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.     

Energy Levels of Singly-Ionized Platinum

The analysis of Pt II is extended by using accurate wavelength measurements by Sansonetti et al. Forty-three new even and 104 new odd levels have been found. The Slater-Condon parametric method is used for the interpretation of the 5d⁹, 5d⁸6s, and 5d⁷6s² low even configurations and the 5d⁸(7s+6d) high even configurations with root mean square deviations smaller than 80 cm⁻¹. The importance of the 5d⁸–5d⁷6s core interaction in interpreting the even-parity levels is stressed.     

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.     

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.     

Energy Levels,Classified Lines,and Zeeman Effect of Neutral Thorium

A list of about 9500 classified lines of Th I in the range 2345–29 662 Å is given. Lines in the range 2345–9239 A were observed and measured at NBS. Zeeman effect data for 2281 lines are listed. Lists of 254 even and 322 odd levels including their g values are presented. Among them there are 72 new levels, which were not contained in earlier publications.     

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°.     

The First Spectrum of Manganese,Mn I

In 1894, two short series of threefold spectral terms were discovered in the arc spectrum of manganese, and in 1922 other regularities involving fivefold and sixfold terms were discovered by Catalán who coined the word “multiplet” for the group of related lines resulting from combinations of such complex terms. Multiplet analyses of complex spectra promptly led to the present formal quantum interpretation of all such phenomena, but comparable progress in the analysis of the Mn I spectrum was handicapped by the paucity of experimental data.New observations of about 2500 wavelengths and intensities plus 440 Zeeman patterns made available in 1948–49 have now been completely exploited to derive additional atomic energy levels and thereby explain more of the observed Mn I lines. The result is that a total of 42 even terms with 125 levels and 60 g-values have now been designated and allocated to electron configurations, and 94 odd terms with 266 levels, 164 g-values, plus 13 miscellaneous levels. These terms are distributed among four multiplicities (doublets, quartets, sextets, octets), and transitions between even and odd terms account for more than 2030 lines ranging in wavelength from 1785 Å to 17608 Å.     

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.     

One-to-One Highly Nonlinear Power Functions on GF(2n)

It is an important problem to determine all one-to-one power functions on GF(2ⁿ) possessing a maximal nonlinearity. Unfortunately the maximal nonlinearity is not known explicitly for even n. But there is a very reasonable conjecture for it. Assuming that this conjecture is actually true we give an overview about all known cases and add two new results for even n. We expect that now all one-to-one power functions with maximal nonlinearity are found, with exception of conjectures of Welch and Niho for odd n.     

Progress Toward Redetermining the Boltzmann Constant with a Fixed-Path-Length Cylindrical Resonator

A single, fixed-path-length cylindrical-cavity resonator was used to measure c ₀ = (307.825 2 ± 0.001 2) m · s^?1, the zero-density limit of the speed of sound in pure argon at the temperature of the triple point of water. Three even and three odd longitudinal modes were used in this measurement. Based on the ratio M/?? ₀ = (23.968 644 ± 0.000 033) g · mol^?1, determined from an impurity and isotopic analysis of the argon used in this measurement and the measured c ₀, the value k _B = 1.380 650 6 × 10^?23J · K^?1 was obtained for the Boltzmann constant. This value of k _B has a relative uncertainty u _r(k _B) = 7.9 × 10^?6 and is fractionally, (0.12 ± 8.1) × 10^?6 larger than the value recommended by CODATA in 2006. (The uncertainty is one standard uncertainty.) Several, comparatively large imperfections of our prototype cavity affect the even longitudinal modes more than the odd modes. The models for these imperfections are approximate, but they suggest that an improved cavity will significantly reduce the uncertainty of c ₀.     

Electron impact excitation cross sections of tungsten atom

An experimental study is made of excitation of tungsten atom by electron impact at the energy of exciting electrons of 50 eV. The values of total excitation cross sections for 40 energy levels of WI are determined. The largest cross section of 2.06 × 10^?16 cm² corresponds to the odd level of 43 975 cm^?1 with J = 2.     

