Showing papers in "Physica Scripta in 1971"
TL;DR: In this paper, the ESCA spectra of C6H6, C4H4S, C 4H5N and 4H4O have been studied using MgKα radiation, 1253.6 eV.
Abstract: The ESCA spectra of C6H6, C4H4S, C4H5N and C4H4O have been studied using MgKα radiation, 1253.6 eV. The study included both the core orbitals and the valence orbitals. The C1s chemical shifts have been compared with the shifts predicted by the potential model, using both CNDO and ab initio gross atomic charges. We have obtained the binding energies of the deeper lying valence orbitals which cannot be reached by ultraviolet radiation. Further, the valence orbital spectra have been analysed using line intensities predicted from the atomic population of the molecular orbitals.
149 citations
TL;DR: In this article, the spectrum of singly ionized neon emitted by a hollow-cathode discharge has been observed in the 11 000-300? range, and the derived term system has been fixed in relation to the ground term using improved values for the wavelengths of the resonance lines 2s22p52P1?,?-2s2p62S? at 460.7284 and 462.3908?.
Abstract: The spectrum of singly ionized neon emitted by a hollow-cathode discharge has been observed in the 11 000-300 ? range. Wavelengths have been determined for 1 250 Ne II lines of which about 950 are new. The extended wavelength observations have led to the finding of more than 220 new energy levels, which means that in all 301 Ne II levels, belonging to the configurations 2s22p5, 2s2p6, 2s22p43s-7s, 3p-5p, 3d-5d, 4f-9f, and 5g-7g are now known. The derived term system has been fixed in relation to the ground term using improved values for the wavelengths of the resonance lines 2s22p52P1?,?-2s2p62S? at 460.7284 and 462.3908 ?. The 3P2 ionization limit has been determined to be (330 388.6?0.3) cm-1 above the ground level. Accurate wavelengths, useful as reference wavelengths, have been calculated in the 2 000-1 000 ? and 460-300 ? regions.
123 citations
NATO1
TL;DR: In this paper, the high resolution He I photoelectron spectrum of the (a12t25)2T2 < - (a 12t26)1A1 transition in methane has been recorded and analyzed and a value has been obtained for the adiabataic ionization potential.
Abstract: The high resolution He I photoelectron spectrum of the (a12t25)2T2 < - (a12t26)1A1 transition in methane has been recorded and analyzed and a value has been obtained for the adiabataic ionization potential. The electron spectrum resulting from ionization of a t2 electron is a composite of at least three overlapping electronic bands which are separated by several tenths of an eV. These bands are the split components of the 2T2 electronic state of the CH4+ ion which is distorted by strong Jahn-Teller forces. The symmetry of the molecule in these three electronic states is believed to be, in order of increasing energy, D2d
119 citations
98 citations
TL;DR: In this article, the beam-foil technique was used to measure radiative decay times in Si II, Si III, and Si IV in the wavelength region 700-6 000?.
Abstract: We have measured radiative decay times in Si II, Si III, and Si IV in the wavelength region 700-6 000 ? using the beam-foil technique. The lifetimes and transition probabilities have been evaluated by alternative methods of curve-fitting and cascade analysis. These results are compared with theoretical transition probabilities, and values in other members of the isoelectronic sequences. A recently introduced cascade analysis technique is shown to extract reliable lifetimes from heavily cascaded decay curves which are unresolvable by normal curve-fitting techniques. It can also yield information on the relative populations of the excited levels produced in the foil interaction. The present estimates of silicon in astrophysical objects are not changed by our measurements of transition probabilities in Si II and Si III. The solar photospheric and coronal abundance estimates of silicon relative to hydrogen thus still differ by a factor of three. We have measured the transition probabilities of most of the silicon lines observed in the red-shifted quasar spectra.
