 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

Unimolecular decay of metastable CO3

Besides the usual single-monomer evaporation, the (C 3 H 8 ) n (C 3 H 7 + ) cluster ions produced by electron-impact ionization of neutral propane clusters have been observed to decay by an additional channel leading to evaporation of up to four C 3 H 8 monomers. It is shown that this additional fragmentation channel is initiated by a new decay mechanism, i.e., the isomerization of an n-propyl ion to a more stable sec-propyl ion within the cluster

Slow metastable decay process of (C3H7+)(C3H8)n cluster ions induced by isomerization of the propyl ion.

Electron impact ionization cross sections measured close to threshold are reported for the newly discovered greenhouse gas SF5CF3. No stable parent ion is detected but several cations are detected and their appearance energies?(AE) have been measured. The AE (CF3+/SF5CF3) = 12.87?0.10?eV is in excellent agreement with a recently reported value derived from a photoelectron-photoion coincidence experiment. Other ion thresholds are: AE (CF+/SF5CF3) = 24.44?0.10?eV, AE (CF2+/SF5CF3) = 17.80?0.50?eV; AE (SF+/SF5CF3) = 12.66?0.20?eV; AE (SF3+/SF5CF3) = 14.48?0.10?eV; AE (SF5+/SF5CF3) = 13.16?0.60?eV. Two thresholds are suggested for AE (SF4+/SF5CF3) = 16.10?0.30 and 12.10?0.30?eV. A tentative assignment of an AE for SF2+/SF5CF3 of 15.6?1.0 is also given. These results confirm that SF5CF3 is unlikely to be photolysed in the lower stratosphere and therefore will have a long lifetime against solar photodissociation.

Electron impact ionization studies for SF5CF3

Evaporation of c4 (c4+) from c60z+

Electron impact ionization involves the collision of an electron with a target particle and the subsequent production of an ion (and a neutral) and the respective ejected electron(s). A measure of the probability for this reaction is the total ionization cross section (see Chapter 7), i.e., the cross section for producing a single positive charge in the exit channel of the ionization reaction regardless of the details of the reaction products (mass to charge ratio, electronic states, neutral fragments etc.). Another (more detailed) measure is the partial ionization cross section, which describes the probability for an individual ionization process, including dissociative ionization, multiple ionization, and more generally, ionization to a particular final state of the produced ion.

Tilmann D. Märk

Papers

Unimolecular decay of metastable CO3

Slow metastable decay process of (C3H7+)(C3H8)n cluster ions induced by isomerization of the propyl ion.

Electron impact ionization studies for SF5CF3

Evaporation of c4 (c4+) from c60z+

Partial Ionization Cross Sections