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An ab initio study of the vertical electronic excitations in CX[SUB3]I, C[SUB6]X[SUB5]H, and C[SUB6]X[SUB5]I (X=H and F) is presented. All-electron basis sets are used and the relativistic effects are accounted for with the relativistic elimination of small components scheme. The structures are optimized with the complete active space self-consistent field approach and the excitation energies are computed with the spinorbit multiconfiguration quasidegenerate perturbation theory. The n-σ∗ transitions of CX[SUB3]I, low-lying π-π∗ transitions of C[SUB6]X[SUB5]H, and low-lying n-σ∗, π-π∗, and π-σ&lowasr; transitions of C[SUB6]X[SUB5]I are elucidated. For CH[SUB3]I, energy values of parallel and perpendicular transitions differ from experimental values by 455 and 1156 cm[SUP-1], respectively. Effects of fluorination are emphasized, it is found that fluorination increases the gap between [SUP3]Q[SUB0] and [SUP1]Q[SUB1] transitions and increase is substantially more in aryl iodides than in alkyl iodides. Electronic factors influencing increased I∗ quantum yield in the photodissociation on fluorination of alkyl iodides is attributed to increased gap between [SUP3]Q[SUB0] and [SUP1]Q[SUB1] transitions reducing curve crossing probability and for aryl iodides there is additional role by phenyl transitions. A correlation diagram illustrating transitions of aryl iodides is presented. [ABSTRACT FROM AUTHOR]

The spin-orbit coupling constants (A[sub v+]) for O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=0–17) and O[sub 2][sup +](a [sup 4]Π[sub u],v[sup +]=0–25) were computed based on the Pauli–Breit Hamiltonian with one and two electron terms for comparison with experimental measurements. In the present theoretical study, the vibrational wave functions are obtained using the potential energy curve calculated at the multireference configuration interaction (MRCI) level of theory, with single and double excitations from the complete active space self-consistent field (CASSCF) reference wave function. The electronic wave functions and spin-orbit coupling constants are obtained at the CASSCF and restricted MRCI levels. The effect on A[sub v+] for O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]) and O[sub 2][sup +](a [sup 4]Π[sub u],v[sup +]) due to interactions of the O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]), O[sub 2][sup +](a [sup 4]Π[sub u],v[sup +]), and O[sub 2][sup +]([sup 2]Σ[sub u][sup +]) states is examined. The theoretical A[sub v+] predictions for O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]) are found to be consistent with the experimental finding that O[sub 2][sup +](A [sup 2]Π[sub u]) is an inverted spin-orbit state at low v[sup +] levels and becomes a regular spin-orbit state at higher v[sup +] levels. Good accord between theoretical predictions and experimental results for O[sub 2][sup +](A [sup 2]Π[sub u],v[sup +]=0–12) is observed with discrepancies in the range of 2–10 cm-1. In the case of O[sub 2][sup +](a [sup 4]Π[sub u],v[sup +]), excellent agreement between theoretical ab initio and experimental results is found with a discrepancy of 2–5 cm-1. Our effort to theoretically reproduce experimental fine structure in the A[sub v+] curve for O[sub 2][sup +](a [sup 4]Π[sub u],v[sup +]) based on interstate vibrational interactions has met with limited success... [ABSTRACT FROM AUTHOR]

Discusses an experimental and theoretical study of the spin-orbit interaction for carbon dioxide and oxygen. Rotationally resolved pulsed field ionization photoelectron (PFI-PE); Angular momentum coupling factor for the photoionization of the present carbon dioxide system.

The high current cyclotron C-80 capable of producing 40-80 MeV proton beams with a current of up to 200 µA has been constructed at Petersburg Nuclear Physics Institute. One of the main goals of the C-80 is the production of a wide spectrum of medical radionuclides for diagnostics and therapy. The project development of the radioisotope complex RIC-80 (radioisotopes at the cyclotron C-80) at the beam of C-80 has been completed. The RIC-80 complex is briefly discussed in this paper. The combination of the mass-separator with the target-ion source device, available at one of the new target stations for on-line or semi on-line production of a high purity separated radioisotopes, is explored in greater detail. The results of target and ion source tests for a mass-separator method for the production of high purity radioisotopes82Sr and Ra223,224 are also presented. [ABSTRACT FROM AUTHOR]

A combined target-ion source unit (ionizing target) has been developed for the on-line production of radioactive single-charged ions. The target is able to withstand temperatures of up to 2500 °C and also acts as an ion source of surface, electron-beam, and laser ionizations. Using tantalum foil as a target material, the on-line combined target-ion source unit efficiency, which is the product of the ionization and release efficiencies, has been obtained for neutron-deficient isotopes of Eu, Gd, and Yb. These nuclides were ionized by the surface ionization inside a hot tungsten target container, holding tantalum foils as a target material. The results of the combined target-ion source unit use for on-line laser resonant ionization spectroscopy investigation of neutron-deficient Gd isotopes have been also presented. For neutron-rich isotopes produced from a high-density UC target, which were ionized by the surface ionization inside the target container, the ionization efficiency values have been obtained close to 100% for Rb and Cs and 10% for In. For Ag and Sn neutron-richisotopes, the values of the electron-beam ionization efficiency in the volume of the targetcontainer, correspondingly equal to 4% and 2%, have been obtained. [ABSTRACT FROM AUTHOR]

