Intrinsic states in atomic shell theory

The use of intrinsic states to resolve multiplicity difficulties in nuclear shell theory has been extended to the atomic case. If Slater determinantal product states are cast in the role of intrinsic states, it is often possible to produce final states that approximate to the physical states better than those determined by the group-theoretical procedures of Racah. The standard multiplicity separations for electrons of various azimuthal quantum numbersl can also be reproduced in many cases by a judicious choice of an intrinsic state. The usefulness of the method is limited principally by the fact that orthogonal intrinsic states do not necessarily yield orthogonal final states.     

Determination of ultra trace amounts of cobalt in fish by graphite furnace Zeeman effect atomic absorption spectrometry

A method is described for determining stable cobalt concentrations in fish flesh and bone using polarized Zeeman effect graphite furnace atomic absorption spectrometry (ZAAS). Cobalt analysis on freshwater fish flesh samples (10 g dry weight) required predigestion and wet-ashing at 70-80 degrees C. Cobalt is chelated with ammonium pyrrolidine dithiocarbamate (APDC) extracted with methyl isobutyl ketone (MIBK) and analysed by ZAAS. The mean cobalt content calculated from the standard additions method using three replicate fish flesh samples was 4.23 +/- 1.0 microgram Co. Kg-1 (dry weight). Analyses were also carried out on flesh and bone samples from similar sized fish, of the same species, taken from three area lakes.     

Observations on the reactivity of pentafluorophenyl sulfonate esters

Studies on displacement reactions of alkyl pentafluorophenyl (PFP) sulfonates with amines are consistent with a mechanism involving an elimination-addition pathway; comparisons between the reactivity of PFP-sulfonates with sulfonyl chlorides and PFP-sulfonates with PFP-esters are also presented.     

Collisional relaxation of the three vibrationally excited difluorobenzene isomers by collisions with CO2: effect of donor vibrational mode

Relaxation of highly vibrationally excited 1,2-, 1,3-, and 1,4-difluorobenzne (DFB) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot DFB (E' approximately 41,000 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Collisions between hot DFB isomers and CO2 result in large amounts of rotational and translational energy transfer from the hot donors to the bath. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these states. The amount of translational energy gained by CO2 during collisions was determined using Doppler spectroscopy to measure the width of the absorption line for each transition. The energy transfer probability distribution function, P(E,E'), for the large DeltaE tail was obtained by resorting the state-indexed energy transfer probabilities as a function of DeltaE. P(E,E') was fit to a biexponential function to determine the average energy transferred in a single DFB/CO2 collision and fit parameters describing the shape of P(E,E'). P(E,E') fit parameters for DFB/CO2 and the previously studied C6F6/CO2 system are compared to various donor molecular properties. A model based on Fermi's Golden Rule indicates that the shape of P(E,E') is primarily determined by the low-frequency out-of-plane donor vibrational modes. A fractional mode population analysis is performed, which suggests that for energy transfer from DFB and C6F6 to CO2 the two key donor vibrational modes from which energy leaks out of the donor into the bath are nu11 and nu16. These "gateway" modes are some of the same modes determined to be the most efficient energy transfer modes by quantum scattering studies of benzene/He collisions.     

Der Nachweis von Formaldehyd

Ohne Zusammenfassung