78 citations
TL;DR: In this article, ESCA spectra from the energy bands and some core levels in the alloys were recorded and compared with spectra of the pure elements, including Ag.60Pd.40, Rh.71Pd, and Au.45Pd., were found to have 0.8 eV lower binding energy.
Abstract: The alloys Cu.60Pd.40, Rh.60Pd.40, Ag.71Pd.29 and Au.45Pd.55 have been studied with ESCA and soft X-ray spectroscopy. ESCA spectra from the energy bands and some core levels in the alloys were recorded and compared with spectra from the pure elements. X-ray emission bands have been recorded for the components of the alloys and compared with ESCA valence band spectra. Core electrons of copper in the alloy Cu.60Pd.40 were found to have 0.8 eV lower binding energy than in copper metal. The core levels of the other elements had either very small or nondetectable shifts. No differences between the spectra from f.c.c. and b.c.c. Cu.60Pd.40 were found.
69 citations
TL;DR: In this paper, a summary of the available experimental information about doubly-excited terms in the Li I isoelectronic sequence and some new classifications and lifetime measurements are discussed.
Abstract: We give a summary of the available experimental information about doubly-excited terms in the Li I isoelectronic sequence and discuss some new classifications and lifetime measurements. Some new classifications in Be I are also suggested and we give the results of lifetime measurements for some singly-excited levels in Li II, Be I, and Be II.
69 citations
TL;DR: In this article, the beam-foil spectra of phosphorus between 600 and 2 200 A and measured radiative lifetimes for 21 excited terms in P I-P V were studied.
Abstract: We have studied the beam-foil spectra of phosphorus between 600 and 2 200 A and measured radiative lifetimes for 21 excited terms in P I-P V. We discuss the merits of several methods for evaluating the decay constants and compare the results with theoretical transition probabilities as well as with recent experimental studies of oscillator strengths in the P I, Si I, Al I, Mg I, and Na I isoelectronic sequences.
66 citations
TL;DR: Using the ESCA method, the electron binding energies for the 3d and 3p3/2 levels in Se have been determined for a set of selenium compounds.
Abstract: Using the ESCA method the electron binding energies for the 3d and 3p3/2 levels in Se have been determined for a set of selenium compounds. Correlations between binding energy and charge on the selenium atom are given.
58 citations
TL;DR: In this article, the authors presented the lifetime of 41 excited terms in the spectra of Be I, Be II, B I, B II and B III, based on earlier measurements made at the Research Institute for Physics in Stockholm using beamfoil technique.
Abstract: Lifetimes of 41 excited terms in the spectra of Be I, Be II, B I, B II, B III, C I, C II and C III are presented. The values are based on earlier measurements made at the Research Institute for Physics in Stockholm using the beam-foil technique. The present results have been obtained through a more detailed analysis of the old decay curves.
56 citations
TL;DR: In this paper, anomalous optical absorption is observed in thin Ag films just above the bulk plasma frequency, interpreted as excitation of longitudinal plasmons, an effect which is normally neglected when discussing optical properties.
Abstract: Anomalous optical absorption is observed in thin Ag films just above the bulk plasma frequency. The result is interpreted as excitation of longitudinal plasmons, an effect which is normally neglected when discussing optical properties. The dispersion relation of the plasma wave is obtained from the data.
TL;DR: In this paper, the variation of elastic constants of MgO with temperature has been measured from 4.2 to 300 K, in units of 1010 N/m2, with a limiting value of θ 0 = 948 K for the Debye characteristic temperature.
Abstract: The variation of elastic constants of MgO with temperature has been measured from 4.2 to 300 K. The values of the elastic constants at 4.2 K, in units of 1010 N/m2, are C11 = 30.67, C12 = 9.371 and C44 = 15.76. This gives a limiting value of θ0 = 948 K for the Debye characteristic temperature
TL;DR: In this paper, the upper end-point region of the tritium β-spectrum has been investigated, aiming at improved information on neutrino mass, neutrinos degeneracy and on the ft-value of the β-decay, the latter being of interest for judging the applicacability of PCAC for obtaining the modification of the axial vector matrix element due to pion exchange.
