Other subjects explored include hydrogen bonding effects on the photochemistry of chromophores in solution, photochemical generation of silicon-centered radicals and their reactions, and photochemical processes at the air-water interface of atmospheric droplets.
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class of psychoactive drugs. It is the world's most widely consumed psychoactive drug, but unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world.
More people use caffeine on a daily basis than any other psychoactive drug. Caffeine belongs to a class of compounds known as xanthines, which are the oldest known stimulants. Other closely related xanthines are theophylline and theobromine. Three plants containing xanthines have been used by humans for thousands of years.