Superscript>197</Superscript>Au<Superscript>32+</Superscript> and <Superscript>197</Superscript>Au<Superscript>79+</Superscript> ions in NICA injection chain

The main objective of the NICA project developed at the Joint Institute for Nuclear Research (JINR) is to conduct experimental studies with colliding heavy ion beams in an energy range of 1–4.5 GeV/nucleonucleon with luminosity on the level of 1 × 10²⁷ cm⁻² s⁻¹. In this paper the operation regime of the collider injection chain providing the bunch with experimentally desirable parameters at the output of the Nuclotron is considered for gold ions as an example.     

Lepton polarization asymmetry and forward–backward asymmetry in exclusive B→K<Subscript>1</Subscript>τ<Superscript>+</Superscript>τ<Superscript>-</Superscript> decay in universal extra dimension scenario

Decay rate, forward–backward asymmetry and polarization asymmetries of the final state leptons in B→K₁τ⁺τ^-, where K₁ is the axial vector meson, are calculated in the standard model and in the universal extra dimension (UED) model. The sensitivity of the observables to the compactification radius R, the only unknown parameter in the UED model, is studied. Finally, the helicity fractions of the final state K₁ are calculated and their dependence on the compactification radius is discussed. This analysis of the helicity fraction is briefly extended to B→K^*ℓ⁺ℓ^- (ℓ=e,μ) and compared with the other approaches existing in the literature.     

Blackbody radiation shift of the Al<Superscript>+</Superscript> clock transition

The blackbody radiation shift of the Al⁺ 3s^{2 1}S^e ₀ ↦ 3s3p ³P^○ ₀ clock transition is evaluated. The polarizabilities of the two states are determined by means of configuration interaction calculations in conjunction with oscillator strength sum rules. The ground state polarizability was 24.14 ±0.12 a.u. while the metastable state polarizability was 24.62 ±0.25 a.u. The derived frequency shift at 300 K was Δν= -0.0042 ±0.0032 Hz. Some auxiliary sum rules are evaluated that allow for the conversion of a finite frequency polarizability difference to a static polarizability difference.     

Effect of isoelectronic impurities K<Superscript>+</Superscript> and I<Superscript>−</Superscript> on luminescence of CsBr:Eu<Superscript>2+</Superscript> crystals

We have investigated the photoluminescence (PL) and photostimulated luminescence (PSL) spectra at 300 K to study the effect of isoelectronic impurities K⁺ and I⁻ on the formation and energy structure of Eu²⁺-V_Cs isolated dipole centers and aggregate centers in the form of single crystals of CsEuBr₃ in CsBr:Eu²⁺ single crystals. We have shown that K⁺ and I⁻ impurities in a concentration of 5 mol% do not have a substantial effect on the energy spectrum of isolated dipole centers in CsBr:Eu²⁺ single crystals and the processes for the formation of such centers during growth of CsBr:Eu single crystals from the melt by the Bridgman method. We have established that in Cs_0.95K^0.05Br:Eu²⁺, more favorable conditions are realized for the formation of aggregate centers than in CsBr:Eu²⁺ and CsBr^0.95K^0.05Br:Eu²⁺ single crystals. So in order to improve the storage properties of phosphors based on CsBr:Eu²⁺, in particular for increasing the efficiency of PSL excitation, it is expedient to dope them with K⁺ impurity in a concentration up to 5 mol%. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 627–630, September–October, 2007.