Abstract
A spectroscopic method has been developed to study chemical reaction processes through in situ observation of the time profile of molecular absorptions in the millimeter- and submillimeter-wave regions. The method has been applied to oxidation reactions of unsaturated hydrocarbons initiated by mercury photosensitization. It has also been combined with the excimer laser photolysis to examine photodecomposition processes of SO2, CS2, and Cl2SO, where nascent distributions of photofragments such as SO and CS were measured. Advantages and disadvantages of the method have been discussed in some detail.