Valerio Ferracci

Recreating the Earth's Atmosphere


Gas-phase reactions involving highly reactive free radicals are commonplace in the Earth's atmosphere. Laser flash photolysis is a powerful technique which enables atmospheric chemists to generate transient species, such as short-lived radicals, and study their reactivity in the laboratory. In this video Valerio Ferracci illustrates the principles of this method: a laser pulse photolyses gas-phase precursor to produce the radicals of interest, which then react away. The change in concentration of these radicals over time is monitored through UV/visible absorption spectroscopy and allows the determination of important information concerning the rates of atmospheric reactions. These kinetic data are vital to understand phenomena such as smog formation and stratospheric ozone depletion and to build accurate models of the atmosphere.

This film has been produced and directed by UCL alumnus Alom Shaha - www.whyscience.co.uk