Abstract: The present work forms part of a detailed investigation of the upper end-point region of the tritium β-spectrum, aiming at improved information on neutrino mass, neutrino degeneracy and on the ft-value of the tritium β-decay, the latter being of interest for judging the applicacability of PCAC for obtaining the modification of the axial-vector matrix element due to pion exchange. By the application of high-efficient β-spectroscopic methods a considerable improvement in basic accuracy of data has been achieved, making it necessary to inspect in a more detailed way than previously done how the interplay between a β-decaying nucleus and its atomic surrounding affects the observed β-spectrum. The β-decay of an atom leads to a distribution in atomic final states; the present work is essentially concerned with the various quantitative consequences of this circumstance for the case of the tritium decay. The distribution in atomic final states is found to imply a mean square energy spread as large as (27 eV)2 in the end-point energy of the spectrum from the tritium atom. This inherent spread in end-point energy is comparable in magnitude with the experimental resolution width now reached in the investigation of the tritium β-spectrum and has to be considered when interpreting the exprimental data with respect to limits on neutrino mass and neutrino degeneracy. The spread in end-point energy found will present a severe inherent difficulty in any effort to improve further the experimental information on these two entities. The distribution in atomic final states also affects the interpretation of the extrapolated end-point energy in terms of the H3-He3 nuclear mass difference and further is found to imply that the proper screening potential to be employed in the Fermi function differs by no less than 50% from the value conventionally assumed. An approximate treatment of the β-decay of the T-H molecule indicates that no drastic change in the atomic effects on the tritium spectrum should result when the tritium atom is not free but chemically bound in some more complex atomic surrounding. Some consequences of a minor residual ambiguity in the magnitude of the atomic effects in this case are commented on.
TL;DR: In this article, statistical methods were used to obtain improved spectroscopic constants for the A2+ and X2i states of the United States of America, and careful attention was paid to the?-doubling constants.
Abstract: By using statistical methods improved spectroscopic constants are obtained for the A2?+ and X2?i states of OH. In particular careful attention has been paid to the ?-doubling constants. The difficulty of choosing a formula to express all the energy levels is discussed and complete tables of term values are included. The term values are judged to be accurate to better than 0.1 cm-1.
TL;DR: Using the 204Hg(α,2n) reaction and the pulsed beam of the 225 cm cyclotron, the 12+ and 10+ states of the (i13/2)-2 configuration in 206Pb at the energies 4 027.2 and 3 957.6 keV, respectively, were determined in this paper.
Abstract: Using the 204Hg(α,2n) reaction and the pulsed beam of our 225 cm cyclotron, we have been able to localize the 12+ and 10+ states of the (i13/2)-2 configuration in 206Pb at the energies 4 027.2 and 3 957.6 keV, respectively. It has been possible to determine the partial E2 transition probability for the 12+ → 10+ transition and to derive an effective charge for the i13/2 neutron, which is 0.94±0.04. It is concluded that the quadrupole polarization charge for the i13/2 neutron is about 50% larger than for the h9/2 proton.
TL;DR: In this article, Svensson et al. analyzed the Mg I-like spectrum Ti XI using the line list of the titanium vacuum-spark spectrum in the region 50 to 425 A published by Svensson and Ekberg.
Abstract: The Mg I-like spectrum Ti XI has been analysed by using the line list of the titanium vacuum-spark spectrum in the region 50 to 425 A published by Svensson and Ekberg. At the same time the iso-electronic spectra of potassium, calcium and scandium have been checked and extended. The main new results concern the singlets, but the triplet systems have also been improved. Intersystem combinations have been found for Ca IX, and the singlet-triplet connection for the other element has been established by interpolation. The np- and nd-series are now extended to n=7 and the nf-series to n=6. However, series perturbations affect the determination of the ionization energies, which causes an uncertainty of 0.08% to 0.05%.
