The Spectrum of Doubly Ionized Tungsten (W III)

The spectrum of doubly ionized tungsten (W III) was produced in a sliding-spark discharge and recorded photographically on the NIST 10.7-m normal-incidence vacuum spectrograph in the 600–2680 Å spectral region. The analysis has led to the establishment of 71 levels of the interacting 5d⁴, 5d³ 6s and 5d² 6s² even configurations and 164 levels of the interacting 5d³ 6p and 5d² 6s 6p odd ones. A total of 2636 lines have been classified as transitions between the 235 experimentally determined levels. Comparison between the observed levels and those calculated from matrix diagonalizations with least-squares fitted parameters shows an rms deviation of ±87 cm⁻¹ for the even configurations and ±450 cm⁻¹ for the odd ones.     

Analysis of the Spectrum of Doubly Ionized Molybdenum (Mo III)

The spectrum of doubly ionized molybdenum (Mo III) was produced in a sliding spark discharge and recorded photographically on the NIST 10.7-m normal incidence spectrograph in the 800-3250 Å spectral region. The analysis has led to the establishment of 76 levels of the interacting 4d⁴, 4d³ 5s and 4d² 5s² even configurations, 73 levels of the interacting 4d³ 5d and 4d³ 6s even configurations, and 181 levels of the interacting 4d³ 5p and 4d² 5s5p odd configurations. Approximately 3100 lines have been classified as transitions between these experimentally determined levels. Comparison between the observed levels and those calculated from matrix diagonalizations with least-squares fitted parameters shows standard deviations of 44, 33, and 183 cm⁻¹, respectively, for the levels of the three sets of configurations.     

Low Even Configurations in the First Spectrum of Ruthenium (Ru I), part 2

A published calculation for the 4d⁸, 4d ⁷5s, and 4d⁶ 5s² configurations of Ru I (R. E. Trees, J. Opt. Soc. Am. 49, 838 (1959).) is repeated in steps. Displacements produced by configuration interaction are evaluated, and departures of term positions from familiar expectations in the absence of configuration interaction are explained. The weaker perturbations produced by second-order effects of the spin-orbit interaction are then determined. It is shown that the neglect of these effects in published hand computations has obscured the remarkably good agreement between theory and observation that is obtainable in spectra of the second long period. The eigenvectors are based on “third-order eigenfunctions” which describe the levels simply, and show the degree of LS-coupling in a more quantitative manner.     

Analysis of the (5d2+5d6s)–5d6p Transition Arrays of Os VII and Ir VIII,and the 6s 2S–6p 2P Transitions of Ir IX

The spectra of osmium and iridium were photographed in the 300 Å to 1600 Å region on a 3 m normal incidence spectrograph using a triggered spark source. The (5d² + 5d6s)–5d6p transition arrays of Os VII and Ir VIII were analyzed. All levels of these three configurations in both spectra have been established. There are 77 lines in Os VII and 71 lines in Ir VIII classified. The parametric least squares fitting calculations are used to interpret both spectra. The 6s ²S_1/2–6p ²P_1/2,3/2 transitions in Ir IX have also been identified.     

Analysis of the Spectrum of Neutral Atomic Bromine (Br I)

The spectrum of the neutral bromine atom, Br I, has been newly investigated by using electrodeless discharge tubes as light sources. The observations have led to a list of wavelengths and estimated intensities for 1253 spectral lines in the range 1067 to 24100 Å. The number of known energy levels has been increased to 123 even and 128 odd levels, as compared with the 27 even and 33 odd levels previously known. All predicted energy levels of the 4s²4p⁴ns, up, nd, nf electron configurations from 0 to ~93250 K have been discovered. The observations in the vacuum ultraviolet establish that the positions of all the levels lying above those of the ground configuration as given in the compilation Atomic Energy Levels, Vol. II (1952) should be increased by 6.7 K. All but 26 faint lines of Br I have been classified. A total of 67 levels has been ascribed to the 4s² 4p* nf configurations. It is demonstrated that the nf configurations exhibit almost pure pair coupling. The very regular (³P₂)nf[5]°_11/2 series yields for the principal ionization energy of Br I the value 95284.8 K.     

