Electrothermal atomization with a metal micro-tube in atomic absorption spectrometry

The processes of atom formation and dissipation in a molybdenum micro-tube atomizer have been studied to obtain information on the reaction involved. Vapor temperature was found to be close to atomizer surface temperature. Appearance temperatures and activation energies were obtained for Al, Co, Cu, Mn, Pb, Sb, Se, Sn and Te in argon and argon-hydrogen atmospheres. The atom formation processes are divided into two groups : the reduction of the metal oxide followed by the atomization of free metal, and thermal dissociation of the metal oxide. Hydrogen significantly changes atom formation processes for some metals compared to those in pure argon. The dissipation process of atoms from the micro-tube atomizer appears to be purely gas-phase diffusional.     

The light-cone gauge at two loops: The scalar anomalous dimension

We demonstrate that the light-cone gauge is a feasible tool for multi-loop computations by using it to evaluate the two-loop scalar anomalous dimension, γ⁽²⁾, in a general gauge theory. In the special case of supersymmetry we obtain agreement with previous results which were derived using non-light-cone techniques.     

Classical and quantum mechanical aspects of time-dependent Hartree-Fock trajectories

In terms of a quantum mechanical representation based on Slater determinants, classical and quantum mechanical aspects of TDHF trajectories are investigated. The invariant integration measure of the determinantal representation is obtained in a general closed form. Phase space structures of the TDHF equation and its solutions are discussed on this basis. The formal classical structures provide a way of finding a semiclassical expression for the quantum mechanical propagator, into which the superposition principle among TDHF trajectories is incorporated. General properties of the semiclassical propagator such as the time translation/reversal symmetry, unitarity, etc., are studied. Two simple hamiltonian systems are employed as examples which exhibit analytical solutions for the propagator. To illustrate the effects of superposition of TDHF paths, a system of interacting two-level nuclei is numerically studied and a comparison with the exact result is made.     

Bonding and molecular motions in the 1:1 molecular complexes of 1,4-diazabicyclo[2.2.2]octane with tetrahalomethane as studied by means of NQR

NQR spectra were observed in the complexes of 1,4-diazabicyclo[2.2.2]octane (DABCO) with tetrachloromethane and tetrabromomethane at various temperatures. A phase transition was found at 319 K for DABCO·CBr₄. From spin-lattice relaxation times of nitrogen-14 in DABCO·CBr₄, the activation energy of the reorientation of DABCO about the NN axis was calculated to be 18.3 kJ/mol which agrees with the value obtained from the second moment of proton NMR spectra. The bond nature is discussed using the Townes-Dailey treatment.     

Polarized target asymmetry in π° photoproduction between 0.4 and 1.0 GeV around 100°

The polarized target asymmetry in the reaction γp→π°p has been measured at c.m. angles around 100° for photon energies between 0.4 and 1.0 GeV by detecting both the recoil proton and the π°. The result is compared with recent analyses.