Low-energy excited states of 3d transition metal ions in zinc selenide

The results of studying the impurity heat capacity of Zn_1?x M _xSe (M = Cr²⁺, Fe²⁺, Ni²⁺, Mn²⁺) solid solutions in the temperature range 1.8–20.0 K are presented. A heat-capacity method is described and applied for the measurement of the intracenter-transition energy in these systems. The role of the Jahn-Teller effect in the formation of low-energy excited states of 3d ions in ZnSe is discussed.     

The 3d photoabsorption of Tm3+

The four lines predicted theoretically in Tm³⁺ 3d photoabsorption are observed. By fitting the eigenvalues and the observed energies, new values of radial parameters are determined and it is shown that the configuration 3d⁹4f¹³ in Tm³⁺ is better described in j-j coupling.     

Theoretical determination of the potassium far-wing photoabsorption spectra

This theoretical work reports full quantum-mechanical analysis of the potassium far-wing photoabsorption spectra. The accuracy of the adopted K₂ potential-energy curves and transition dipole moments is established by computing the vibration-rotation levels and the radiative lifetimes of the excited molecular states and by determining the variation law with temperature of the diffusion coefficient of atomic K(4p) in a ground potassium gas. The pressure-broadening calculations revealed that the photoabsorption spectra have, in the temperature range 850-3000 K, a satellite structure characterized by the presence of three peaks around 718.7 nm in the blue wings and 1048.1 and 1100.8 nm in the red wings. This theoretical work could in particular point out the occurrence in the blue wing of a satellite originating from the bound-free B←X transitions near 731.5 nm. All these results agree quite well with the experimentally measured values.     

Quantum and thermal fluctuation effects on the photoabsorption spectra of clusters

A first principles approach for the calculation of photoabsorption cross sections of clusters and molecules is presented which includes both quantum and thermal fluctuations. The method relies on an ab initio path integral representation of the nuclear quantum motion in conjunction with time-dependent density-functional theory for electronic excitations. It is shown that quantum fluctuations of cold lithium clusters, such as Li8 below 50 K, affect significantly their photoabsorption spectra.     

The closed-orbit and the photoabsorption spectra of lithium atom in varying＇magnetic fields

Using a simple analytic formula from closed orbit theory, we have calculated the photoabsorption spectra of Li atom in different magnetic fields. Closed orbits in the corresponding classical system have also been obtained for B=5.96T.We demonstrate schematically that the closed orbits disappear gradually with the decrease of the magnitude of the magnetic field. This gives us a good method to control the closed orbits in the corresponding system by changing the magnetic field, and thus changing the peaks in the photoabaorption spectra. By comparing the photoabsorption spectra of Li atom with those of hydrogen case, we find the core-scattered effects play an important role in multi-electron Rydberg atoms.     

Parametric four-wave mixing in the 3d and 4d Rydberg states of NO

2 Σ⁺,H^′ 2Π^±(v^′=2), and 4dσ,πO²Σ⁺,O^′ 2Π^±(v^′=0) Rydberg states of NO molecules are described. The analyses of the two-photon excitation functions and infrared emission spectra revealed that only the ²Π^- component was involved in PFWM. This is in good accordance with the absence of amplified spontaneous emission (ASE) in the ²Σ⁺ and ²Π⁺ components due to their predissociative character. Results provide some support for the mechanism that the generation of the vacuum ultraviolet radiation was brought by PFWM in which ASE served as a third driving wave. Received: 6 January 1998     

KⅡ离子3p光吸收谱的MQDT分析

利用多通道量子数亏损理论对钾的一价离子的3p光吸收光谱进行了分析,计算并预言了80多个实验上未观察到的能级以及相应能级的朗德g因子,对于实验上未区分的能级做了重新的认定,预言了自电离区的3p5ns(1/2,1/2)n=17-21的能级,讨论了通道之间的干扰情况。     

Superfield form of discrete gauge states in ĉ = 1 2d supergravity

A general formula for the discrete states (NeveuSchwarz sector) in N = 1 2D super-Liouville theory is written down in the world-sheet supersymmetric form. We then derive a set of gauge states at the discrete momenta. These discrete gauge states are shown to carry the ω_∞ charges and serve as the symmetry parameters in the old covariant quantization of the theory.     

