 Many atmospheric chemicals occur in the gas phase as well as in liquid cloud droplets and aerosol particles Therefore, it is necessary to understand the distribution between the phases According to Henry's law, the equilibrium ratio between the abundances in the gas phase and in the aqueous phase is constant for a dilute solution Henry's law constants of trace gases of potential importance in environmental chemistry have been collected and converted into a uniform format The compilation contains 17 350 values of Henry's law constants for 4632 species, collected from 689 references It is also available at http://wwwhenrys-laworg 

/pdf/compilation-of-henry-s-law-constants-version-4-0-for-water-58il9q0ogv.pdf

Compilation of Henry's law constants (version 4.0) for water as solvent

(b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

The Quantum Theory of Light

On-line monitoring of volatile organic compounds at pptv levels by means of proton-transfer-reaction mass spectrometry (PTR-MS) medical applications, food control and environmental research

Large polycyclic aromatic hydrocarbon (PAH) molecules carry the infrared (IR) emission features that dominate the spectra of most galactic and extragalactic sources. This review surveys the observed mid-IR characteristics of these emission features and summarizes laboratory and theoretical studies of the spectral characteristics of PAHs and the derived intrinsic properties of emitting interstellar PAHs. Dedicated experimental studies have provided critical input for detailed astronomical models that probe the origin and evolution of interstellar PAHs and their role in the universe. The physics and chemistry of PAHs are discussed, emphasizing the contribution of these species to the photoelectric heating and the ionization balance of the interstellar gas and to the formation of small hydrocarbon radicals and carbon chains. Together, these studies demonstrate that PAHs are abundant, ubiquitous, and a dominant force in the interstellar medium of galaxies.

Interstellar Polycyclic Aromatic Hydrocarbon Molecules

. Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially true for non-methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measurements made in smoke that has cooled to ambient temperature, but not yet undergone significant photochemical processing. All EFs are converted to one standard form (g compound emitted per kg dry biomass burned) using the carbon mass balance method and they are categorized into 14 fuel or vegetation types. Biomass burning terminology is defined to promote consistency. We compile a large number of measurements of biomass consumption per unit area for important fire types and summarize several recent estimates of global biomass consumption by the major types of biomass burning. Post emission processes are discussed to provide a context for the emission factor concept within overall atmospheric chemistry and also highlight the potential for rapid changes relative to the scale of some models or remote sensing products. Recent work shows that individual biomass fires emit significantly more gas-phase NMOC than previously thought and that including additional NMOC can improve photochemical model performance. A detailed global estimate suggests that BB emits at least 400 Tg yr−1 of gas-phase NMOC, which is almost 3 times larger than most previous estimates. Selected recent results (e.g. measurements of HONO and the BB tracers HCN and CH3CN) are highlighted and key areas requiring future research are briefly discussed.

/pdf/emission-factors-for-open-and-domestic-biomass-burning-for-20tklb2vkv.pdf

Emission factors for open and domestic biomass burning for use in atmospheric models

Untersuchungen der thermischen Ausheilung von Uranspaltspuren in Apatitproben aus Durango (Mexiko) bei verschiedenen Temperaturen (381, 331, 285, 230 und 208°C) und fur Ausheizzeiten bis zu 12 Monaten erbrachten folgende Ergebnisse:

1.

Unabhangig von der Temperatur und Ausheizdauer besteht zwischen der Verkurzung der Spurenlangel und der Abnahme der Spurendichtep ein linearer Zusammenhang.




2.

Bei einer festen Temperatur last sich der zeitliche Verlauf der Spurenausheilung darstellen durch die Beziehung.

$$p(t) = p(o) \cdot \exp [ - \alpha (T) \cdot t].$$






3.

Mit den Meswerten des Ausheilkoeffizienten α(T) sind im Arrhenius-Diagramm (In α vs. 1/T) zwei Geraden mit verschiedener Steigung festgelegt. Es wird der Nachweis erbracht, das fur die quantitative Beschreibung der Spurenausheilung im geologisch auswertbaren Temperaturbereich von 0–240°C nur ein einziger Wert der Aktivierungsenergie masgebend ist.

Thermische Ausheilung von Uran-Spaltspuren in Apatiten, Alterskorrekturen und Beiträge zur Geothermochronologie

Investigation of fundamental physical properties of a polydimethylsiloxane (PDMS) membrane using a proton transfer reaction mass spectrometer (PTRMS)

Electron impact ionization cross sections of molecules

Electron attachment to C60 at low energies

Electron attachment (EA) and dissociative electron attachment (DEA) to 5-chloro uracil (5-ClU) was studied in the gas phase using a crossed electron/molecule beams technique. Besides production of a parent anion via a zero energy resonance, ion yields of nine different negative ions were observed in the electron energy range from about 0 to 14 eV. In the electron energy range from about zero to 5 eV, the formation of a transient negative ion was induced by electron attachment to the π* resonances located at about 0.24, 1.5, and 3.6 eV leading subsequently by unimolecular decay to various negative fragment ions. Absolute partial cross sections for EA and DEA to 5-ClU were obtained from the measured ion yields using a simple calibrating method. The dominant negative ion observed in the present experiment was (C4H2N2O2)− (corresponding to 5-ClU minus HCl) with a mass to charge ratio of 110, followed by Cl− ion (mass to charge ratios 35 and 37), the partial cross sections being σ(0.23 eV)=5×10−18 m2 and σ(0.23 eV)=3×10−18 m2, respectively. The parent anion produced (5-ClU)− has only a cross section value of σ(0 eV)=3×10−20 m2. The energetic thresholds for the formation of particular negative ions from 5-ClU in the gas phase were calculated at the G2(MP2) level of theory and compared with the experimental results. On the basis of these calculations structure and relative stability of some of the fragment ions was predicted. In the case of the two most abundant ions, their formation was observed well below the calculated electron energy threshold. The formation of these negative ions below the thermodynamic threshold is explained in terms of the high vibrational energy of the 5-ClU prior to the EA process.

Tilmann D. Märk

Papers

Thermische Ausheilung von Uran-Spaltspuren in Apatiten, Alterskorrekturen und Beiträge zur Geothermochronologie

Investigation of fundamental physical properties of a polydimethylsiloxane (PDMS) membrane using a proton transfer reaction mass spectrometer (PTRMS)

Electron impact ionization cross sections of molecules

Electron attachment to C60 at low energies

Electron attachment to 5-chloro uracil