Photolysis for the Environment

270-745-0114

E-mail: matthew.nee@wku.edu

Our group is interested in understanding the chemistry which effects the terrestrial, aquatic, and atmospheric components of our planet.  We use time and frequency resolved vibrational spectroscopy to monitor reactions as they happen, on time scales relevant to the early part of a series of complex reactions.

 

Photocatalytic degradation

Our third project involves developing Raman spectroscopy as a means of monitoring photocatalytic degradation of compounds, which is beginning to be implemented as a wastewater treatment plan in many districts. Our initial data indicate that we can see structural changes with ten times better time resolution using our methods than has been previously reported using chromatography experiments.

Photolysis reactions in aqueous solution and atmospheric chemistry

The connection between the ozone layer and the sun’s ultraviolet radiation (UV ‘light’)  is far more complicated than you might guess at first glance. Oxygen-oxygen bonds in Ozone (O₃) are broken upon exposure to UV light, but can also be broken by chemical attack from free radicals (like NO) also present in different concentrations throughout our atmosphere. Other compounds convert O₂ to ozone, replenishing the supply in the upper atmosphere, but also creating ozone near the surface of the earth, where it can be harmful to humans. Sometimes, the compounds that generate ozone are themselves generated as a result of a photochemical reaction, one in which light is a reactant. We can start this reaction in the lab with a laser pulse, and then monitor the products of this reaction as a function of the time after initial laser pulse by watching the IR or Raman spectrum change. By doing this, we learn about the earliest reaction rates and branching ratios, information which is critical to modeling the effect of each photoreaction on the planet as a whole. 

 

We are also fortunate to have access to an atmospheric monitoring station at Mammoth Cave National Park. We are in the process of mining years of observational data as we correlate precipitation and solar irradiance with NO an NOy levels.