Der Zerfall des 1,5 min-Isomers Co54m

Co^54m (T _1/2=1.43 min) was produced in iron-foils by irradiation with_dE=19 MeV deuterons. The gamma ray spectrum was investigated using a NaJ(Tl) scintillation spectrometer, a coincidence circuit and a Ge(Li)-counter. There were observed three gamma rays having the following energies and intensities per Co_54m decay: 411 keV (0.97±0.07), 1130keV (0.98±0.05), 1407 keV (1.00±0.05). The directional correlation between the pairs of gamma rays were determined. These results correspond to spin and parityJ _π=2⁺ for the 1407 keV,J _π=4⁺ for the 2537 keV, andJ _π=6⁺ for the 2948 keV energy level of Fe⁵⁴. The last-mentioned level was not excited in previous scattering experiments. Our results are compatible withE=210keV andJ _π=6⁺ or 7⁺ of the isomeric state of Co^54m .     

钴离子注入对二氧化钛晶体的结构和光学性能的影响

采用离子注入法制备了钴离子掺杂的金红石相TiO₂样品;离子注入能量、注量分别为40 keV(1×10¹⁶cm^-2),80 keV(5×10¹⁵,1×10¹⁶,5×10¹⁶,1×10¹⁷cm^-2),120 keV(1×10¹⁶cm^-2). 通过XRD,XPS和UV-Vis等手段对掺杂前后样品的结构和光学性能进行了表征,分析了掺杂元素在金红石TiO₂中的存在形式. XRD测试表明随着注入能量的增加晶体的损伤程度增加. UV-Vis测试表明掺杂后所有样品在可见光区的吸收增强; 并且随着注量的增加,注量为5×10¹⁵cm^-2到5×10¹⁶cm^-2范围内注入样品的光学带隙逐渐变小. 关键词： 钴 二氧化钛 离子注入 掺杂     

Zn-Co oxide electrodes with excellent capacitive behavior for using supercapacitor application

In the present study, super-capacitive behavior of spinel Zn-Co oxides (with different Zn⁺²/Co⁺² mol ratio) has been thoroughly investigated. The spinel of transition metal oxides with different morphologies has been synthesized with hydrothermal method on Ni foam as substrate layer. The specific capacitance of the Zn-Co oxide electrode prepared at 180 °C for 5 h with different Zn⁺²/Co⁺² mol ratios of 1:0, 2:1, 1:1, 1:2, 0:1 were investigated and measured 405, 842, 726, 1237, 705 F g^?1, respectively at 50 mV s^?1 scan rate. Zn-Co oxide with Zn⁺²/Co⁺² mol ratio of 1:2 was also synthesized at two different temperatures of 120 and 150 °C for 5 h with the specific capacitance of 1147, 917 F g^?1 at 50 mV s^?1 scan rate, respectively. Among the obtained data, the sample with Zn⁺²/Co⁺² mol ratio of 1:2 prepared at 180 °C for 5 h possessed highest specific capacitance. The cyclic life of this electrode showed 92% capacitance retention after 1000 cycle of charge-discharge. All results revealed that Zn-Co oxides had excellent supercapacitive properties due to multiple oxidation states and fast ion/electron transfer at the surface of electrode which could be offered as suitable devices for energy storage applications.     

Der Zerfall Co58m →Co58g

Co^58m , Co^58g and Co⁵⁵ were obtained by radiating nickel-foiles with deuterons of energies 11,5 MeV and 2,07 MeV. The γ-radiation was measured with NaJ scintillation spectrometers. For the isomeric transition of Co^58m was determinedT _1/2=(9.15±0.1)h,T _γ=(25±1)keV,α _K=2200±300 and α_L+M=1100±300. From these values it follows, that the radiation is ofM3-type. Twoγ-energies of 95 keV and 1322 keV were found belonging to Co⁵⁵.     

Radiation damage and annealing studies of ion bombarded cobalt

The effects of implantation-induced radiation damage on the thermal oxidation of cobalt have been studied. Bombardment by both Co⁺ self-ions and by Xe⁺ has been studied as a function of ion dose, energy and annealing temperature. A major increase in oxidation was observed for doses of >10¹⁶ Co⁺ cm^–2 in agreement with previous studies on Al. The oxidation behaviour as a function of annealing temperature was markedly different for Co⁺ and Xe⁺ bombarded samples. For Co⁺ bombarded samples, damage anneals rapidly in the temperature range 20–300°C due to thermally assisted repair of point defects and vacancy clusters. However, for Xe⁺ bombardment, it is proposed that the higher annealing temperatures required for damage repair arise due to the stabilisation of three-dimensional vacancy clusters by the oversized Xe atoms. The increase in oxidation after annealing in the temperature range 300–500°C is thought to be due to vacancy release mechanisms which may affect oxide nucleation.     

