Adsorption of aromatic hydrocarbons and ozone at environmental aqueous surfaces.
Adsorption of environmentally important aromatic molecules on a water surface is studied by means of classical and ab initio molecular dynamics simulations and by reflection-absorption infrared spectroscopy. Both techniques show strong activity and orientational preference of these molecules at the surface. Benzene and naphthalene, which bind weakly to water surface with a significant contribution of dispersion interactions, prefer to lie flat on water but retain a large degree of orientational flexibility. Pyridine is more rigid at the surface. It is tilted with the nitrogen end having strong hydrogen bonding interactions with water molecules. The degree of adsorption and orientation of aromatic molecules on aqueous droplets has atmospheric implications for heterogeneous ozonolysis, for which the Langmuir-Hinshelwood kinetics mechanism is discussed. At higher coverages of aromatic molecules the incoming ozone almost does not come into contact with the underlying aqueous phase. This may rationalize the experimental insensitivity of the ozonolysis on the chemical nature of the substrate on which the aromatic molecules adsorb.
Vácha
Robert
R
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic.
Cwiklik
Lukasz
L
Rezác
Jan
J
Hobza
Pavel
P
Jungwirth
Pavel
P
Valsaraj
Kalliat
K
Bahr
Stephan
S
Kempter
Volker
V
D000327:Adsorption; D001554:Benzene / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D003198:Computer Simulation; D006838:Hydrocarbons / Q000737:chemistry*; D008958:Models, Molecular; D009281:Naphthalenes / Q000737:chemistry; D010126:Ozone / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D012984:Software; D013055:Spectrophotometry, Infrared / Q000379:methods; D014867:Water / Q000737:chemistry
D006838:Hydrocarbons; D009281:Naphthalenes; D011725:Pyridines; D014867:Water; C031721:naphthalene; D012834:Silver; D010126:Ozone; D001554:Benzene