Study on Ambient Air Quality of Megacity Delhi,India During Odd–Even Strategy

State Government of Delhi had adopted odd–even scheme on vehicles plying in megacity Delhi to understand and improve the air quality of Delhi. To understand the effect of odd–even scheme on the concentration of pollutants, we have analysed the concentrations of chemical constituents [organic carbon, elemental carbon, water soluble inorganic components, trace elements and stable carbon and nitrogen isotopic composition (δ¹³C_TC) and N (δ¹⁵N_TN)] of PM_2.5 and PM₁₀ along with mixing ratios of trace gases (NO _x , CO, SO₂ and NH₃) data collected at an urban site of megacity Delhi during first phase (Phase-I: winter 2016) and second phase (Phase-II: summer 2016). During the Phase-I of the scheme, mass concentrations of PM_2.5 and PM₁₀ were changed by ?13 and ?5%, respectively, whereas, concentrations of PM_2.5 and PM₁₀ were changed by +18 and +16%, respectively during the Phase-II as compared to before the implementation of the scheme. The analysis of chemical constituents of PM_2.5 and PM₁₀ reveals that the odd–even strategy marginally changed the concentrations (markers) of vehicular emission. During both the phases, mixing ratios of trace gases (NO _x , CO, SO₂ and NH₃) were reduced non-significantly during the odd–even scheme as compared to before the implementation of the scheme.     

An X-ray Fourier line shape analysis of hexagonal tellurium films vacuum-evaporated under normal incidence

Detailed X-ray line profile studies have been made of thin films of hexagonal tellurium (an elemental semiconductor) in the thickness range 600–55 000 Å deposited by the vacuum evaporation method with normal incidence of the vapour beam. The analysis shows a considerable size effect (about 155–326 Å) and appreciable microstrain (about2.98(?1.47)×10^?3) in these tellurium films, as well as a near-isotropy in the size and strain parameters. The domain sizes for the fault-affected reflections (H ? K = 3N ± 1, L₀ odd or even) indicate that the occurence of both intrinsic (α) and growth (β) stacking faults is negligible throughout the range considered here. A high density of dislocations (about 10¹¹ cm^?2) has been observed in this work. Tellurium films grown on glass substrates were found to cleave along the prismatic plane instead of the basal plane, indicating the presence of c axis texture. A line shift analysis showed that the intrinsic stresses as well as the lattice parameter changes are small. Post-deposition annelaing affects the dislocation density slightly whereas all other microstructural parameters (except stacking faults, orientation and the intrinsic stresses) are significantly influenced for films deposited on pre-heated substrates.     

Fundamental Building Blocks of Strongly Correlated Wave Functions

The calculation of realistic N-body wave functions for identical fermions is still an open problem in physics, chemistry, and materials science, even for N as small as two. A recently discovered fundamental algebraic structure of many-body Hilbert space allows an arbitrary many-fermion wave function to be written in terms of a finite number of antisymmetric functions called shapes. Shapes naturally generalize the single-Slater-determinant form for the ground state to more than one dimension. Their number is exactly N! ^d?1 in d dimensions. An efficient algorithm is described to generate all fermion shapes in spaces of odd dimension, which improves on a recently published general algorithm. The results are placed in the context of contemporary investigations of strongly correlated electrons.     

Pressure-Volume-Temperature Relations in Liquid and Solid Tritium

PVT relations in liquid and solid T₂ near the melting curve were measured over 20.5 K–22.1 K and 0 MPa–7 MPa (0 bar–70 bar) with a cell that used diaphragms for pressure and volume variation and measurement. Because of ortho-para self conversion, the melting pressure P_m and the liquid molar volume V_lm increased with time. The rates were consistent with a second order reaction similar to that for c the J = odd concentration: dc/dt = ?k₁c² + k₂c(1 ? c), where k₁ = 6−9×l0⁻²h⁻¹. By extrapolation, the ortho and para forms differed by ΔP_m~6 bar and ΔV_lm~0.5%. Measurements of the volume change on melting and the thermal expansion and compressibility for liquid T₂ were consistent with those for H₂ and D₂. Impurities such as H₂, HT, DT, and ³He were removed by a technique using an adsorption column of cold activated alumina. Corrections for ³He growth during an experiment were adequate except near the triple point.     

