Investigation of states in 30P via the 30Si(3He,t)30P reaction at 30 MeV

The ³⁰Si(³⁰He, t)³⁰P reaction has been measured for about 100 levels in ³⁰P with E_x < 8.8 MeV. Little selectivity in the population of states has been observed. For 75 levels angular distributions have been analysed using a “fingerprint method” by determining the L-value from a comparison in shape with transitions to states with known J^π. For possible mixed L-transitions a dominance of the higher L-value is observed for almost all cases. Coulomb displacement energy calculations utilizing shell-model wave functions have been used to identify T = 1 states.     

The structure of 32S I. Spectroscopy of highly-excited states

Assignments of I, π, T are made to 30 levels in ³²S between 7.35 and 11.76 MeV excitation energy, making the spectroscopy of the T= 0 states rather complete up to 10 MeV and that of the T = 1 states up to 12 MeV. A reassessment of existing data in the light of the new results clarifies the spectrum of I ^π = 1⁺, T = 1 states up to 15 MeV excitation energy. High-spin states (I = 52 - 7) below 10 MeV excitation energy have been investigated by n t γ angular-correlation measurements with the ²⁹Si(α, nγ) reaction at E _α 14.4 MeV. Five g-wave resonances of the ³¹P(p, γ) reaction, leading to the formation of I _π + 4⁺, 5⁺ states in ³²S, have been identified between 10 and 12 MeV excitation energy. The spectrum of T = 1 states between 10.7 and 12 MeV, has been investigated by measurements of γ-ray angular distributions on resonances of the ³¹P(p, γ) reaction and by measurements of resonance strengths. Several ³²S levels between 7.35 and 8.75 MeV excitation energy were studied as final states in resonance decays. Finally a search was performed for I ^π = 0⁺ resonances of the ²⁸Si(α, γ) reaction.     

Microscopic calculations for the 8Li system

A microscopic multi-channel cluster model calculation for the ⁸Li scattering system has been performed. Diagonal phase shifts, channel coupling strengths, and eigenphases are presented. For comparison, the ⁸Li bound and quasibound states have been investigated by a refined resonating group calculation. The results of both types of calculations are in excellent agreement. In the energy region up to the ⁵He-t threshold the calculated S-matrix elements, the energy eigenvalues, and the overlaps of the normalized functions with the eigenvectors explain the origin of the experimentally detected levels and moreover give predictions for the existence of additional levels.     

Single-particle and core-excited states in 49Sc: (I). The 48Ca(3He,d)49Sc reaction

The ⁴⁸Ca(³He, d)⁴⁹Sc reaction has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 40° using a split-pole spectrometer, for about 160 levels located up to 18 MeV excitation energy. A local zero-range DWBA analysis has been carried out, using Gamow functions as form factors in the case of unbound states; l-assignments and spectroscopic factors are obtained for a large number of levels, most of them previously unknown. The summed experimental spectroscopic strengths for the T_<, l = 1 and l = 3 levels are in good agreement with the shell-model sum-rule limits for 1f-2p proton states, and their energy centroids have been determined. The $\text{lg}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ strength in ⁴⁹Sc is strongly fragmented: about 27% of the T_< strength is carried by twenty-three levels located between 6.5 and 13.5 MeV. Spectroscopic factors for analog states are compared with those from previous (p, p), (³He, dp) and (d, p) experiments.     

Multireference CI calculations of radiative transition probabilities between low lying quartet states of the C2+ ion

Potential energy functions for the ten lowest electronic states of the C₂⁺ ion have been calculated from correlated CASSCF and MC-CI electronic wavefunctions and used for derivation of the spectroscopic constants. The predicted values are expected to be accurate within 0.01 Å for R_e, 20–30 cm⁻¹ for ω_e and 0.05–0.1 eV for T_e. For the three lowest quartet states the electronic transition moment functions have also been calculated. For the transitions among these states, radiative lifetimes and absorption oscillator strengths are given which should be accurate within about 15%.     