TL;DR: Theoretical calculations of relative X-ray emission energies and intensities were made with all-valence-electron molecular orbital methods on the following systems: SO42-, SO32-, SCN-, ClO4-, and ClO3-. The relative energies are, for all cases, in agreement with experiments while the calculated intensities depend heavily on the approximation scheme chosen.
Abstract: Theoretical calculations of relative X-ray emission energies and intensities were made with all-valence-electron molecular orbital methods on the following systems: SO42-, SO32-, SCN-, ClO4-, and ClO3-. The relative energies are, for all cases, in agreement with experiments while the calculated intensities depend heavily on the approximation scheme chosen. The results indicate that a feature in the ClO3- spectrum previously attributed to decay products may partly originate from a molecular level. For SCN- an intensity calculation based on the ab initio calculations by McLean and Yoshimine is also presented.
TL;DR: In this article, the beamfoil spectra of the different carbon ions C II to C V have been studied between 300 A and 1 300 A in the energy range 0.4 MeV-2 MeV.
Abstract: Beam-foil spectra of the different carbon ions C II to C V have been studied between 300 A and 1 300 A in the energy range 0.4 MeV-2 MeV. Eleven new lines have been identified. The mean lives of numerous excited levels of C II, C III, C IV and C V have been measured and are compared with other experimental and theoretical data.
TL;DR: In this article, the spectrum of Mg III has been thoroughly investigated in the wavelength range 720 to 6 600 A by using powerful spectrographs and the analysis has been greatly extended to configurations with higher n and l values and the following configurations are now complete: 2p53s, 4s, 5s, 3p, 4p, 3d, 4d, 5f, and 5g
Abstract: The spectrum of Mg III has been thoroughly investigated in the wavelength range 720 to 6 600 A by using powerful spectrographs. The earlier analysis has been checked and slightly revised. The analysis has been greatly extended to configurations with higher n and l values and the following configurations are now complete: 2p53s, 4s, 5s, 3p, 4p, 3d, 4d, 4f, 5f, and 5g. Accurate level values have been derived. The number of identified lines is 373. The ionization energies have been derived by applying the polarization formula to 4f, 5f and 5g giving for 2p52P1½ 646 402±5 cm-1. The 2p53s, 3p, and 3d configurations are best described in the LS coupling scheme, and 4s, 5s, 4p, 4f, 5f, and 5g in the J K scheme.
TL;DR: In this paper, a combined magnetic and electric interaction for cadmium in ferromagnetic gadolinium was studied and the magnetic hyperfine field at 15 K was determined to be - 327(8) kG and its temperature dependence was compared to the magnetization at nearest Gd atoms.
Abstract: Combined magnetic and electric interaction is studied for cadmium in ferromagnetic gadolinium. The magnetic hyperfine field at 15 K is determined to be - 327(8) kG and its temperature dependence is compared to the magnetization at nearest Gd atoms. The angle β which the magnetic hyperfine field forms with the main component of the electric field gradient tensor is found to vary smoothly with temperature from β ≈ 35° at 0 K to β = 0° at the Curie temperature (293 K).
TL;DR: In this article, the emission spectrum of RuC obtained in a King furnace has been photographed in a high resolution Eagle spectrograph between 6 000-8 700 A. 46 bands were detected in this region.
Abstract: The emission spectrum of RuC obtained in a King furnace has been photographed in a high resolution Eagle spectrograph between 6 000-8 700 A. 46 bands were detected in this region. From a vibrational analysis it seems most likely that they belong to 8 sub-systems. The final arrangement of these sub-systems into systems has not been successful. For the most intense sub-system with the 0-0 band situated at 7 224 A the following molecular constants in cm-1 were derived:
TL;DR: In this article, the atomic lifetime of the series 3snf3F perturbed by 3p3d3F in Al II and 2p21D in Be I by the beam-foil technique was measured.
