atmospheric chemistry; snow; cryosphere; adsorption; uptake; trace gases; climate change; air quality
Bartels-Rausch Thorsten, Wren S N, Schreiber Sepp, Riche Fabienne, Schneebeli M., Ammann Markus (2013), Diffusion of volatile organics through porous snow: impact of surface adsorption and grain boundaries, in Atmospheric Chemistry and Physics
, 13(14), 6727-6739.
Krepelova Adela, Bartels-Rausch Thorsten, Brown Matthew A, Bluhm Hendrik, Ammann Markus (2012), Adsorption of Acetic Acid on Ice Studied by Ambient-Pressure XPS and Partial-Electron-Yield NEXAFS Spectroscopy at 230–240 K, in Journal of Physical Chemistry A
, 117(2), 401-409.
Bartels-Rausch T, Bergeron V, Cartwright JHE, Escribano R, Finney JL, Grothe H, Gutierrez PJ, Haapala J, Kuhs WF, Pettersson JBC, Price SD, Sainz-Diaz CI, Stokes DJ, Strazzulla G, Thomson ES, Trinks H, Uras-Aytemiz N (2012), Ice structures, patterns, and processes: A view across the icefields, in REVIEWS OF MODERN PHYSICS
, 84(2), 885-944.
McNeill V Faye, Grannas A M, Abbatt Jonathan P D, Ammann Markus, Ariya Parisa A, Bartels-Rausch Thorsten, Domine Florent, Donaldson D James, Guzman M I, Heger D, Kahan Tara F, Klán P, Masclin S, Toubin C, Voisin D (2012), Organics in environmental ices: sources, chemistry, and impacts, in Atmospheric Chemistry and Physics
, 12(20), 9653-9678.
Donaldson D James, Ammann Markus, Bartels-Rausch Thorsten, Pöschl Ulrich (2012), Standard States and Thermochemical Kinetics in Heterogeneous Atmospheric Chemistry, in The Journal of Physical Chemistry A
, 116(24), 6312-6316.
Ulrich T, Ammann M, Leutwyler S, Bartels-Rausch T (2012), The adsorption of peroxynitric acid on ice between 230 K and 253 K, in ATMOSPHERIC CHEMISTRY AND PHYSICS
, 12(4), 1833-1845.
Bartels-Rausch T, Ulrich T, Huthwelker T, Ammann M (2011), A novel synthesis of the N-13 labeled atmospheric trace gas peroxynitric acid, in RADIOCHIMICA ACTA
, 99(5), 285-292.
George Christian, D'Anna Barbara, Herrmann Hartmut, Weller Christian, Vaida Veronica, Donaldson D James, Bartels-Rausch Thorsten, Ammann Markus (2011), Emerging Areas in Atmospheric Photochemistry, in V. Faye McNeill and Parisa A. Ariya (ed.), Springer , Berlin Heidelberg, 1-54.
The interaction of nitrogen oxides with ice surfaces is of ongoing interest in the atmospheric science community. Uptake of HNO3 to cirrus clouds, for example, has been shown to be an important loss process in the upper troposphere. At the Earth’s surface it has been observed that the surface snow can act as source of HNO2 in some locations and at during certain times and as sink of HNO2 at other locations and times. This active role of the snow and of the ice phase in atmospheric chemistry is of importance, because the various nitrogen oxide species are interconvertible: The loss of one nitrogen oxide species, will affect the production of other species. As the nitrogen oxide chemistry is directly linked to the HOx and O3 budget, this might impact the oxidative capacity of the atmosphere. However, open questions remain as, for example, the interaction of most nitrogen oxides species with ice surfaces has not been so well characterized as has been done for HNO3 and HNO2 in the last decades. Among these species, HNO4 has recently been suggested to contribute significantly to the loss of nitrogen oxides from the gas phase through uptake to ice in the upper troposphere as well as in the Polar boundary layer. Yet, final conclusions on the importance of this loss pathway are currently not possible due to a lack of sufficient data describing the HNO4 ice interaction. More generally, the nature of the uptake process of acidic gases to ice surfaces is not fully understood. One open question concerns the origin of the long-term, diffusion-like uptake observed in laboratory experiments for some acidic gases. It has been suggested that this tailing is connected to the presence of grain boundaries, but experimental evidence is missing. As a significant fraction of an acidic gas can be taken up via this diffusive process, better knowledge of this process is of importance to describe the uptake of acidic gases to ice or snow in the environment. One approach to improve our understanding of the impact of ice morphology on the uptake process is to use ice samples where the number of individual ice grains is well characterized. A further aim should be to use single crystalline ice samples to exclude the diffusion into grain boundaries.Another aspect of interest is the role of dissociation of acids on the uptake process and the protonation equilibrium of acids on the ice surface. Even for well-characterized nitrogen oxides, such as HNO3, the fraction of dissociated acid upon adsorption still needs to be determined at temperatures relevant to the environment. Connected to this issue is the question of acidity of the ice surface and the nature of the protonation equilibrium at the ice surface. Molecular dynamics simulations and ab initio calculations point to a more acidic surface of water and ice compared to the bulk, while experiments with macroscopic resolution suggest a less acidic surface. This controversy can currently not be solved. More experiments on this issue are needed.In this project, we plan to study the interaction of HNO4 with ice surfaces. First, we will focus on the reversible adsorption using well-established methods such as a coated wall flow tube and a packed bed flow tube, both at atmospheric pressure. Full adsorption isotherms, i.e. the temperature and partial pressure dependence will be obtained. The packed bed flow tube experiments will already give indication of long-term, diffusion-like uptake, which will be analyzed using existing 2-D models. In these experiments, the uptake will mainly be derived by analysis of the gas phase. Additionally, irreversible uptake to the ice phase will be analyzed using ion chromatography. Next, we aim to perform uptake experiments on ice single crystals and well-defined polycrystalline ice. This set of experiments will rely on an existing method to analyse the number and size of individual ice grains in the sample. With this method we will also analyse the ice phase used in the coated wall flow tube and in the packed bed experiments described above. The uptake experiments on ice single crystals and well-defined polycrystalline ice will be performed in a Knudsen Cell so that also kinetic information on the uptake can be derived. The amount of adsorbed species with time will be monitored directly on the ice surface using radioactive labelled HNO4. Also the uptake of HNO3 and HNO2 will be briefly looked at for comparison reason. To investigate the protonation equilibrium of acids at the ice surface upon adsorption a new method will be developed based on laser induced fluorescence. The spectral changes of an pH sensitive, fluorescent dye will be used to derive the acidity of the ice surface and to observe the dissociation of acids upon adsorption. Sensitivity for the surface of the ice crystal will come from the amphiphilic properties of the fluorescent dye.