Messung der Wirkungsquerschnitte für die Linienverbreiterung von Hochfrequenzübergängen im 63 P 2-Zustand des Quecksilbers durch Stöße mit Edelgasatomen

The linewidth of high frequency transitions between Zeeman-levels of the metastable 6³ P ₂-state of mercury is measured as function of the pressure of various noble gases. The measurements are made for all noble gases in the pressure range from 10^?3 to about 2 · 10^?2 Torr. The cross sections for linebroadening due to atomic collisions are derived from the pressure dependence of the linewidth. These cross sections σ were found to be (71 ± 10) · 10^?16 cm² for He, (82 ± 10) · 10^?16 cm² for Ne, (153± 12) × 10^?16 cm² for Ar, (204±28) · 10¹⁶ cm² for Kr and (291 ± 41) · 10^?16 cm² for Xe.     

The GaP(001) surface and the adsorption of Cs

GaP(001) cleaned by argon-ion bombardment and annealed at 500°C showed the Ga-stabilized GaP(001)(4 × 2) structure. Only treatment in 10^?5 Torr PH₃ at 500°C gave the P-stabilized GaP(001)(1 × 2) structure. The AES peak ratio $\text{P}\text{Ga}$ is 2 for the (4 × 2) and 3.5 for the (1 × 2) structure. Cs adsorbs with a sticking probability of unity up to 5 × 10¹⁴ Cs atoms cm^?2 and a lower one at higher coverages. The photoemission measured with uv light of 3660 Å showed a maximum at the coverage of 5 × 10¹⁴ atoms cm^?2. Cs adsorbs amorphously at room temperature, but heat treatment gives ordered structures, which are thought to be reconstructed GaP(001) structures induced by Cs. The LEED patterns showed the GaP(001)(1 × 2) Cs structure formed at 180°C for 10 h with a Cs coverage of 5 × 10¹⁴ atoms cm^?2, the GaP(001)(1 × 4) Cs formed at 210°C for 10 hours with a Cs coverage of 2.7 × 10¹⁴ atoms cm^?2, the GaP(001)(7 × 1) and the high temperature GaP(001)(1 × 4), the latter two with very low Cs content. Desorption measurements show three stability regions: (a) between 25–150°C for coverages greater than 5 × 10¹⁴ atoms cm^?2, and an activation energy of 1.2 eV; (b) between 180–200°C with a coverage of 5 × 10¹⁴ atoms cm^?2, and an activation energy of 1.8 eV; (c) between 210–400°C with a coverage of 2.7 × 10¹⁴ atoms cm^?2, and an activation energy of 2.5 eV.     

Synthesis and Characterization of New Light Emitter Symmetrical Phenoxazinium Salt and Its Potential Application as Sensor for Assessment of Hg2+

The sensitization of the excited triplet state of a novel symmetrical Bis(dialkylamino)phenoxazinium salt was developed in the presence of Hg²⁺. This effect was used to determine the concentration of Hg²⁺ in different water samples. The phenoxazinium salt sensor was characterized by different spectroscopic tools such as: UV, FTIR, NMR and fluorescence spectra. The sensor has an emission band at 347 nm in DMSO. Hg²⁺ in DMSO at pH 5.6 can remarkably quench the fluorescence intensity of the sensor at 347 nm and a new band was appeared at 436 nm due to the strong complex formation between Hg²⁺ and sensor. The quenching of the band intensity at 347 and the enhancement of the intensity of the new band at 436 were used to determine the Hg²⁺ in different waste water samples. The dynamic range found for the determination of Hg²⁺ concentration is 8.7?×?10^-10 – 1.4?×?10^-6 mol L^?1 with a detection limit of 5.8?×?10^?10 mol L^?1 and quantification detection limit of 1.8?×?10^-9 mol L^-1.     