Mössbauer and infrared spectroscopic studies of novel mixed valence states in cobaltous ferrocyanides and ferricyanides

Novel mixed valence states have been obtained by the treatment of cobaltous ferrocyanides (Co⁺²Fe^II) and ferricyanides (Co⁺²Fe^III) in an ozone flow. The CN stretching bands occur at 2085 cm^–1 for Co⁺²Fe^II and at 2160 cm^–1 for Co⁺²Fe^III. After the ozonization process of Co⁺²Fe^II, an intense band approximately at 2125 cm^–1 is detected. This intermediate band must correspond to a mixed valence state of the type: Fe^II–CN–Co²⁺–NC–Fe^III Mössbauer spectra recorded in situ during the ozonization of Co⁺²Fe^II show the presence of two components: a doublet with isomer shift and quadrupole splitting values close to the cobalti ferricyanide and a very broad line for the mixed valence state. From the Mössbauer and infrared spectra of the aged samples of the Co⁺²Fe^II after ozonization, a relaxation process to the initial state of the samples is observed but the mixed valence state is stable.     

Enhancing up conversion luminescence effect of β-NaYF<Subscript>4</Subscript>: Yb<Superscript>3+</Superscript> and Tm<Superscript>3+</Superscript> by Li<Superscript>+</Superscript> ion doped approach

Up-conversion (UC) is a photoluminescence process which converts few low energy photons to a higher energy photon. This process has more potential usages in many different fields like bioimaging, solar spectrum tuning, and security encoding. Nowadays, researches about UC mostly focusing on biomedical signory and synthesis of nanoparticles. The synthesis of NaYF₄ nanoparticles executed under series of pH value condition results in different morphology and photoluminescence effect. Samples in low pH value created better consequent and quality than the specimen which had higher pH value. In addition, we observed NaYF₄ samples of doping Li⁺, realizing that the action of distorting in the local symmetry around rare-earth ions is caused by Li⁺ doping. The NaYF₄ microparticles which doped higher concentration of Li⁺ has strong fluorescence properties and intensities compared with their corresponding group of Li⁺-free, the blue emission 479 nm luminescence intensities and 454 nm luminescence intensities in NaYF₄:Yb³⁺, Tm³⁺ microparticles doped 20 mol% Li⁺ are enhanced 3 and 8 times, separately. And violet emission luminescence intensities around 345 and 360 nm are about 10 and 7 times, respectively. The result indicated that the improved UC luminescence of NaYF₄:Yb³⁺. Tm³⁺ microparticles with Li⁺ doping have potentially applications.     

Dopant dependent stability of Co n TM+ (TM = Ti,V, Cr,and Mn) clusters

In this paper, we present a photofragmentation study of mass-selected transition metal-doped cobalt cluster cations Co _n TM⁺  (n = 8–18, TM = Ti, V, Cr, and Mn). Time-of-flight spectra recorded after laser excitation of mass-selected clusters in the gas phase show that the evaporation of a cobalt atom is the most facile dissociation channel for clusters with TM = Ti and V, suggesting an enhanced stability of the doped clusters compared to the bare ones. In contrast, for Co _n TM⁺ with TM = Cr and Mn, the loss of the dopant atom is found to be the preferred dissociation channel. Co₁₃Cr⁺ is a notable exception and favors dissociation by loss of a neutral Co atom. It is implied that substituting Mn and Cr generally destabilizes the cobalt clusters with the exception of Co₁₂Cr⁺, which is relatively more stable than Co ₁₃ ⁺ . Additional measurements of V _n Co⁺ (n = 9–16) show that the loss of a Co atom is still the most facile dissociation channel, which is in agreement with the predicted stronger V?V bond compared to the V?Co one.     