Pressure shifts of 1D2 Rydberg states of Mg I

Pressure shifts of the 3snd ¹D₂ Rydberg states to n = 23 have been measured for He, A and Xe and found to agree with previous results for ²P states of alkalis. Improved term values for the energy levels from n = 13 to 23 have been obtained.     

The shell model and collective structures in54,55,56Fe

Extensive shell-model calculations have been performed on^54,55,56Fe. The results obtained in a model space with two and with up to threef _7/2 holes in the,⁵⁶Ni core are compared with experiment. The Surface Delta Interaction (SDI) and the Kuo Brown interaction (KB) have been used to calculate energy levels, spectroscopic factors and electromagnetic properties resulting especially for⁵⁶Fe in a remarkably good agreement with experiment. Admixtures of three-hole components in the wave functions are significant and increase with mass number. Properties of high-spin states withJ≦15 are discussed. Pronounced collective features derived microscopically are expected in⁵⁶Fe. Finally some suggestions for interesting experiments are given.     

Optical oscillator strengths for Be II and B III

A simple two-parameter analytic potential adjusted so as to produce the experimental energy levels is used to generate wave functions for the ground and excited states of the ions Be II and B III. Using these wave functions we calculate optical oscillator strengths for various excitations from the 1s ²2s(² S) ground state. The results are compared to experiment and other calculations.     

The centimeter and millimeter microwave spectra of butadiene sulfone and α,α′-D4 butadiene sulfone

Microwave measurements on the ground and first eight excited states of the ring-puckering vibration of butadiene sulfone have been extended to millimeter wavelengths. The microwave spectra of the same vibrational states of α,α′-D₄ butadiene sulfone have been observed. For both isotopomers the Coriolis interaction between the v = 0 and v = 1 states has been analyzed to give the energy separation between these two states. These data and the variation of the rotational constants have been used to derive reduced potential functions for the ring-puckering vibration. The barrier to ring inversion is 49(2) cm⁻¹ for butadiene sulfone and 44(2) cm⁻¹ for the α,α′-D₄ isotopomer. The ring-puckering vibrational dependence of the quartic centrifugal distortion constants, including a small dependence of Δ_J and δ_J, has been accounted for.     

The (t, α) reaction on 121Sb and 123Sb

Angular distributions of α-particles from the (t, α) reaction on ¹²¹Sb and ¹²³Sb have been measured for incident tritons of 12 MeV. Levels up to excitation energies of 5.2 and 4.9 MeV in ¹²⁰Sn and ¹²²Sn, respectively, have been identified and analysed by the DWBA. Values of orbital angular momenta of the transferred protons have been assigned and spectroscopic factors deduced for all strongly excited levels. The extracted ground-state wave functions of the target nuclei have been compared with the calculated ones. A mixture of collective degrees of freedom is present in the low-lying states, weakly excited by the above very selective proton pick-up reaction. These states are populated by the pick-up of external protons (outer shells). At higher excitation energy (between 4 and 5 MeV) there are many strongly excited states populated by the proton pick-up from the Z = 50 proton core (inner shells); a predominantly 1p-1h character has been assigned to these states.     

Low-lying states in112In

Low-lying states below 500 keV excitation in¹¹²In have been investigated via the¹¹²Cd(p, nγ) reaction. New levels have been established atE ^x=206.5keV and 456.1 keV from the measuredγ-ray excitation functions,γ?γ coincidences and the precision measurements of the (p, n) threshold energy of the ground state and of the 206.5 keV state of¹¹²In. Spins and parities of the 206.5 keV state (2⁺) and the 456.1 keV state (3⁺) and multipolarities and mixing ratios of the deexcitationγ-rays have been determined from the angular distributions and linear polarizations of the deexcitation γ-rays as well as the excitation functions of the residual levels. Possible configurations of the newly-found levels are discussed. Half-lives of two states have been remeasured:T _1/2=15.2±0.1 min for the ground state andT _1/2=20.9±0.1 min for the 156.4 keV (4⁺) state. The ground stateQ-value for the¹¹²Cd(p, n)¹¹² In reaction has been measured to be ?3.376±0.006 MeV.     