Lithium diffusion in Li<Subscript>3</Subscript>V<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>-based electrodes: a joint analysis of electrochemical impedance,cyclic voltammetry,pulse chronoamperometry,and chronopotentiometry data

In order to establish the mechanism and to determine the parameters of lithium transport in electrodes based on lithium-vanadium phosphate (Li₃V₂(PO₄)₃), the kinetic model was designed and experimentally tested for joint analysis of electrochemical impedance (EIS), cyclic voltammetry (CV), pulse chronoamperometry (PITT), and chronopotentiometry (GITT) data. It comprises the stages of sequential lithium-ion transfer in the surface layer and the bulk of electrode material’s particles, including accumulation of lithium in the bulk. Transfer processes at both sites are of diffusion nature and differ significantly, both by temporal (characteristic time, τ) and kinetic (diffusion coefficient, D) constants. PITT data analysis provided the following D values for the predominantly lithiated and delithiated forms of the intercalation material: 10^?9 and 3 × 10^?10 cm² s^?1, respectively, for transfer in the bulk and 10^?12 cm² s^?1 for transfer in the thin surface layer of material’s particles. D values extracted from GITT data are in consistency with those obtained from PITT: 3.5–5.8 × 10^?10 and 0.9–5 × 10^?10 cm² s^?1 (for the current and currentless mode, respectively). The D values obtained from EIS data were 5.5 × 10^?10 cm² s^?1 for lithiated (at a potential of 3.5 V) and 2.3 × 10^?9 cm² s^?1 for delithiated (at a potential 4.1 V) forms. CV evaluation gave close results: 3 × 10^?11 cm² s^?1 for anodic and 3.4 × 10^?11 cm² s^?1 for cathodic processes, respectively. The use of complex experimental measurement procedure for combined application of the EIS, PITT, and GITT methods allowed to obtain thermodynamic E,c dependence of Li₃V₂(PO₄)₃ electrode, which is not affected by polarization and heterogeneity of lithium concentration in the intercalate.     

Messung der Lebensdauer angeregter Kernniveaus von Al28, Cs133, Pr141, W182 und Pt195

The halflife of excited states in some nuclei has been measured by the method of delayed coincidences. Two different experimental arrangements have been used: a conventional scintillation counter equipment and a fast gasfilled parallelplate avalanche-counter. The results of these measurements are: 31 keV-level in Al²⁸:T _1/2=(1.91±0.08) · 10^?9 sec, 81 keV-level in Cs¹³³:T _1/2=(6.25±0.05) · 10^?9 sec, 145 keV-level in Pr¹⁴¹:T _1/2=(1.85±0.03) · 10^?9 sec, 100keV-level in W¹⁸²:T _1/2=(1.45±0.04) · 10^?9 sec, 1290 keV-level in W¹⁸² T _1/2=(1.05±0.03) · 10^?9 sec, 99 keV-level in Pt¹⁹⁵:T _1/2≦1.6 · 10^?10 sec, 129 keV-level in Pt¹⁹⁵:T _1/2=(6.2±0.7) · 10^?10 sec. These experimental values are discussed and compared with theoretical model predictions.     

I. Electron-impact ionization and dissociation of C<Subscript>2</Subscript>H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and C<Subscript>2</Subscript>D<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>

Absolute cross-sections for electron-impact ionization and dissociation of C₂H₂⁺ and C₂D₂⁺ have been measured for electron energies ranging from the corresponding thresholds up to 2.5 keV. The animated crossed beams experiment has been used. Light as well as heavy fragment ions that are produced from the ionization and the dissociation of the target have been detected for the first time. The maximum of the cross-section for single ionization is found to be (5.56 ± 0.03)× 10^-17 cm² around 140 eV. Cross-sections for dissociation of C₂ H₂⁺ (C₂D₂⁺) to ionic products are seen to decrease for two orders of magnitude, from C₂D⁺ (12.6 ± 0.3) × 10^-17 cm² over CH⁺(9.55 ± 0.06) × 10^-17 cm², C⁺ (6.66 ± 0.05) × 10^-17 cm², C₂⁺ (5.36 ± 0.27) × 10^-17 cm², H⁺ (4.73 ± 0.29) × 10^-17 cm² and CH₂⁺ (4.56 ± 0.27) × 10^-18 cm² to H₂⁺ (5.68 ± 0.49) × 10^-19 cm². Absolute cross-sections and threshold energies have been compared with the scarce data available in the literature.     