Description and Analysis of the First Spectrum of Iodine

An extensive survey of the spectra of iodine has led to a list of more than 900 lines emitted by neutral atoms in the region from 23070 A in the infrared to 1195 A in the extreme ultraviolet. Wavelengths between 12304 A and 2061 A were derived from measurements of spectrograms obtained with gratings of high dispersion. Wavelengths of lines outside these limits are the computed values for lines observed on photometric tracings of the infrared, inaccessible to photography, and in the ultraviolet with a vacuum-grating spectrograph. For many of the lines Zeeman patterns were obtained in a magnetic field of about 37,000 oersteds. With these data many of the lines have been classified as combinations between odd levels from the electron configurations 5s² 5p⁴ np and 5s² 5p⁴ nf, and even levels from the configurations 5s² 5p⁴ ns and 5s² 5p⁴ nd. Among these levels several sets have been recognized as forming Rydberg sequences that are in close agreement in placing the ground state 5p⁵ 2P1½o of I i at 84,340 cm⁻¹ below the ground state 5p^{4 3}P₂ of I ii. This gives 10.45 electron-volts for the ionization potential of the neutral iodine atom. A strong infrared line at 13148.8 A is explained as a magnetic dipole transition between the levels of the ground term 5p^{5 2}P°.     

Interlaboratory Comparison of Magnetic Thin Film Measurements

A potential low magnetic moment standard reference material (SRM) was studied in an interlaboratory comparison. The mean and the standard deviation of the saturation moment m_s, the remanent moment m_r, and the intrinsic coercivity H_c of nine samples were extracted from hysteresis-loop measurements. Samples were measured by thirteen laboratories using inductive-field loopers, vibrating-sample magnetometers, alternating-gradient force magnetometers, and superconducting quantum-interference-device magnetometers. NiFe films on Si substrates had saturation moment measurements reproduced within 5 % variation among the laboratories. The results show that a good candidate for an SRM must have a highly square hysteresis loop (m_r/m_s > 90 %), H_c ≈ 400 A·m⁻¹ (5 Oe), and m_s ≈ 2 × 10⁻⁷ A·m² (2 × 10⁻⁴ emu).     

The Spectrum of Singly Ionized Atomic Iodine (I ii)

The I ii spectrum has been excited in electrodeless lamps and photographed from 655 A to 11084 A. Wavelengths and estimated intensities are given for almost 2,400 lines. A revision and extension of the earlier analyses of this spectrum has increased the number of known even levels from 43 to 124, and the number of odd levels from 55 to 190. New g_J-factors are given for 46 levels, and the previous designations of 40 levels are changed. Improved measurements in the vacuum ultraviolet region give a correction of 7.4 cm⁻¹ to be subtracted from the values listed in Atomic Energy Levels, Vol. 3 (1958), for all levels above the ground configuration. The approximately 1,800 classified lines now include all of the strongest lines. The ¹S₀ of the ground configuration 5s²5p⁴ has been found, and this configuration has been fitted to intermediate coupling theory. Magnetic dipole transitions between levels of the ground configuration, ³P₂–¹D₂ (7282 A) and ³P₁–¹S₀ (4460 A), have been observed and their nature confirmed by the Zeeman effect. The line 5p^{4 3}P₂–¹D₂ shows hyperfine structure which is in approximate agreement with a theoretical calculation of the expected structure. New levels have been found for almost all higher configurations. All previously known series have been extended and new ones found. From one of the new series, 5p3(4S°)5−12g5G6°, the principal ionization energy for I ii (154304 ±1 cm⁻¹) has been derived. The results of the analysis are compared with theoretical expectations in a number of cases.     

The optical characteristics of laser-erosion silver plasma

The near-threshold optical emission in the 220-to 600-nm wavelength range from laser-erosion silver plasma was studied. The plasma was generated by a pulsed laser radiation with λ=1.06 mm and a beam power density of (1–3) ×10⁸ W cm^?2 focused on the surface of a massive silver target. The main emission lines are due to the Ag(I) resonances with λ=328.1 and 338.8 nm. A bottle-neck of the recombination flux populating the upper energy states of silver atoms in the 7d ² D _5/2 AgI level of Ag(I). The main flux of the recombination reaction Ag⁺+2e→Ag*+e passes sequentially through the following levels of Ag(I): 7d→6d→5d→5s. The results can be used to increase the quality of thin silver films and to optimize the process of depositing films of complex compositions by laser erosion of the crystal targets of the AgGa(Al,In)S(Se)₂ type.     