Abstract: Atomic lifetimes have been measured for the series 3snf3F perturbed by 3p3d3F in Al II and for the series 2snd1D perturbed by 2p21D in Be I by the beam-foil technique. The experimental results are compared with theoretical data based upon configuration interaction calculations, and discrepancies are discussed.
TL;DR: In this article, photo-emission measurements from cesium-coated Cu, Au and Ni films were obtained for photon energies below 11.2 eV, and the results were discussed with reference to the calculated band structures with particular attention given to the interconduction band transitions in Cu around the L symmetry point.
Abstract: Photoemission measurements from cesium-coated Cu, Au and Ni films obtained for photon energies below 11.2 eV are reported. Spectra from clean noble metals were also measured at 21.2 eV photon energy. It has been possible to reduce the work function of Au and Ni below 2 eV without any appreciable distortion of the photoelectron energy distributions. The spectra from cesiated Cu and Au show several previously unresolved details. The results are discussed with reference to the calculated band structures with particular attention given to the interconduction band transitions in Cu around the L symmetry point.
TL;DR: In this article, it was found that the excitation functions within one level scheme have similar slopes, whereas differences exist between excitation function of different level schemes, and that the populations of Li Ia levels are proportional to the probability of getting neutral Li, whereas the He I, He II, Li Ib and Li IIa population functions differ from the charge state distribution curves.
Abstract: Beams of 4He+, 6Li+ and 7Li+ ions accelerated to energies between 10 keV and 75 keV have been sent through thin foils of beryllium, carbon, aluminium or gold, or into a helium gas target. The photon emission immediately after the foil has been measured in the wavelength range 200 nm to 600 nm. Excitation functions have been measured for 11 Li Ia spectral lines, 8 Li Ib lines and 10 Li IIa lines. It was found that the excitation functions within one level scheme have similar slopes, whereas differences exist between excitation functions of different level schemes. From the excitation functions relative population functions have been constructed and it is found that the populations of Li Ia levels are proportional to the probability of getting neutral Li, whereas the He I, He II, Li Ib and the Li IIa population functions differ from the charge state distribution curves. Comparisons between the population of corresponding levels in 6Li and 7Li indicate that the collision time is a more relevant parameter than the projectile energy. The statistical weights related to the orbital angular momentum and to the total spin of the electronic structure are found to influence the beam-foil interaction, whereas the statistical weight related to the nuclear spin is not apparent. The foil excitation is compared to single atomic collisions, and it is concluded that the beam-foil excitation is the result of a multi-collision atomic interaction. Sputtered excited atoms of beryllium and aluminium have been observed.
TL;DR: In this paper, the spectra of scandium (600-6 000 ) with the beam-foil method were studied and a few previously unreported Sc III transitions appeared, as well as several well-known Sc III multiplets.
Abstract: We have studied the spectra of scandium (600-6 000 ?) with the beam-foil method. In the v.u.v. a few previously unreported Sc III transitions appeared, as well as several well-known Sc III multiplets, whereas most lines in the air region were ascribed to earlier classified Sc I and Sc II transitions. We also measured the mean lifetimes of 20 excited Sc I-Sc III levels and generally found good agreement with previous theoretical calculations and emission measurements.
TL;DR: In this article, the E1Σ+−X1 Σ+ system attributed to the SiO molecule has been obtained in absorption in flash discharges through SiH4 containing traces of oxygen.
Abstract: The E1Σ+–X1Σ+ system attributed to the SiO molecule has been obtained in absorption in flash discharges through SiH4 containing traces of oxygen. The region from 1 650 A to 2 000 A has been studied. The fifteen deepest vibrational levels of the E state have been analysed. The following molecular constants have been derived: T0 = 52 578.31 cm-1 ω'e = 675.52 cm-1 ω'eχ'e = 4.204 cm-1 B'e = 0.54727 cm-1 r'e = 1.7399 A D'e = 1.43 × 10-6 cm-1
TL;DR: In this article, the level crossing method was applied to the first four levels (n = 5, 6, 7, and 8) of the np 2P3/2 series in the Rb I spectrum.