Role of excited nuclear states in photoabsorption shadowing at medium energies

The effect of intranuclear motion of nucleons on the photoabsorption shadowing due to the conversion of a γ-ray photon into a vector meson in nuclear matter is analyzed. It is shown within the method of time-correlation functions that, in comparison with the results of the standard approach, the correction to the total photoabsorption cross section due to the nuclear shadowing is determined by two additional factors: the Fermi motion of nucleons in a nucleus and nucleon recoil.     

Continuum states of modified Morse potential

Using a proper approximation scheme to the centrifugal term, we study any l-wave continuum states of the Schrdinger equation for the modified Morse potential. The normalised analytical radial wave functions are presented, and a corresponding calculation formula of phase shifts is derived. It is shown that the energy levels of the continuum states reduce to those of the bound states at the poles of the scattering amplitude. Some numerical results are calculated to show the accuracy of our results.     

Charge states of cobalt ions in nanostructured lithium cobaltite: X-ray absorption and photoelectron spectra

The charge states of ions in nanostructured lithium cobaltite prepared by severe plastic deformation under pressure have been determined using X-ray absorption spectroscopy and photoelectron spectroscopy, as well as calculations of the atomic multiplets with allowance for the charge transfer. It has been found that small deformations (pressures up to 5 GPa and angles of anvil rotation up to 30°) lead to the generation of lithium vacancies in the bulk of the nanostructured material and the formation of the Li₂O phase on the surface. The charge compensation occurs at the expense of holes in oxygen 2p states; the electronic configuration of cobalt ions is 3d ⁶ L, where L is a hole in oxygen 2p states. It has been shown that nanostructured lithium cobaltite belongs to the class of insulators with a negative charge transfer energy. An increase in the degree of deformation of lithium cobaltite (at a pressure up to 8 GPa) leads to the formation of Co²⁺ ions (with the electronic configuration 3d ⁷).     

Delayed onset of 4d photoemission relative to the giant 4d photoabsorption of La

For the giant 4d photoabsorption of La, both the total photoabsorption spectrum and the N_4.5-derived Auger emission intensity spectrum increase significantly above hν ? 112 eV, with spectral peaks at hν = 118 and 119 eV, respectively. However, the predominant 4d photoemission partial cross section shows a delayed onset of ～ 4 eV, with a peak at hν = 121 eV, while the 5s, 5p, and 5d partial cross sections all show a strong resonant enhancement at lower energies, with spectral peaks at hν = 116.6 eV. These results are compared with a recent many-body calculation for Ce. The photon energy dependence of the La 4d_{$\text{5}\text{2}$}/4d_{$\text{3}\text{2}$} photo-emission branching ratio is consistent with a “final-state model.”     

Delayed beam-foil spectra of 3 MeV Ar ions

The VUV spectrum of foil-excited argon ions has been observed with time delays of up to 20 ns after excitation in a search for the intercombination lines of Mg-, Al- and Si-like ions. In Ar⁶⁺ the intercombination line has been identified and its wavelength has been determined with a precision equal to that achieved in a recent tokamak experiment. In Ar⁵⁺ and Ar⁴⁺ the signal is expected to be lower by one order of magnitude because of the longer lifetimes. We discuss possible identifications of very weak lines with the transitions of interest.     

Spin-orbit coupling enhancement of 3d ions in metals

The interactions between localised 3d and itinerant electrons due to the Coulomb and exchange potential are shown to be responsible for the increase in magnitude of ionic spin-orbit coupling.     

Continuum effects in excited states of light hypernuclei

The spectra of the hypernuclei ⁶_ΛLi, ⁷_ΛLi and ⁹_ΛBe are calculated in the lambda particle - neutron hole basis using the Green's function method. The model includes the effects of the Λ continuum. As a result the Λ escape widths are calculated. for the various hypernuclear states. A comparison with the recently measured strangeness exchange (K⁻, π⁻) reaction results is made.