Investigation of irradiated and annealed high-temperature superconducting films with the Umka nanotechnological complex

Superconducting YBa₂Cu₃O_{7 ? x} films were fabricated by dc magnetron sputtering. They were irradiated with 1.2-MeV He⁺ ions to doses of 4 × 10¹⁵, 8 × 10¹⁵, 16 × 10¹⁵, and 32 × 10¹⁵ cm^?2. The irradiated films were subjected to stepwise (30 min per step) vacuum annealing at 500, 600, 700, 800, and 900°C. After vacuum annealing, the samples irradiated to doses of 4 × 10¹⁵, 8 × 10¹⁵, and 16 × 10¹⁵ cm^?2 exhibited partial recovery of their critical temperature, whereas the sample with a dose of 32 × 10¹⁵ cm^?2 exhibited no signs of partial recovery of T _C. Investigation of the irradiated annealed samples with the Umka nanotechnological complex has revealed damaged surface regions extended to a relatively large (several tenths of a micrometer) depth.     

Effect of residual atmospheric pressure on the development of electrostatic discharges at the surface of protective glasses of solar cells

Electrostatic discharges obtained upon the irradiation of K-208 glass with 40-keV electrons at a flux density φ of 10¹⁰ to 2 × 10¹¹ cm^–2 s^–1 are studied. The residual pressure p _v in the vacuum chamber is varied from 5 × 10^–5 to 5 × 10^–3 Pa. Structural changes in the sample surfaces are studied by atomic-force microscopy. Depending on the pressure level, two types of discharges are observed in experiments at 3 × 10¹⁰ ≤ φ ≤ 1.2 × 10¹¹ cm^–2 s^–1: a microprojection at the glass–ionized-residual-atmosphere surface and a discharge which develops along the irradiated surface. It is found that at 5 × 10^–5 ≤ p _v ≤ 3 × 10^–4 Pa and 8 × 10¹⁰ ≤ φ ≤ 10¹¹ cm^–2 s^–1, discharges of the first type appear at the beginning of exposure; that is, an increase in microprojections is observed. Further, surface discharges propagate through these microprojections. At 10^–3 ≤ p _v ≤ 5 × 10^–3 Pa and 10¹⁰ ≤ φ ≤ 5 × 10¹⁰ cm^–2 s^–1, on the contrary, discharges of the second type are realized at the beginning. These discharges result in the appearance of channels with inhomogeneities on the glass, at which subsequently discharges of the first type occur. It is determined by calculations that in the region adjacent to the exposed glass surface, secondary electrons accelerated in a field of charge accumulated in the glass make the main contribution to the ionization of gases.     

Enhancement in electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes by 100 MeV Si9+ swift heavy ion irradiation

Swift heavy ion (SHI) irradiation has been used as a tool to enhance the electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes dispersed with dedoped polyaniline (PAni) nanorods; 100 MeV Si⁹⁺ ions with four different fluences of 5?×?10¹⁰, 1?×?10¹¹, 5?×?10¹¹, and 1?×?10¹² ions cm^?2 have been used as SHI. XRD results depict that with increasing ion fluence, crystallinity decreases due to chain scission up to fluence of 5?×?10¹¹ ions cm^?2, and at higher fluence, crystallinity increases due to cross-linking of polymer chains. Ionic conductivity, electrochemical stability, and dielectric properties are enhanced with increasing ion fluence attaining maximum value at the fluence of 5?×?10¹¹ ions cm^?2 and subsequently decrease. Optimum ionic conductivity of 1.5?×?10^?2 S cm^?1 and electrochemical stability up to 6.3 V have been obtained at the fluence of 5?×?10¹¹ ions cm^?2. Ac conductivity studies show that ion conduction takes place through hopping of ions from one coordination site to the other. On SHI irradiation, amorphicity of the polymer matrix increases resulting in increased segmental motion which facilitates ion hopping leading to an increase in ionic conductivity. Thermogravimetric analysis (TGA) measurements show that SHI-irradiated nanocomposite polymer electrolytes are thermally stable up to 240–260 °C.     

Ion-molecule collisions in gaseous111InCl and111InI systems

Using gaseous sources of¹¹¹InCl and¹¹¹InI with densities between 1.0·10¹⁷ cm^?3 and 4.4·10¹⁹ cm^?3 the perturbation of the 171.3–245.4 keVγ-γ cascade was measured as a function of time and density by the time-differential perturbed angular correlation (TDPAC) method. The anisotropy shows a strong dependence on the density. By means of an extended model based on a stochastic model of Bosch and Spehl collision cross sections for charge transfer and deorientation could be determined. The cross sections for charge transfer collisions were within the region from 2·10^?15 cm² to 26·10^?15 cm² and for deorientation collisions between 1·10^?15 cm² and 100·10^?15 cm².     

