Real-time spectroscopy of isomerization process in azobenzene

Summary form only given. Azobenzene and its derivatives are known as typical molecules showing the trans-cis photoisomerization and are studied for basic understanding of the fundamental chemistry. There are two mechanisms which are proposed for photoisomerization process of azobenzene and its derivatives. One is the rotation of phenyl ring around the azo bond, and the other is the in-plane inversion of phenyl ring at one of the two N-atoms. We have investigated the real-time dynamics of molecular vibration in the excited state of trans-DMAA-B [methyl yellow; 4-(dimethylamino)azobenzene] in dimethyl-sulfoxide solution by pump-probe spectroscopy.