Inorganic Chemistry
in Thin Water Films on Surfaces

Reactions in thin water films on surfaces are increasingly recognized as being important in the atmosphere, particularly the boundary layer. 

A new experimental system combining UV-visible spectral detection and gas phase long path FTIR with attenuated total reflectance infrared spectroscopy (ATR-FTIR) to follow the surface film simultaneously has been constructed and tested, and is now being applied to study reactions in thin films.

 

Photo of cell to study gas and thin-film reactions simultaneously

Interpretation of the spectra of surface species is carried out by comparison to predictions using quantum chemical calculations.  AirUCI also collaborates with the Xantheas group at PNNL in this research area. 

Accurate calculations of the spectroscopy of simple species such as HNO₃, HNO₃-H₂O, HONO, NO₃--H₂O, and H₃O+ can in some cases be useful in the interpretation of atmospheric thin films; e.g., the ATR spectrum of NO₂ hydrolysis in water films and the effects of photolysis on thin film species.  For example, the photolysis of nitric acid is being studied and shows that generation of an oxygen atom and HONO can occur at wavelengths below 240 nm.

The process is pertinent to the stratosphere.  Related reactions in the troposphere are being investigated.