The effects of fast-neutron irradiation on tensile strengths of carbon fibers

Two types of commercially available carbon fibers (high tensile strength, HTS, and high modulus, HMS) were irradiated in the Ground Test Reactor in environments of air and of liquid nitrogen (LN₂). The tensile strength of HTS fibers irradiated in air increased sharply above a fast-neutron fluence of 6 × 10¹⁷ n/cm² (E> 1 MeV) and was 17 per cent greater than the strength of unirradiated control fibers at a fluence of 8.5 × 10¹⁷ n/cm², but then the strengrh began to decrease for additional neutron exposure in air and fell 25 per cent below the control strength at the highest fluence of 4.5 × 10¹⁸ n/cm². However, when irradiated in LN₂ where surface oxidation did not take place, the room-temperature strength of HTS fibers continued to increase beyond 8.5 × 10¹⁷ n/cm² and became almost 30 per cent greater than the control strength for a fluence of 3 × 10¹⁸ n/cm². The tensile strength of HMS fibers irradiated in air increased slowly but steadily with neutron exposure and was only 4 per cent greater than the control strength at the highest fluence of 4.5 × 10¹⁸ n/cm²; the room-temperature strength of the HMS fibers decreased by 13 per cent when irradiated to a fluence of 3 × 10¹⁸ n/cm² in LN₂.     

The near surface changes in boron implanted 4145 steel

Boron implanted 4145 steel was evaluated for changes in the near-surface region property such as microhardness. The surfaces when implanted with ¹¹B⁺ ions at 135 keV energy to a dose 1 × 10¹⁷ ions cm^?2 resulted in increase of microhardness for 10 to 40 gms of applied load. An increase upto 40% in microhardness could be observed in the specimen when annealed at 310δC for 3 hours. Furthermore, the effect of ion-beam induced intermixing of 250Å thin carbon film due to boron implantation was also studied for different doses ranging from 1 × 10¹⁷ to 3 × 10¹⁷ boron ions cm^?2. An increase in microhardness with applied load was observed for 1 × 10¹⁷ ions cm^?2 concentration, while hardest layer was formed at 3 × 10¹⁷ ions cm^?2 dose which practically had very little effect to 10 and 20 gms of load.     

Interatomic force constants studies of AMF3perovskite-type crystals (A = K,Rb; M = Mg,Ni, Co,Zn, Mn)

A simple model involving only three force constants allows us to evaluate the short range interactions in perovskite fluorides from the experimental values of the elastic constants and the lattice parameters of these compounds. The results indicate that the A-F bonds are quite central in character whereas the M-F bonds are axially symmetric; thus the short range A-F interactions are assumed to have the Born-Mayer form:ZZZZZBy studying the variations of the force constants with respect to the lattice parameter r, it is determined that ρ = 0·232 , λ = 2·8 × 10^?8 ergs for K⁺-F^?; ρ = 0·232 , λ = 4·1 × 10^?8 ergs for Rb⁺-F^?; λ₂, ρ₂ and ρ₂ are respectively 6·9 × 10^?10 ergs, 0·34 , 0·98for Co²⁺-F^? and 2·9 × 10^?10 ergs, 0·46 , 1·40for Mn²⁺-F^?. Taking into account both the short range repulsive potential and the long range electrostatic potential we can study the variations of the lattice energy as a function of r near the equilibrium position and deduce a theoretical value of the lattice distance. In spite of the simplicity of the model, the discrepancy between the experimental and the theoretical values is less than 10 per cent for all the compounds.     

New measurement of (g−2) of the Muon

The g-factor anomaly, a≡(g?2)/2, has been measured for μ⁺ in the new Muon Storage Ring at CERN. The result is a = (1 165 895 ± 27) × 10^?9. This is (13 ± 29) × 10^?9 below the theoretical value which includes sixth-order QED terms and a hadronic contribution of (73 ± 10) × 10^?9.     