Some Vibrational-Rotational Bands of Deuterated Methanes

A parallel band at 2,200 cm⁻¹ and a perpendicular band at 2,780 cm⁻¹ of CH₃D have been observed under high resolution and analysed. The analysis of the perpendicular band revealed the presence of l-type doubling in the doubly degenerate excited state. From the analysis of the parallel band it is found that B₀= 3.880 cm⁻¹. A hybrid band of CD₃H has been observed near 2,600 cm⁻¹. Both active components, A and E are observed and analysed. The ground state B₀ value found from this analysis is in good agreement with previous determinations.     

Lifetime Measurements in 178Hf

Lifetimes of levels from K^π = 2⁺, K^π = 4⁺ and several K^π = 0⁺ bands have been measured in the ¹⁷⁸Hf nucleus using the GRID technique. Lifetimes of the 2⁺ and 3⁺ levels were measured within the K^π = 2⁺ γ band. A lower limit was established for the lifetime of the 4⁺ level of the K^π = 4⁺ band. The resulting upper limits for the absolute B(E2) values exclude collective transitions from the K^π = 4⁺ to the ground state band but not to the K^π= 2⁺ band. Level lifetimes were also measured for several states within three separate K^π= 0⁺ bands. Evidence is presented for a previously unobserved case of two excited K^π= 0⁺ bands being connected via collective E2 transitions.     

Experimental and Theoretical Study of Kinetics of Bulk Crystallization in Poly(Chlorotrifluoroethylene)

The rate of isothermal bulk crystallization of poly(chlorotrifluoroethylene), T_m=221° C, was measured from 170° to 200° C. The intrinsic bulk crystallization, which accurately followed an n = 2 law, was shown to be a result of the injection of primary nuclei sporadically in time, with one-dimensional growth of centers derived from these nuclei. The crystallites are exceedingly small. The one-dimensional growth process was isolated by nucleating specimens with seed crystals, and its temperature-dependence determined between 191° and 205° C. The seed crystal isotherms followed an n = 1 law. The temperature coefficients of the rate of nucleation and the rate of growth were both strongly negative.A theory of homogeneous nucleation that takes into account the segmental character of the polymer chains is developed in some detail. A cylindrical nucleus is assumed. In the temperature range near the melting point, region A, where the radius and length of the nucleus are unrestricted, the rate of nucleation is shown to be proportional to exp(−α/T³ΔT²). The nucleation rate is proportional to exp (−β/T²ΔT) in region B, which extends from somewhat below the melting point to considerably lower temperatures; the length of the nucleus has a constant value l₀ in this region, but the radius is unrestricted. (In the above expressions, α and β are constants). Finally, at sufficiently low temperatures, region C is entered. Under certain circumstances, the rate of nucleation in region C will be extremely rapid, and correspond to a “nucleative collapse” of the supercooled liquid state. A calculation of the one-dimensional growth rate shows that it is proportional to exp(−γ/T²ΔT) where β=γ.A careful analysis of the experimental data obtained between 170° and 200° C clearly showed that both the rate of nucleation and the rate of growth were proportional to exp(−β/T²ΔT), and not exp(−α/T³ΔT²). The primary nucleation event was thus of type B in this interval. A detailed analysis of the data is given, and surface free energies and the dimensions of the nuclei quoted. Quenching experiments, where the polymer was crystallized well below 170° C, gave a firm indication of the existence of region C.An experimental study was made of the extremely slow crystallization process that prevailed when the degree of crystallinity became high. The onset of this stage of the crystallization was interpreted as being the result of a massive degree of impingement. This interpretation is justified by the calculations of Lauritzen, who has given a theory of impingements that predicts a pseudoequilibrium degree of crystallinity.As indicated above, the growth process originating at homogeneous nuclei is not of a three-dimensional or spherulitic character in the region of study. Such stray spherulites as do appear in this region are shown to originate at heterogeneities. The possibility that the intrinsic growth process may become three-dimensional at crystallization temperatures sufficiently near T_m is discussed.     

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.     

Infrared Spectrum of the v2+ v6 Band of C13C12H6

The infrared spectrum of the v₂+v₆ band of C¹³C¹²H₆ has been analyzed and a value of B₀= 0.64865 ±0.00005 cm⁻¹ determined. When this value is combined with that found in recent work on isotopically normal ethane, a “r_s” value of 1.527±0.004 A for the carboncarbon bond distance is obtained. (Uncertainties are probable errors.)