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The recombination O+O2+M→O3+M in the bath gases M=He, Ar, and N2 was studied over the temperature range 90–370 K and the pressure range 1–1000 bar. The temperature and pressure dependences of the reaction rates show an anomalous behavior which is attributed to superpositions of mechanisms involving energy transfer, complex formation and participation of weakly bound electronically excited O3 states. The results also show an analogy to oxygen isotope enhancements observed in ozone recombination and dissociation. Experiments in compressed liquid N2 were also made showing a transition to diffusion control. [ABSTRACT FROM AUTHOR]

The reaction Cl+O2+M[larger_closed_square]ClOO+M was studied by laser flash photolysis in the bath gases M=He, Ar, N2, and O2 over the temperature range 160–300 K and the pressure range 1–1000 bar. UV absorptions of ClOO were monitored, a maximum absorption cross section of σ(248 nm)=3.4×10-17 cm2 was determined. An expression for the equilibrium constant Kp =5.3×10-6 exp(+23.4 kJ mol-1/RT) bar-1 was derived between 180 and 300 K, which, by a third law analysis, yields ΔH○0 =-20.2±0,2 kJ mol-1. Limiting low pressure rate coefficients for Cl+O2 recombination of k0=[He]8.8×10-34(T/300 K)-3.0, k0=[O2]1.6×10-33(T/300 K)-2.9, k0=[N2]1.4×10-33(T/300 K)-3.9 cm6 s-1 were obtained over the range 160–260 K, as well as k0 (160 K)=[Ar]2.2×10-32 cm6 s-1. Rate constants for the reactions Cl+ClOO→Cl2+O2 or 2ClO, ClOO+ClOO→products, and ClOO+Cl2→Cl2O+ClO were also derived. The recombination Cl+O2(+M)→ClOO(+M) at pressures above 10 bar shows a transition to a high pressure plateau and, at pressures above 200 bar, to diffusion control. It is suggested that, like O+O2(+M)→O3(+M), the reaction is governed by a radical complex mechanism. [ABSTRACT FROM AUTHOR]

We analyze new-physics contributions to e+e−→ W+W− at the TeV energy scale, employing an effective field theory framework. A complete basis of next-to-leading-order operators in the standard-model effective Lagrangian is used, both for the nonlinear and the linear realization of the electroweak sector. The elimination of redundant operators via equations-of-motion constraints is discussed in detail. Polarized cross sections for e+e−→ W+W− (on-shell) are computed and the corrections to the standard-model results are given in an expansion for large $s/M^{2}_{W}$ . The dominant relative corrections grow with s and can be fully expressed in terms of modified gauge-fermion couplings. These corrections are interpreted in the context of the Goldstone-boson equivalence theorem. Explicit new-physics models are considered to illustrate the generation and the potential size of the coefficients in the effective Lagrangian. Brief comments are made on the production of W+W− pairs at the LHC. [ABSTRACT FROM AUTHOR]

The chemical cycling and spatio-temporal distribution of mercury in the troposphere is poorly understood. We measured gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (HgP ) along with CO, ozone, aerosols, 5 and meteorological variables at Storm Peak Laboratory at an elevation of 3200 ma.s.l., in Colorado, from 28 April to 1 July 2008. The mean mercury concentrations were 1.6 ngm-3 (GEM), 20 pgm-3 (RGM) and 9 pgm-3 (HgP ). We observed eight events of strongly enhanced atmospheric RGM levels with maximum concentrations up to 135 pgm-3. RGM enhancement events were unrelated to daytime/nighttime patterns and lasted for long time periods of 2 to 6 days. During seven of these events, RGM was inversely correlated to GEM (RGM/GEM regression slope ∼ -0.1), but did not exhibit correlations with ozone, carbon monoxide, or aerosol concentrations. Relative humidity was the dominant factor affecting RGM levels with high RGM levels always present whenever relative humidity was below 40 to 50%. We conclude that RGM enhancements observed at Storm Peak Laboratory were not induced by pollution events and were related to oxidation of tropospheric GEM, but the mechanism remain unclear. Based on backtrajectory analysis and a lack of mass balance between RGM and GEM, we propose that in situ production of RGM may have occurred in some distance allowing for scavenging and/or deposition of some RGM prior to reaching the laboratory, and that GEM oxidation is an important tropospheric Hg sink. Our observations provide evidence that the tropospheric pool of mercury is frequently enriched in divalent mercury and that high RGM levels are not limited to the upper troposphere. [ABSTRACT FROM AUTHOR]