Cluster calculation of electronic structure and hyperfine interactions for α-Fe2O3

The MSX_α cluster technique has been used to study the electronic structure of hematite α-Fe₂O₃, where iron is formally in a 3d₅⁶S state. The calculated energy levels are compared with X-ray emission and photoelectron spectra. The wave functions have been used to compute the charge distribution, as well as hyperfine parameters such as quadrupole coupling constant, isomer shift and magnetic hyperfine field. The results indicate a considerable influence of chemical bonding on these parameters due to charge transfer and covalency. From the calculated field gradient and the measured quadrupole coupling constant a nuclear quadrupole moment for ^57mTe of about 0.11b is deduced. This value is smaller than the most recent estimates of 0.15b based on the ionic model but not as small as the value of 0.082b obtained from first principles calculations on iron dihalides.     

The properties of 116in excited states

Gamma and conversion electron spectra from the ¹¹⁵In(n, γ)¹¹⁶In reaction in the energy range 20–700 keV and 20–850 keV respectively have been measured with bent crystal and magnetic spectrometers. Gamma-gamma coincidences in the energy range 50–500 keV have been investigated with Ge(Li)-Ge(Li) arrangement. Proton spectra from the 12 MeV deuteron-induced (d, p) reaction taken at the University of Pittsburgh Tandem Van de Graaf accelerator were reanalysed. The ¹¹⁶In level scheme consisting of 56 levels in the energy range 0–1.4 MeV has been constructed. Parity is determined for all the levels introduced. Unique spin values are assigned to 37 levels. The information obtained was used to place limits to the J-values for the rest of the levels. The main components of the wave function are established for 23 levels, considered to be components of p-n multiplets in which the proton hole and odd neutron are in in one of the Z = 28 → 50 and N = 50 → 82 shell states, respectively. Energy splittings of p-n configurations by residual interactions taken as a combination of short range Wigner and singlet forces have been calculated. It is noted that many excited states cannot be described in the framework of two-quasiparticle configurations.     

Tentative level diagram of146Pm below 1.1 MeV

The level scheme of the doubly odd nucleus¹⁴⁶Pm was investigated by means of in-beam spectroscopy. The¹⁴⁶Nd(p, n) reaction in the 3.5–8 MeV proton energy interval on enriched targets has been used to populate the exited states of¹⁴⁶Pm. High resolutionγ-ray spectra using Ge(Li) and hyperpure Ge detectors and conversion electrons with a mini-orange spectrometer were measured. Withγ-exitation functions andnγ-coincidences usingnγ-discriminated NE231 neutron detectors transitions in¹⁴⁶Pm were identified,γγ-coincidences gave information aboutγ-cascades. With these data a level scheme of 38 levels below 1.1 MeV exitation energy has been deduced including 73 transitions. For 12 transitions experimental conversion coefficients have been evaluated, which agree with the expected values forM1/E2-transitions.     

Detailed study of the cluster structure of light nuclei in a three-body model: (II). The spectrum of low-lying states of nuclei with A = 6

The three-body α + 2N model developed in our earlier works to describe the ground states of the A = 6 nuclei is generalized here to describe the spectrum of the low-lying states of these nuclei. The levels of the nuclei are shown to be differently sensitive to the various Nα interaction components, whence some conclusions concerning the true form of the Nα interaction are drawn. The geometric structure of the ⁶Li and ⁶He ground states is studied in detail. A significant contribution of the stretched cigar-shaped three-particle configuration NαN with an α-particle between two nucleons has been found. The wave functions of the ground and excited states of the A = 6 nuclei are tabulated. The wave functions found have been tested carefully using numerous experimental data.     

