The low-lying structures of the self-conjugate ( N = Z ) nuclei 8241Nb41 and 8643Tc43 have been investigated using isomeric-decay spectroscopy following the projectile fragmentation of a 107Ag beam. These represent the heaviest odd®Codd N = Z nuclei in which internal decays have been identified to date. The resulting level schemes shed light on the shape evolution along the N = Z line between the doubly-magic systems 5628Ni and 10050Sn and support a preference for T = 1 states in T z = 0 odd®Codd nuclei at low excitation energies associated with a T = 1 neutron®Cproton pairing gap. Comparison with Projected Shell Model calculations suggests that the decay in 82Nb may be interpreted as an isospin-changing K isomer.
A series of monodispersed oligo(p-phenyleneethynylene)s were synthesized bearing intramolecular hydrogen bonds between side chains of adjacent phenylene units in the backbone. Thus, all repeating units of the molecules are constrained in a coplanar orientation. Such planarized conformation is considered favorable for single-molecule conductance. Photophysical characterization results show narrowed bandgaps and extended conjugation lengths, consistent with a rigid, planar backbone framework as a result of intramolecular hydrogen bonding.
For the time being, Integrated Optics is able to produce a range of devices able of efficiently modulating phase, amplitude and frequency of guided waves in single mode structures implemented at the surface of active materials such as Lithium Niobate. In most of the cases, their basic principle relies on the interference pattern of two guided waves and the classical implementations of such modulators were mainly related to COBRA switch type directional couplers or to MACH ZEHNDER type interferometers. Only very recently a structure combining the coupled waveguides of a COBRA and the Y junction of the MACH ZEHNDER interferometer was designed. This paper is an analysis of the switching characteristics of this Y-fed directional coupler and of its high frequency modulation properties.
The yield of particle mass in secondary organic aerosol (SOA) formed by dark ozonolysis was measured for 0.3-22.8 ppbv of reacted alpha-pinene. Most experiments were conducted using a continuous- flow chamber, allowing nearly constant SOA concentration and chemical composition for several days. For comparison, some experiments were also conducted in batch mode. Reaction conditions were 25 degrees C, 40% RH, dry (NH4) SO4 seed particles, and excess 1-butanol. The organic particle loading was independently measured by an aerosol mass spectrometer and a scanning mobility particle sizer, and the two measurements agreed well. The observations showed that SOA formation occurred for even the lowest reacted alpha-pinene concentration of 0.3 ppbv. The particle mass yield was 0.09 at 0.15 mu gm(-3), increasing to 0.27 at 40 mu gm(-3). Compared to some results reported in the literature, the yields were 80 to 100% larger for loadings above 2 mu gm(-3). At lower loadings, the yields had an offset of approximately + 0.07 from those reported in the literature. To as low as 0.15 mu g m(-3), the yield curve had no inflection point toward null yield, implying the formation of one or several products having vapor pressures below this value. These observations of increased yields, especially for low loadings, are potentially important for accurate prediction by chemical transport models of organic particle concentrations in the ambient atmosphere.