Cross Sections of Excitation of Singlet F-Series of Barium Atom by Electron Impact

The excitation of singlet F-levels of barium atom by electron impact is experimentally studied. Manifestations of strong perturbations in the 6s5d ¹ D ₂–6snf ¹ F ^º ₃ spectral series are observed. The dependence of the excitation cross sections on the principal quantum number of the upper level in the 6s5d ¹ D ₂–5dnp ¹ F ^º ₃ spectral series follows the power law in the range n = 6–8. The obtained results are compared with those of the previous experiment.     

Magnetic properties of nanosized Sr2CrReO6 powders prepared by a combustion synthesis process

Double perovskite, Sr₂CrReO₆, nanoparticles in the size range 10–25 nm have been prepared by a combustion method. Its coercivity (H_c) at 5 and 300 K are determined to be 16.1 and 6.5 kOe, respectively. Using the law of approach to saturation, the obtained saturation magnetization σ_s (5 K) and σ_s (300 K) are 0.41 and 0.32 μB per formula unit (f.u.), respectively. The values of saturation magnetization are lower than the expected value 1 μB/f.u. considering the antiferromagnetic coupling between Cr³⁺ (3d³, S = 3 / 2) and Re⁵⁺ (5d², S = 1). At the same time high field irreversibility in M(H) curves and zero field cooled–field cooled (ZFC–FC) processes has also been found. A field-cooled (FC) hysteresis loop shift decreases with increasing temperature and vanishes near 350 K. It is suggested that the observed reduction of σ_s and shifted hysteresis loops are caused by the exchange interaction between the ferromagnetic core of the Sr₂CrReO₆ nanoparticles and its surface layer with disordered spins.     

The size effect of the martensitic transformation in ZrO2-containing ceramics

The relationship between the starting temperature of the martensitic transformation, M _s, and the grain size of the parent phase, d, in ZrO₂-containing ceramics was investigated. The experimental results showed that in tetragonal zirconia polycrystals doped with CeO₂ (8 mol%) and Y₂O₃ (0.25 mol%) (8Ce, 0.25Y-TZP), the M _s temperature displays a linear relationship with d ^–1/2, its slope being negative. A new explanation for this phenomenon, the so-called the size effect, has been presented, in which the grain size of the parent phase affects the M _s temperature through the strength of the parent phase. Thermodynamic calculation of the relationship between M _s and d gives a result consistent with the experimental ones.     

On the mechanism of the electron-impact excitation of 4d 95s 2 2 D 5/2, 3/2 upper laser levels in cadmium ions

The energy dependence of the effective cross sections for the electron-impact excitation of 4d ⁹5s ^{2 2} D _{5/2, 3/2} ? 4d ¹⁰5p ² P ₁ ^{2, 3/2/0} laser transitions in cadmium ions was studied by a high-precision spectroscopic technique using crossed electron and ion beams. The absolute effective cross sections for the laser line excitation at λ=441.6 and 325.0 nm have the peak values 2.5× 10^?16 and 1.3×10^?16 cm², respectively. It is shown that population of the 4d ⁹5s ^{2 2} D _{5/2, 3/2} upper laser levels by the electron impact on cadmium ions in the 4d ¹⁰5s ² S _1/2 ground state takes place predominantly due to the resonance processes; that is, it proceeds via atomic and ionic autoionization states.     

Low-energy tensile-impact behavior of superelastic NiTi shape memory alloy wires

Superelastic property of shape memory alloys (SMAs) is becoming increasingly important for impact applications due to their large recoverable strains and high capacity to dissipate energy. In this work, tensile behavior of superelastic NiTi SMA wires at impact strain rates was studied by instrumented tensile-impact technique, which allows to obtain material properties on the order of 1–10² s⁻¹. The results show that even at impact strain rates, martensite can be induced by tension in NiTi. At impact, a plateau stress appears during transformations similar to that at quasi-static strain rates, but 100–150 MPa higher in stress. This is due to the higher temperatures achieved during the deformation due to the close to adiabatic nature of the impact event. The influence of the strain rate over the mechanical behavior of NiTi was spread to the quasi-static strain rates so that the evolution of several parameters was also studied on the range 10⁻⁵–10² s⁻¹. Therefore, forward stress-induced martensitic (SIM) transformation stresses (σ^Ms and σ^Mf) and deformation energy (E_d) increase with strain rate, but they are strain rate independent from 10⁻¹ s⁻¹ at least until 10² s⁻¹. Reverse SIM transformation stresses (σ^As and σ^Af), recoverable strain energy (E_r), and dissipated energy (W_d) depend mainly on maximum strain achieved during the deformation, but for strains corresponding to a load–unload cycle with complete SIM transformation, σ^As, σ^Af and E_r are higher at impact than at quasi-static strain rates, and W_d shows similar values at very low strain rates and at impact.     