Hydrogen on W(100): temperature dependence of LEED and angle-resolved ESD

For hydrogen adsorption on W(100), the evolution of the c(2 × 2) LEED intensities and of the H⁺ ESD signal with H coverage have been investigated for various adsorption and annealing temperatures. Striking changes have been found for the half-order LEED intensities in the temperature range 140–360 K, in agreement with other workers, where the H⁺ signal showed only minor differences. The maxima of the LEED and the ESD intensities, however, occurred at the same exposure throughout this range (≈25% of saturation coverage). A temperature dependent variation of the height of the H⁺ maximum was observed which was reversible up to the desorption temperature of the β₂ hydrogen phase. The H⁺ ESDIAD lobe was found to have a polar FWHM of about 21°, independent of temperature between 140 and 450 K, and without any azimuthal dependence. These results provide evidence for the assumption that the observable H⁺ ions desorb from reconstructed sites. The number of these sites depends on temperature and hydrogen coverage, as shown by the change of the H⁺ current with these parameters. The transition from H on reconstructed to H on unreconstructed sites is of the order-order type; the energy difference between the two different adsorbate situations is about 135 meV/site at the quarter coverage. The consistency of the results and conclusions with a bridge-site model for H adsorption is shown. Elastic interactions lead to agglomeration of adsorbed H. The azimuthal isotropy of the ESDIAD lobes is interpreted by a superposition of emission from various types of bridge-sites which smear out the anisotropy expected for individual bridge-sites.     

Ion beam shaping of embedded metal nanoparticles by Si+ ion irradiation

Fine Co and Pt nanoparticles are nucleated when a silica sample is implanted with 400 keV Co⁺ and 1370 keV Pt⁺ ions. At the implanted range, Co and Pt react to form small Co _x Pt_(1?x) nanoparticles during Si⁺ ion irradiation at 300 °C. Thermal annealing of the pre-implanted silica substrate at 1000 °C results in the formation of spherical nanoparticles of various sizes. When irradiated with Si⁺ ions at 300 °C, particles in the size range of 5–17 nm undergo rod-like shape transformation with an elongation in the direction of the incident ion beam, while those particles in the size range of 17–26 nm turn into elliptical shape. Moreover, it is suspected that very big nanoparticles (size >26 nm) decrease in size, while small nanoparticles (size <5 nm) do not undergo any transformation. During Si⁺ ion irradiation, the crystalline nature of the nanoparticles is preserved. The results are discussed in the light of the thermal spike model.     

The decay of theI π=8+ isomer in100Cd-neutron particle and proton hole states

The γ-decay and half life of the t_1/2=60(3) ns I^π=8⁺ isomer in¹⁰⁰Cd have been studied with a recoil catcher setup inside the multidetector π-array OSIRIS. Evaporation neutrons and charged particles from the reaction⁵⁸Ni+⁴⁶Ti were measured in coincidence with delayed γ-rays. Six new γ-ray transitions with intensities of 1–10% of the main γ-ray cascade were found, two new states established and firm spin-parity assignments were made to all states below the isomer. The new states were identified as the 4⁺ and 6⁺ members of the proton πg_9/2 ^?2 multiplet.     

Der Zerfall des Co60m und Zr90m

Co^60m was produced by the reaction Co⁵⁹ (n,γ) Co^60m ; its decay has been investigated by scintillation spectrometers. The half-period has been remeasured yielding a value ofT _1/2=(10·35 ±0·20) min. The isomeric decay mainly leads to the Co⁶⁰ ground state by a (58·6±0·6) keV transition. TheK-conversion coefficientα _K= 41±3 and the total conversion coefficientα=47±3 indicate the transition to beM3 and the spin of Co^60m to be 2⁺. Further Co^60m decays by beta transitions to Ni⁶⁰. The beta component (8·6±1·2)·10^?3%, log ft=7·32 leading to a (2·16±0·02) MeV level has been measured for the first time. A second component (0·24±0·03)%, log ft=7·23 leads to the 1·33 MeV level. The 2·16 MeV level decays to the Ni⁶⁰ ground state mainly by a 0·83–1·33 MeV cascade, in a few cases by a direct transition. The spin of the 2·16 MeV level is 2⁺. Zr^90m was produced by the reaction Zr⁹⁰ (n,n′) Zr^90m . The half-period was measured yielding a value ofT _1/2=(0·83±0·03) sec. Zr^90m decays in the following way: (77±5) % by a direct (2·31±0·02) MeV —E 5 transition to the Zr ground state and (23±5)% by a (132·5±1·5) keV-(2·18±0·03) MeV cascade detected for the first time in the isomeric decay. TheK-conversion coefficient of the 132·5 keV transition isα _k=(2·2±0·3) indicating this transition to beE3 and the spin of the 2·18 MeV level to be 2⁺. The Zr^90m -decay sheme is in accordance with the level sequence of Zr⁹⁰ as measured in the Nb⁹⁰ decay.     