New laser installation for the resonance ionization spectroscopy in a laser ion source and for rare isotope production has been recently put into operation at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) facility (Petersburg Nuclear Physics Institute, Gatchina). This is a significant improvement of a previous target-laser ion source device of the IRIS mass-separator, working on-line with 1 GeV proton beam of PNPI (Petersburg Nuclear Physics Institute) synchrocyclotron. It makes possible for us to get the isobarically clean radioactive isotope beams of a great number of chemical elements. New laser setup provides the two- or three-resonance step ionization in the range of wavelength of 265-850 nm. The first results obtained at the laser setup for Tl isotopes are presented. [ABSTRACT FROM AUTHOR]

The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at the ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series of upgrade steps: replacement of the copper vapor lasers by a Nd:YAG laser; replacement of the old homemade dye lasers by new commercial dye lasers; installation of a complementary Ti:Sapphire laser system. The combined dye and Ti:Sapphire laser system with harmonics is capable of generating beams at any wavelength in the range of 210-950 nm. In total, isotopes of 31 different elements have been selectively laser-ionized and separated at ISOLDE, including recently developed beams of samarium, praseodymium, polonium, and astatine. [ABSTRACT FROM AUTHOR]

We report on structural and optical properties of green (λ∼520 nm) ZnCdSe/ZnMgSSe optically pumped laser heterostructures with a Zn(Mg)SSe/ZnSe graded-index superlattice (SL) waveguide, grown by molecular beam epitaxy. The pseudomorphic 400 nm thick waveguide comprising a set of strained ZnMgSSe/ZnSe and ZnSSe/ZnSe SLs of different periods and barrier-to-well thickness ratios at each side of a ZnCdSe quantum well (QW) active region provides efficient transport of nonequilibrium carriers to the QW. This results in reduction in laser threshold down to the extremely low value of 1.5 kW/cm2 at 300 K and increasing the external quantum efficiency above 44%. [ABSTRACT FROM AUTHOR]

Effect of an axial magnetic field influence on the ionization efficiency of surface and laser ion sources has been observed. The axial magnetic field applying in the range 500–800 G gives an increase of the ion current of atoms of all elements those are ionized in a hot cavity of the surface or laser ion source. Moreover, if for ionization of atoms with low ionization potentials such as K, Rb, and Cs the magnetic field applying effect is negligible, for elements with ionization potentials higher than 6 eV, such as Gd, Tm, Yb, Lu, and others it reaches value about 20 in the ion source temperature region of 2100–2500 °C. The results of on-line experiments are presented confirming the influence of the axial magnetic field on the ionization efficiency rise of neutron-deficient isotopes of rare-earth elements produced in the combined ion source-target assembly (ionizing target) and Eu isotopes resonantly ionized in the laser ion source and in the high temperature ionizing target. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A high temperature electron beam ion source (HTEBIS) for production of single charge ions of refractory elements was built and on-line used for production of isotopes of Fe, Co, Cu, Rh, and Pd. Off-line ionization efficiency measurement of pointed out elements have been carried out. The yields of some neutron rich isotopes of these elements, when HTEBIS was used with the uranium carbide target have been measured. The measured yields have been compared with calculated ones, obtained from experimentally defined cross-sections. A new designed and off-line tested version of HTEBIS with electron emitting cathode placed from the extraction electrode side has been discussed. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Different types of high temperature ion sources such as surface, laser, and electron beam ionization ion sources have been developed and tested in off-line and on-line experiments. All types of developed ion sources have an essential common feature: an existence of the ion confinement inside the ion source cavity. [ABSTRACT FROM AUTHOR]

In the framework of the research and development activities of the SPES project regarding the optimization of the radioactive beam production, a dedicated experimental study has been recently started in order to investigate the possibility of in-source ionization of germanium using a set of tunable dye lasers. Germanium is one of the beams to be accelerated by the SPES ISOL facility, which is under construction at Legnaro INFN Laboratories. The three-step, two color ionization schemes have been tested using a Ge hollow cathode lamp. The slow and the fast optogalvanic signals were detected and averaged by an oscilloscope as a proof of the laser ionization inside the lamp. As a result, several wavelength scans across the resonances of ionization schemes were collected with the fast optogalvanic signal. Some comparisons of ionization efficiency for different ionization schemes were made. Furthermore, saturation curves of the first excitation transitions have been obtained. This investigation method and the setup built in the laser laboratory of the SPES project can be applied for the photo-ionization scheme studies also for the other possible radioactive elements.