Mass Spectrometric Study of Photoionization. I. Apparatus and Initial Observations on Acetylene,Acetylene-d2, Benzene,and Benzene-d6

A windowless vacuum ultraviolet monochromator and mass spectrometer are combined for the study of photoionization processes in the energy range 2000 to 600 A (6 to 21 eV). Details of the apparatus and techniques of operation are given and results are reported for an initial study of acetylene, acetylene-d₂, benzene, and benzene-d₆. Ionization energies of 11.406 and 11.416 eV are obtained for the 1π_u electron of C₂H₂ and C₂D₂, respectively. Vibrational levels of the ground state of the ion are observed with quantum intervals of 1855 cm⁻¹(C₂H₂) and 1775 cm⁻¹(C₂D₂). Ionization energies for the e_1g(π) electron of C₆H₆ and C₆D₆ are determined to be 9.24₂ and 9.24₅ eV, respectively. Quantum intervals for vibrational levels of the ground state ions are apparently equal for the two isotopic molecules and estimated to be 800 cm⁻¹. A second onset of ionization is observed at 11.5₃ eV for C₆H₆ and at 11.5₉ eV for C₆D₆. Results agree well with spectroscopic data.     

Thermal-lens study of thermo-optical properties of tellurite glasses

Mode-mismatched Thermal Lens (TL) measurements were performed in 70TeO₂–19WO₃–7Na₂O–4Nb₂O₅ (% mol) tellurite glasses doped with either Er³⁺ or Tm³⁺ and co-doped with Er³⁺/Tm³⁺ ions. Thermo-optical parameters (D, K, ds/dQ and ds/dT) were obtained in function of thulium concentrations (0.39–1.6) × 10 ²⁰ ions/cm³. For Er³⁺/Tm³⁺ co-doped tellurite glasses, D and K values are practically independent of the Tm³⁺ concentrations used in this study. The average values of D and ds/dT obtained for tellurite glasses are: (3.1 ± 0.2) × 10⁻³ cm²/s and (16 ± 3) × 10⁻⁶ K⁻¹, respectively.     

Sorption-diffusion model of 137Cs uptake by a water body bottom in estimations of water contamination

For a sample including 22 lakes, the ¹³⁷Cs concentrations in water were determined by the sorption-diffusion model. The ¹³⁷Cs levels in waters of lakes of the Kola Peninsula and Karelian Isthmus are satisfactorily described by the suggested model at the distribution coefficient K _d of 4000 L kg^?1 and diffusion coefficient D of 1.0 × 10^?7 cm² s^?1 for 2–4-year exposure. For mid-latitude lakes, the ranges of K _d and D of ¹³⁷Cs were 6000–1200 L kg^?1 and 1.0 × 10^?7–0.2 × 10^?7 cm² s^?1, respectively. The ¹³⁷Cs concentration in water is determined by the major contribution of silts, which are characterized by high K _d of ¹³⁷Cs and by large thickness of sediments on the bottom of lake hollows, to the watter-bottom sorption system. After 2-year exposure of “Chernobyl” ¹³⁷Cs in lakes, its inventory in water relative to the amount that fell out in 1986 did not exceed 14% for deep lakes and 2–3.6% for shallow lakes.     