Photoemission studies of single crystals of titanium carbide

The electron distribution in the valence band from single crystals of titanium carbide has been studied by photoelectron spectroscopy with photon energies h?ω = 16.8, 21.2, 40.8 and 1486.6 eV. The most conspicious feature of the electron distribution curves for TiC is a hybridization between the titanium 3d and carbon 2p states at ca. 3–4-eV binding energy, and a single carbon 2s band at ca. 10 eV. By taking into account the strong symmetry and energy dependence of the photoionization crosssections, as well as the surface sensitivity, we have identified strong emission from a carbon 2p band at ? 2.9-eV energy. Our results are compared with several recent energy band structure calculations and other experimental data. Results from pure titanium, which have been used for reference purposes, are also presented.The valence band from single crystals of titanium carbide have been studied by means of photoelectron spectroscopy, with photon energies ranging from 16.8 to 1486.6 eV.By taking into account effects such as the symmetry and energy dependence of the photoionization cross-sections and surface sensitivity, we have found the valence band of titanium carbide to consist of two peaks. The upper part of the valence band at 3–4 eV below the Fermi level consists of a hybridization between Ti 3d and C 2p states. The C 2p states observed in our spectra were mainly excited from a band about 2.9 eV below the Fermi level. The APW^5–9, MAPW¹⁰ and EPM¹¹ band structure calculations predict a flat band of p-character between the symmetry points X′₄ and K₃, most likely responsible for the majority of C 2p excitations observed. The C 2s states, on the other hand, form a single band centered around ?10.4 eV.The results obtained are consistent with several recent energy band structure calculations^{5–11, 13} that predict a combined bonding of covalent, ionic and metallic nature.     

Ab initio vibrational spectra and structure of the ground state of HeScH2+

Potential energy and dipole moment surfaces of the ¹A′ ground state of HeScH²⁺ have been calculated using both the internally contracted single and double excitation multireference configuration interaction and the coupled-cluster singles and doubles augmented by a perturbative treatment of triple excitations levels of theory. Analytical functions have been fitted to the discrete surfaces employing a multidimensional least squares approach. These analytical functions have subsequently been embedded within a rectilinear normal-coordinate vibrational Hamiltonian in order to calculate vibrational states and transition intensities for low-lying states of HeScH²⁺.     

Spectroscopy of highly excited states in29Si

Particleγ-ray coincidences have been measured in the²⁸Si (d,pγ) reaction at 6.5 and 7 MeV bombarding energy, in the²⁶Mg (α,nγ) reaction at 12, 14 and 15 MeV, and in the²⁷A1 (τ,pγ) reaction at 9 MeV. Theγ-decay has been observed for all bound states of²⁹Si and for 56 unbound states up to 12,960 KeV excitation energy. Particleγ-ray angular correlations were measured in the²⁸Si (d,pγ) reaction at 6.5 MeV and in the²⁶Mg (α,nγ) reaction at 12 MeV. Spin (-parity) assignments or restrictions were obtained for nearly all bound states and some high-spin states above the binding energy. The assignment of mirror levels in²⁹Si and²⁹P has been extended to 8.2 MeV excitation energy. The excitation energies of 41 positive-parity states are reproduced by shell model calculations. The possible existence of aK ^π=5/2⁺ band with prolate deformation is discussed.     

Measurements and calculations of self-broadening coefficients of lines belonging to the v2 band of H216O

The self-broadening coefficients of 150 lines belonging to the v₂ band of H₂¹⁶O between 1770 and 2250 cm^-1 have been measured using Fourier transform spectra (resolution ≈ 0.005 cm^-1). The four different methods which have been used to deduce the self-broadening coefficients from experiment are described in detail. The estimated average uncertainty is about 15% and varies from 7 to 30%, depending on the method used and on the line involved. Two theoretical calculations, one based on the Anderson-Tsao-Curnutte method and the other on the recent method proposed by Davies, have been performed, retaining only the dipole-dipole interaction. For some lines of the v₂ band and for some pure rotation lines, calculations based on other formalisms have also been performed. For all of these calculations, we have used accurate spectroscopic data: precise energy levels, realistic wavefunctions, and a complete dipole-moment operator expansion in order to compute the transition probabilities. As compared to the previously calculated values of the pioneering work of Benedict and Kaplan, where the Anderson-Tsao-Curnutte method was used, our calculations show improvements by about 14% in the agreement between measured and calculated self-broadening coefficients.