Weak-coupling State Research Articles

Pressure dependence of optical properties in halogen-bridged mixed-valence metal complexes

Some of the halogen-bridged mixed-valence metal complexes are studied under high pressure by the measurements of lattice parameters, Raman frequencies, optical gaps, luminescence peak and X-ray absorption near edge structure. All of them are consistently explained according to the theory on the quasi-one-dimensional electron-phonon system. As the Peierls gap decreases with pressure, the electron-phonon system is continuously changed from a moderate coupling state to a weak coupling state, not by decreasing the electron-phonon coupling energy, but by increasing the transfer energy.

Pressure Dependence of Absorption Edge, Luminescence Peak and Raman Frequency in Wolffram's Red Salt

Absorption, luminescence and Raman spectra are studied under high pressure in Wolffram's red salt. It is suggested that the quasi-one-dimensional electron-phonon system is continuously changed by pressure from a moderate coupling state at atmospheric pressure to a weak coupling state, not by decreasing the electron-phonon coupling energy, but by increasing the transfer energy. The decrease of the phonon energy of the symmetric stretching vibration of Cl around Pt IV and the rapid decrease of the energy gap with the pressure increase up to 0.2 GPa are thought because the Pt IV -Cl distance would increase with increasing pressure as the Pt IV -Pt II distance decreases.

Direct transfer and two-step processes in the 42Ca(α, 3He)43Ca reaction

Abstract The 42 Ca(α, 3 He) 43 Ca reaction has been studied at 36 MeV incident energy. Angular distributions have been measured from 4° to 42° using a split-pole spectrometer and position sensitive Si detectors, for about 40 levels located up to 6 MeV excitation energy. A local zero-range DWBA analysis has been carried out; l = 3 and 4 assignments are tentatively proposed for levels located above 4 MeV excitation energy, indicating a strong fragmentation of the 1 f 5 2 strength between 4 and 6 MeV and the location of the main component of the 1 g 9 2 strength above 6 MeV. A number of weakly excited levels cannot be reproduced by DWBA analysis. Their angular distributions have been compared with the results of coupled-reaction-channel calculations assuming two-step excitation of weak coupling states with a [ 42 Ca ∗ ⊗ f 7 2 structure. A reasonable agreement has been obtained, confirming that the two-step process cannot be neglected in the analysis of the (α, 3 he) reaction.

Single-particle and core-excited states in 49Sc : (II). The 48Ca(α, t) 49Sc reaction

The 48Ca(α, t) 49Sc reaction has been studied at 36 MeV incident energy. About eighty levels have been observed up to 7.5 MeV excitation energy and angular distributions were measured from 6° to 58°, using a split-pole spectrometer. A local zero-range DWBA analysis has been carried out, and the deduced l-assignments and spectroscopic factors are compared with those obtained from the ( 3He, d) reaction. In the other hand, a large number of angular distributions cannot be reproduced by the DWBA calculations; they have been compared with the results of coupled-reaction-channel calculations, assuming two-step excitation of weak coupling states with a [ 48 Ca ∗ ⊗ f 7 2 ] structure. Good agreement between experimental angular distributions and two-step predictions is obtained for several 49Sc levels, suggesting spin and parity assignments. Moreover, as rather large cross sections are predicted for two-step excitations, it is concluded that, generally, these processes cannot be neglected in the analysis of (α, t) reactions.

Weak coupling and high-spin states in 145Eu

High-spin states feeding the 11 2 − isomer in 145Eu have been studied using in-beam γ-ray spectroscopy. A new 5.5 ns ( 19 2 − ) isomeric state has also been identified. Most of the levels can be interpreted in simple weak coupling terms as either π d 5 2 −1 ⊗ 146 Gd or π g 7 2 −1 ⊗ 146 Gd or π h 11 2 ⊗ 144 Sm . The 5.5 ns isomer probably has a ( π d 5 2 −2π h 11 2 ) 19 2 − configuration.

Absence of proton weak coupling states in93Nb

The reactions93Nb(p, p)93Nb,93Nb(p, n)93Mo, and93Nb(p, p′) through isobaric analog resonances in94Mo have been used to study the structure of low-lying93Nb states, specifically the degree to which these states can be described as single protons coupled to the core states of92Zr. Excitation curves were obtained from 5.8 to 7.6 MeV incident proton energy, for eight states in93Nb. Results of this work are compared to results from Coulomb excitation studies,93Nb(n, n′γ),93Nb(d,p),92Zr(3He,d),94Mo(d,3He) and other related work.

The non-normal parity states of 209Bi and 207Pb

The low-lying non-normal parity states of 209Bi and 207Pb are studied by means of the shell model, assuming 1h-2p and 2h-1p configurations, respectively. The observed energy spectra are well reproduced. The wave functions obtained are analysed in comparison with those defined in the weak-coupling model and existence of the octupole multiplet and the mixing with other states are discussed in detail. The conditions for the existence of the weak-coupling states are also discussed.

Weak-coupling states in odd Zr isotopes

Weak-coupling states in 91, 93, 95Zr were investigated using the analog resonances technique. A consistent set of spectroscopic factors relative to those determined in a (d,p) experiment, was derived for a total of 24 states.

Octupole weak coupling states in 55Mn

The inelastic scattering of 17.5 MeV protons from 55Mn reveals a multiplet of states exhibiting the same angular distribution as is seen for the collective octupole state of 56Fe. The magnitudes of the cross section are in agreement with the predictions of the weak-coupling model.