Carbonization in boron-ion-implanted polymethylmethacrylate as revealed from Raman spectroscopy and electrical measurements

ABSTRACT

The results of Raman spectroscopy and electrical measurements of 40 keV boron-ion-implanted polymethylmethacrylate with ion doses from 6.25 × 10¹⁴ to 5.0 × 10¹⁶ ions/cm² are reported for the first time. The Raman spectra recorded in the 400–3800 cm^?1 range, showing the formation of new carbon–carbon bands for the as-implanted samples at higher ion doses (>10¹⁶ ions/cm²), are found to be an additional support for carbonization processes earlier revealed by slow positrons. The current–voltage dependences at 360 K testify also that the as-implanted samples examined with higher fluences (3.75 × 10¹⁶ and 5.0 × 10¹⁶ ions/cm²) have created a very thin conductive layer or conductive joints due to carbonization.     

Spectral characteristics and nonlinear studies of methyl violet 2B dye in liquid and solid media

Solid-state dye-doped polymers are attractive alternatives to the conventional liquid-dye solutions. In this paper, the spectral characteristics and nonlinear properties of the dye Methyl violet 2B has been studied. The third-order nonlinear optical properties of Methyl violet 2B dye in ethanol and a dye-doped polymer film were measured by the Z-scan technique. This material exhibits a negative optical nonlinearity. The dye exhibited a nonlinear refractive coefficient (n ₂ = ?4.14 × 10^?7 and ?4.291 × 10^?7 cm²/W in liquid and solid media, respectively), nonlinear absorption coefficient (β = ?4.634 × 10^?3 and ?4.66 × 10^?3 cm/W in liquid and solid media, respectively), and susceptibility (χ⁽³⁾ = 1.88 × 10^?5 and 1.963 × 10^?5 esu in liquid and solid media, respectively). These results show that Methyl violet 2B dye has potential applications in nonlinear optics.     

Mössbauer Characterization of Iron-Based Nanogranular Films

The electric field gradients (EFG) of the Hf₂Fe intermetallic compound were calculated using the full-potential linearized augmented plain-wave (FP-LAPW) method as embodied in the WIEN 97 code. The obtained values are compared with other ab-initio calculations and on a qualitative basis with the previously reported experimental data obtained from TDPAC. The calculated results, −23.1·10²¹ V/m² and 2.7·10²¹ V/m² for Hf 48f and Fe 32e position, respectively, are in excellent agreement with experimental data (23.4·10²¹ V/m² and 2.7·10²¹ V/m²), better than those reported in earlier calculations. The calculated EFG for Hf 16c position (4.2·10²¹ V/m²) is stronger than the experimental one (1.1·10²¹ V/m²).     

埋氧注氮工艺对部分耗尽SOI PMOSFET顶栅氧的辐射硬度的影响

研究了埋氧注氮对部分耗尽SOI PMOSFET顶栅氧的总剂量辐射硬度所造成的影响。注入埋氧的氮剂量分别是8×1015 , 2×1016 和1×1017cm-2。实验结果表明，辐照前，晶体管的阈值电压随氮注入剂量的增加向负方向漂移。在正2V的栅偏压下，经5×105 rad(Si)的总剂量辐照后，同埋氧未注氮的晶体管相比，埋氧注氮剂量为8×1015 cm-2的晶体管呈现出了较小的阈值电压漂移量。然而，当注氮剂量高达2×1016 和 1×1017cm-2时，所测大多数晶体管的顶栅氧却由于5×105 rad(Si)的总剂量辐照而受到了严重损伤。另外，对于顶栅氧严重受损的晶体管，其体-漏结也受到了损伤。所有的实验结果可通过氮注入过程中对顶硅的晶格损伤来解释。     

Determination of the negative hydrogen ion concentration in a cesium-hydrogen discharge

The concentration N _H ⁻ of negative hydrogen ions in a low-voltage cesium-hydrogen discharge plasma N _H ⁻ is determined from experiments with laser radiation absorption caused by the photodetachment of electrons from the H⁻ ions. The resolution of a setup measuring the relative absorption is ≥10⁻⁵ for a signal-to-noise ratio of ∼10⁻² or less. A heated-cathode diode is used to initiate the discharge at a voltage of U≤10 V and a current density of j≤5 A/cm² (hydrogen pressure p _{H 2} is equal to several torr, and the cesium concentration in the plasma N _Cs ⁽⁰⁾ ∼10¹⁴ cm⁻³). The absorption due to the photoionization of excited Cs atoms is shown to be negligible. The measured concentration N _H ⁻ of the H⁻ ions is 10¹²–10¹³ cm⁻³. Experimental results are consistent with the theory.