Investigating the Double Beta Decay of <Superscript>58</Superscript>Ni

Double beta decay (β + EC, EC/EC) of ⁵⁸Ni is investigated at France’s Modane Underground Laboratory (4800 m water equivalent) using the OBELIX ultralow-background HPGe detector with a sensitive volume of 600 cm³ and a natural nickel sample of ~68% 58Ni with a mass of ~21.7 kg. After preliminary analysis of the experimental data accumulated over ~144 days, new experimental limits are obtained for the 2νβ⁺EC decay of ⁵⁸Ni to the 0⁺ ground state and the 2 ₁ ⁺ , 811 keV excited state of ⁵⁸Fe, and for the 2νEC/EC decay of ⁵⁸Ni to the 2 ₁ ⁺ , 811 keV and 2 ₂ ⁺ , 1675 keV excited states of ⁵⁸Fe. The limits are T_1/2(β⁺EC,0→0⁺) > 1.7 × 10²² yr, T_1/2(β⁺EC,0→2 ₁ ⁺ ) > 2.3 × 10²² yr, T_1/2(EC/EC,0→2 ₁ ⁺ ) > 3.3 × 10²² yr, and T_1/2(EC/EC,0→2 ₂ ⁺ ) > 3.4 × 10²² yr. Experimental limit T_1/2(0νEC/EC–res, 1918 keV > 4.1 × 10²² yr is obtained for resonant neutrinoless radiative EC/EC decay with an energy of 1918.3 keV. All limits are at 90% CL.     

Interpretation of secondary ion mass spectra by means of fingerprint spectra and secondary ion imaging

A passive layer, of several thousand ? thickness, formed on a polycrystalline nickel electrode, has been examined using secondary ion mass spectrometry (SIMS) by spottering with a 5.5 keV, 13μA·cm⁻²,⁴⁰Ar⁺ primary beam. Concentration profiles were detived by monitoring the intensities of atomic and molecular mass peaks as a function of sputtering time (i.e. depth). Nickel was present throughout the layer but not as the element since the relative intensities of the Ni _n ⁺ (n=1, 2, 3, 4) peaks, constituting part of its fingerprint spectrum, differed from those in the fingerprint spectrum of elemental nickel. These values were eventually reached, signifying piercing of the layer and thus providing a means of estimating its thickness. Imaging of⁵⁸Ni⁺ showed the presence of nickel in at least two different modifications in the layer, both with higher Ni⁺ yields than the bulk nickel. Their fractional coverages were estimated from the images taken at various depths. The resulting profile of the Ni⁺ originating from one of these modifications was found to be proportional to the¹⁶O⁻ profile, indicating that these ions originate from the same molecule. This example demonstrates the advantage of combining different SIMS modes (viz. depth profiles, fingerprint spectra and imaging) in tackling certain analytical problems.     

Electron Paramagnetic Resonance and Electron Spin Echo Studies of Co2+ Coordination by Nicotinamide Adenine Dinucleotide (NAD+) in Water Solution

Co²⁺ binding to the nicotinamide adenine dinucleotide (NAD⁺) molecule in water solution was studied by electron paramagnetic resonance (EPR) and electron spin echo at low temperatures. Cobalt is coordinated by NAD⁺ when the metal is in excess only, but even in such conditions, the Co/NAD⁺ complexes coexist with Co(H₂O)₆ complexes. EPR spin-Hamiltonian parameters of the Co/NAD⁺ complex at 6 K are g _z  = 2.01, g _x  = 2.38, g _y  = 3.06, A _z  = 94 × 10^?4 cm^?1, A _x  = 33 × 10^?4 cm^?1 and A _y  = 71 × 10^?4 cm^?1. They indicate the low-spin Co²⁺ configuration with S = 1/2. Electron spin echo envelope modulation spectroscopy with Fourier transform of the modulated spin echo decay shows a strong coordination by nitrogen atoms and excludes the coordination by phosphate and/or amide groups. Thus, Co²⁺ ion is coordinated in pseudo-tetrahedral geometry by four nitrogen atoms of adenine rings of two NAD⁺ molecules.     

Ion beam synthesis and investigation of nanocomposite multiferroics based on barium titanate with 3d metal nanoparticles

Samples of nanocomposite multiferroics have been synthesized by implantation of Co⁺, Fe⁺, and Ni⁺ ions with an energy of 40 keV into ferroelectric barium titanate plates to doses in the range (0.5–1.5) × 10¹⁷ ions/cm². It has been found that nanoparticles of metallic iron, cobalt, or nickel are formed in the barium titanate layer subjected to ion bombardment. With an increase in the implantation dose, the implanted samples sequentially exhibit superparamagnetic, soft magnetic, and, finally, strong ferromagnetic properties at room temperature. The average sizes of ion-synthesized 3d-metal nanoparticles vary in the range from 5 to 10 nm depending on the implantation dose. Investigation of the orientation dependence of the magnetic hysteresis loops has demonstrated that the samples show a uniaxial (“easy plane”) magnetic anisotropy typical of thin granular magnetic films. Ferromagnetic BaTiO₃: 3d metal samples are characterized by a significant shift of the ferromagnetic resonance signal in an external electric field, as well as by a large (in magnitude) magnetodielectric effect at room temperature. These results indicate that there is a strong magnetoelectric coupling between the ferroelectric barium titanate matrix and ion-synthesized nanoparticles of magnetic metals.     

