UTILIZATION OF STIMULATED RAMAN EXCITATION AND COHERENT ANTI-STOKES-RAMAN SCATTERING IN STUDIES OF BOND-SELECTIVE AND MODE-SELECTIVE CHEMISTRY

The state resolved photodissociation of rovibrational states of the fu ndamental symmetric stretch of water, H2O (1,0,0), and of the O-H or O -D stretch vibrations of HOD was studied using laser induced fluoresce nce and Doppler polarization spectroscopy. The control that the initia lly selected state exerts over the product state distribution, vector correlations and bond selectivity was demonstrated. The specific energ y deposition via the lowest level of vibrational excitation leads to t he enhancement of bond breaking and to structured rotational state dis tributions of the OH fragment which depends on the prepared rotational state of the parent. The correlations are close to the maximum attain able values expected for an idealized orientation where the transition dipole moment of the parent is parallel to the fragment angular momen tum and perpendicular to its velocity. The photodissociation of HOD in which the O-H stretch is initially excited, leads to enhanced bond br eaking and selective production of OD + H, while when the O-D is excit ed no enhancement is obtained. These results show that which prepare t he parent molecule in a particular state before a second laser dissoci ates it, provide a powerful means for bond- and mode- slective chemist ry and molecular dynamics studies.