Biosynthesis of gold nanoparticles using fungus Trichoderma sp. WL‐Go and their catalysis in degradation of aromatic pollutants

An efficient green method of gold nanoparticles (AuNPs) biosynthesis was achieved by cell‐free extracts of fungus Trichoderma sp. WL‐Go. Based on UV–Vis spectra, AuNPs biosynthesised by cell‐free extracts with 90 mg/l protein exhibited a characteristic absorption band at 556 nm and was stable for 7 days. Transmission electron microscopy images revealed that the as‐synthesised AuNPs were spherical and pseudo‐spherical, and the average size was calculated to be 9.8 nm with a size range of 1–24 nm. The AuNPs illustrated their good catalytic activities for reduction of nitro‐aromatics (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐nitroaniline, 3‐nitroaniline) with catalytic rate constants of 7.4 × 10⁻³ s⁻¹, 10.3 × 10⁻³ s⁻¹, 4.9 × 10⁻³ s⁻¹, 5.8 × 10⁻³ s⁻¹, 15.0 × 10⁻³ s⁻¹, respectively. Meanwhile, the AuNPs also showed excellent catalytic performance in decolourisation of azo dyes with decolourisation efficiency from 82.2 to 97.5%. This study provided a green gentle method for AuNPs synthesis as well as exhibiting efficient catalytic capability for degradation of aromatic pollutants.Inspec keywords: catalysts, dyes, particle size, reduction (chemical), nanobiotechnology, nanofabrication, ultraviolet spectra, gold, transmission electron microscopy, nanoparticles, proteins, catalysis, visible spectra, pollution control, microorganismsOther keywords: nitro‐aromatics, catalytic rate constants, decolourisation efficiency, green gentle method, efficient green method, gold nanoparticles biosynthesis, cell‐free extracts, UV–Vis spectra, characteristic absorption band, transmission electron microscopy images, as‐synthesised AuNPs, catalytic performance, protein, catalytic activities, efficient catalytic capability, fungus Trichoderma sp. WL‐Go, aromatic pollutants degradation, 2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐nitroaniline, 3‐nitroaniline, azo dye decolourisation, Au     

Concentration dependence of lipopolymer self-diffusion in supported bilayer membranes

Self-diffusion coefficients of poly(ethylene glycol)2k-derivatized lipids (DSPE-PEG2k-CF) in glass-supported DOPC phospholipid bilayers are ascertained from quantitative fluorescence recovery after photobleaching (FRAP). We developed a first-order reaction–diffusion model to ascertain the bleaching constant, mobile fraction and lipopolymer self-diffusion coefficient D_s at concentrations in the range c ≈ 0.5–5 mol%. In contrast to control experiments with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (ammonium salt) (DOPE-NBD) in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), the lipopolymer self-diffusion coefficient decreases monotonically with increasing concentration, without a distinguishing mushroom-to-brush transition. Our data yield a correlation D_s = D₀/(1 + αc), where D₀ ≈ 3.36 µm² s⁻¹ and α ≈ 0.56 (with c expressed as a mole percent). Interpreting the dilute limit with the Scalettar–Abney–Owicki statistical mechanical theory for transmembrane proteins yields an effective disc radius a_e ≈ 2.41 nm. On the other hand, the Bussell–Koch–Hammer theory, which includes hydrodynamic interactions, yields a_e ≈ 2.92 nm. As expected, both measures are smaller than the Flory radius of the 2 kDa poly(ethylene glycol) (PEG) chains, R_F ≈ 3.83 nm, and significantly larger than the nominal radius of the phospholipid heads, a_l ≈ 0.46 nm. The diffusion coefficient at infinite dilution D₀ was interpreted using the Evans–Sackmann theory, furnishing an inter-leaflet frictional drag coefficient b_s ≈ 1.33 × 10⁸ N s m⁻³. Our results suggest that lipopolymer interactions are dominated by the excluded volume of the PEG-chain segments, with frictional drag dominated by the two-dimensional bilayer hydrodynamics.     

Quantitative correlation between geometric parameters and stress concentration of corrosion pits

Pitting corrosion damage often occurs in aluminum alloy structures and can significantly reduce the service life of structures and cause structural failures. In this research, three-dimensional corrosion pit morphology of 7075-T6 aluminum alloy was observed with the Sensofar PLμ confocal imaging profiler and scanning electron microscope. According to the corrosion pit morphology, we systematically investigated the quantitative correlation between the stress state and geometric features of a corrosion pit idealized as a semi-ellipsoidal pit. It is found that the stress concentration factor (SCF) increases with R_s (the ratio of pit width to length) and R_d (the ratio of pit depth to half-length). The maximum possible SCF is independent of R_d and increases linearly with R_s. The SCF of a rotated pit increases with the orientation angle in a cos²θ relation when R_s < 1.0. The empirical equations are also proposed to correlate the SCF to R_s, R_d and θ.