Concentration measurements and isotopic composition of airborne molybdenum collected in an urban environment

Here, we report the first measurements of the molybdenum (Mo) isotopic composition of aerosols collected on Teflon air filters. Mo concentrations and isotopic compositions were measured at selected locations in the city of Calgary, Canada, including a residence, the isotope laboratory at the University of Calgary, the University of Calgary weather station, and the City of Calgary Transit bus garage. Concentrations ranged from 0.07 ng/m³ in the laboratory to 19.0 ng/m³ in the bus garage. The concentrations of Mo in the air samples collected in the bus garage were the highest measured in this study. To date, there are no reported data for the Mo isotopic composition of airborne Mo. In this study, the δ^98/95Mo values measured for the different urban sampling sites and reported relative to SRM 3134, ranged from ?0.18 to +0.94 ‰. The results of this investigation suggest that measurements of Mo concentrations and isotopic compositions have the potential to trace anthropogenic emissions in an urban environment.     

Influence of pressure on the relative population of the two lowest vibrational levels of the C <Superscript>3</Superscript> Π<Subscript>u</Subscript> state of nitrogen for electron beam excitation

Continuous and pulsed 12 keV electron beams were used to excite nitrogen within a gas cell at pressures ranging from 10 to 1400 hPa. The pressure dependence of the ratio of photon fluxes for emission from vibrational levels v'=0 and 1 of the C ³Π _u state has been studied. The results confirm the presence of a collisional excitation mechanism populating v'=0, 1 in addition to electron impact excitation. Rate constants of (1.27 ±0.04)×10^-11 cm³s^-1 [ v'=0] and (2.68 ±0.08)×10^-11 cm³s^-1 [ v'=1] were measured for C ³Π _u quenching by ground state nitrogen. For electron beam conditions relative excitation efficiencies of 1:0.59:0.22 for vibrational levels 0, 1 and 2 were calculated. The recorded flux ratios are compared with the predictions given by a vibrational relaxation model.     

Application of dn/dc data for the determination of partial specific volumes of dissolved macromolecules. II. Partial specific volume of ovalbumin in aqueous solution

The theory of an interferometric method for determining partial specific volumes of macromolecules is briefly reviewed. The experimental technique developed in this laboratory is described. Detailed results are given on the partial specific volume of ovalbumin in aqueous solution and its dependence on pH and KCl concentration. The results are compared, as far as possible, with dilatometric results obtained in another laboratory. The contribution of a change in partial specific volume of the macromolecules and in the partial specific volume of the water associated with them to the results is analyzed, and the scope of a possible complication due to changes in molecular polarizability is pointed out.     

The far-infrared spectrum of tetrahydrothiophene: The bend/twist vibrations and associated barriers

The far-infrared spectrum of tetrahydrothiophene is reinvestigated with a resolution of 0.12 cm^?1 in the region of 50–350 cm^?1. In addition to the bend transitions (ν_b) below 120 cm^?1 reported previously, a number of sequences revealed by the improved resolution are observed for the first time and assigned to transitions of 2ν_b, of the twist (ν_t), and of difference combinations (ν_t - ν_b). Simple one-dimensional modeling of the twist sequence, which is derived from a self-consistent bend-twist energy level diagram, with a quadratic-quartic Hamiltonian suggests a barrier to planarity on the order of 4250 cm^?1. A two-dimensional potential function in the dimensionless coordinates is found to be V(q_b, q_t) = ?249.6q_b² + 4.48q_b⁴ ? 215.5q_t² + 2.73q_t⁴ + 7.00q_b²q_t².     

Mehrfachstreuung mittelschneller Elektronen in Folien

Zeitschrift für Physik A Hadrons and nuclei - Electrons with an initial energy of 100 keV have been shot through thin films of Ni, Ge, Ag and Au. The angular distribution of the plurally...