 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

https://ftims.pg.edu.pl/documents/196503/306769/electronimpactionization.pdf

Electron impact ionization of 5- and 6-chlorouracil: appearance energies

Cation and anion formation is studied experimentally upon inelastic low energy electron interactions with 5-bromouridine (BrUrd) using a crossed electron/neutral beams set-up combined with a quadrupole mass spectrometer. The BrUrd molecule belongs to the class of radiosensitizers that increase the sensitivity of DNA (or RNA) to ionizing radiation. In the case of positive ion formation the ionization efficiency curves are measured near the threshold and the corresponding appearance energies are determined using a non-linear least square fitting procedure. The anion yields are investigated in the electron energy range from about 0 to 14 eV. From the comparison of the present results for negative and positive ions information concerning the underlying mechanism of radiosensitizers is deduced.

Positive and negative ion formation via slow electron collisions with 5-bromouridine

The 4.4 eV dissociative electron attachment peak in CO2 was reinvestigated paying particular attention to (i) its structure associated with vibrational excitation and to (ii) the temperature dependence of the onset. For this purpose we have used two specially designed crossed beams machines, one having a trochoidal electron analyzer (TEM) and one with a hemispherical electron analyzer (HEM) for the production of the highly monochromatized electron beams (with FWHM’s down to 5 and 50 meV, respectively). The present results confirm the earlier findings in (i) interpreting the dominant structures of the 4.4 eV peak as being due to vibrationally excited states of CO in the reaction CO2+e → O−+CO and (ii) assigning the much weaker and narrower structures to the intermediate CO
 2
 −
 . In the temperature range between 300 and 245 K almost no temperature dependence of the onset can be seen in the present study. In comparison to NO and CO where the onset is vertical the CO2 threshold behavior is less steep indicating that in the CO2 case a different type of transition must be responsible for the onset of the O− production. Besides DA to CO2 we have for comparison and calibration purposes investigated also DA to CO and NO.

Tilmann D. Märk

Papers

Electron impact ionization of 5- and 6-chlorouracil: appearance energies

Positive and negative ion formation via slow electron collisions with 5-bromouridine

Dissociative electron attachment to CO2

Bindungs- und ortsselektive Abspaltung von H-Atomen aus Nucleobasen, induziert durch Elektronen sehr niedriger Energie (<3 eV)†

Fragmentation of propanoic acid by subexcitation electrons