Abstract: For Rb87 the level crossing method was applied to the first four levels (n = 5, 6, 7, and 8) of the np 2P3/2 series in the Rb I spectrum. By using magnetic dipole interaction constants from corresponding zero field optical double resonance experiments, the electronic gJ factors of 5, 6, and 7p 2P3/2 were calculated from the level crossing data. For these levels the natural radiative lifetimes were determined from the half-widths of the level crossing signals. For 8p 2P3/2 the a factor was obtained assuming gJ = -1.336 (2). From the measured electric quadrupole interaction constants b, decreasing values of the nuclear quadrupole moment Q were obtained in 5, 6, 7, and 8p 2P3/2. When core polarization effects are taken into account, the different 2P3/2 levels yield consistent values for the quadrupole moment. We find gJ(5p 2P3/2) = -1.3362 (6) gJ(6p 2P3/2) = -1.3347 (10) τ (5p 2P3/2) = 25.8 (8) ns τ (6p 2P3/2) = 111 (3) ns b (5p 2P3/2) = 12.510 (57) MHz b (6p 2P3/2) = 3.947 (13) MHz Q(5p 2P3/2) = 0.131 barn Q(6p 2P3/2) = 0.133 barn gJ(7p 2P3/2) = -1.3359 (11) a(8p 2P3/2) = 6.747 (14) MHz τ (7p 2P3/2) = 233 (10) ns b (8p 2P3/2) = 0.933 (20) MHz b (7p 2P3/2) = 1.768 (8) MHz Q(8p 2P3/2) = 0.131 barn Q(7p 2P3/2) = 0.133 barn Considering possible sources of error in the evaluation of the quadrupole moment we obtain Q(Rb87) = +0.132 (9) barn.
TL;DR: The nucleus 21084Po has been studied in the 208Pb(?,2n?) reaction as mentioned in this paper, and new levels belonging to the (h9/2, f7/2) and (h 9/2, i13/2 ) configurations have been observed.
Abstract: The nucleus 21084Po has been studied in the 208Pb(?,2n?) reaction. New levels belonging to the (h9/2, f7/2) and (h9/2, i13/2) configurations have been observed. An isomeric state at 5 057.6 keV is also proposed. The state is most likely formed by coupling the (h9/2, i13/2)11- two-proton state to the first 5- state in 208Pb.
TL;DR: In this article, the wavelengths have been measured for 200 lines of N I in the long-wave region and 71 lines in the vacuum-ultraviolet region, and the limit 2s22p23P2 has been determined to 117 356.46±0.12 cm-1.
Abstract: The wavelengths have been measured for 200 lines of N I in the long-wave region and 71 lines in the vacuum-ultraviolet region. The latter have also been calculated from the recalculated system of energy levels. The designations 6s2P3/2, 4d4D5/2, 4P5/2, 3/2, 1/2, 2F5/2, and 5d4D5/2, 4P5/2, 1/2 have replaced the previous designations 6s2P1/2, 4d4P5/2, 2F5/2, 4P1/2, 3/2, 4D5/2, and 5d4P5/2, 4D5/2, 4P3/2, respectively. The new levels 6s2P1/2, 4p2D5/2, 3/2, 2P3/2, 1/2, 5p4D7/2, 5/2, 3/2, 1/2, 4P5/2, 3/2, 1/2, 4S3/2, 2P3/2, 1/2, 2S1/2, 4d4D7/2, 3/2, 1/2, 5d4F3/2, 4D7/2, 3/2, 1/2, 4P3/2, and 6d4F9/2, 7/2 have been established. The limit 2s22p23P2 has been determined to 117 356.46±0.12 cm-1.