Direct measurement of the total reaction rate of OH in the atmosphere

A new method to investigate atmospheric chemical kinetics is presented. It is based on the pump and probe principle. Preliminary measurements are desc ribed on the decay rate of OH in the planetary boundary layer after its con centration has been raised by laser flash photolysis of background ozone an d subsequent reaction of the O(1D) with atmospheric water vapor. The measur ed OH disappearance kinetics are compared with model calculations yielding information on the fast reaction of OH. The presented point measurements ca n be extended to a range resolved differential absorption LIDAR technique.