Case Western Reserve researchers looking at light-induced toxins in air...(l exhaust and urban air pollution is ass...)

Previous research works have shown that light-induced degradation of a number of nitro-aromatic compounds leads to products that are more toxic than their parent compounds. Further evidence suggests that these pollutants contribute as much as 10% of the total mutagenicity of inhalable, suspended particles in polluted areas. However, the specific pathways through which these compounds are transformed into products by sunlight are not well understood.

The Crespo group expects that by using sophisticated laser techniques with less than a trillionth of a second time resolution, in combination with computations based on quantum mechanical theories, a better understanding of the fundamental processes controlling the light-induced transformation of these pollutants can be obtained.

"Once we understand the physico-chemical factors that control the degradation of these compounds by light absorption at the molecular level, we might be able to use this knowledge to reduce some of these chemical transformations."

It is known that these compounds can release a nitric oxide (NO) radical when exposed to light. Crespo says one of the long-term goals of this research is to harness the power of these radical compounds for biological applications.

"Once we understand the factors that control the release of NO radicals, we could envision the use nitro-aromatic compounds as light-triggered, time- and site-controlled NO radical donors for therapeutic applications," he says. "But we are currently a long way from that."

Their 2008 paper, "Environmental Photochemistry of Nitro-PAHs: Direct Observation of Ultrafast Intersystem Crossing in 1-Nitropyrene," was one of the first scholarly works using femtosecond laser
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