Laser induced breakdown spectroscopy of germane plasma induced by IR CO2 pulsed laser

Laser-induced breakdown spectroscopy (LIBS) in germane (GeH₄), initially at room temperature and pressures ranging from 2 to 10 kPa, was studied using a high-power transverse excitation atmospheric (TEA) CO₂ laser (λ=10.653 μm, τ _FWHM=64 ns and power densities ranging from 0.28 to 5.52 GW cm⁻²). The strong emission spectrum of the generated plasma is mainly due to electronic relaxation of excited Ge, H and ionic fragments Ge⁺, Ge²⁺ and Ge³⁺. The weak emission is due to molecular bands of H₂. Excitation temperatures of 8100±300 K and 23,500±2500 K were estimated by Ge atomic and Ge⁺ singly ionized lines, respectively. Electron number densities of the order of (0.7–6.2)×10¹⁷ cm⁻³ were deduced from the Stark broadening of several atomic Ge lines. The characteristics of the spectral emission intensities from different species have been investigated as functions of the germane pressure and laser irradiance. Optical breakdown threshold intensities in germane at 10.653 μm have been determined. The mechanism of initiation of the laser-induced plasma in germane has been analyzed.     

Dopant distribution, oxygen stoichiometry and magnetism of nanoscale Sn0.99Co0.01O2

In recent work, we have shown that chemically synthesized Sn_1−xCo_xO₂ nanoscale powders with x≤0.01 are ferromagnetic at room temperature when prepared by annealing the reaction precipitate in the narrow temperature window of 350-600 ^°C. Combined high resolution x-ray photoelectron spectroscopy (on as-prepared and Ar⁺ ion sputtered samples), x-ray diffraction and magnetometry measurements showed that the Co distribution is more uniform throughout the individual Sn_0.99Co_0.01O₂ particles when prepared at lower annealing temperatures of 350-600 ^°C and this uniform dopant distribution is essential to produce stable high temperature ferromagnetism. However, surface segregation of the dopant atoms in samples annealed at >600 ^°C destroys the room-temperature ferromagnetic behavior and reduces the Curie temperature to <300 K.     

Temperature variation of the Debye-Waller factors of metal and halide ions in CsCl-Br solid solutions between room temperature and 90°K by powder X-ray diffraction

Solid solutions of CsCl-Br in different molal concentrations were prepared and X-ray diffractograms taken. The integrated intensities of the Bragg peaks have been estimated and structure factors were obtained. The crystal lattice in each of these solid solution samples is made up of a random distribution of Cs⁺, Cl^? and Br^? ions depending upon the molal concentration. A pseudo-atom model has been proposed in which the Cs⁺ ions occupy (000) position and a pseudo-atom occupies (1/2 1/2 1/2) position. The presence of incoherence scattering in these solid solutions has been considered by applying the necessary correction to the atomic scattering factors. The integrated intensities have been analysed and the temperature variation of the Debye-Waller factors of the metal (Cs⁺) ion and the pseudo ion (CB^?) have been estimated.     

Einstein A coefficients and absolute line intensities for the E2Π–X2Σ+ transition of CaH

Einstein A coefficients and absolute line intensities have been calculated for the E²Π–X²Σ⁺ transition of CaH. Using wavefunctions derived from the Rydberg–Klein–Rees (RKR) method and electronic transition dipole moment functions obtained from high-level ab initio calculations, rotationless transition dipole moment matrix elements have been calculated for all 10 bands involving v′=0,1 of the E²Π state and v″=0,1,2,3,4 of the X²Σ state. The rotational line strength factors (Hönl–London factors) are derived for the intermediate coupling case between Hund's case (a) and (b) for the E²Π–X²Σ⁺ transition. The computed transition dipole moments and the spectroscopic constants from a recent study [Ram et al., Journal of Molecular Spectroscopy 2011;266:86–91] have been combined to generate line lists containing Einstein A coefficients and absolute line intensities for 10 bands of the E²Π–X²Σ⁺ transition of CaH for J-values up to 50.5. The absolute line intensities have been used to determine a rotational temperature of 778±3 °C for the CaH sample in the recent study.