Zusammenfassung
The velocity and angular distribution of NO fragments produced by UV photodissociation of nitrosobenzene have been determined by velocity-map ion-imaging. Excitation of the S-2-state by irradiation into the peak of the first UV absorption band at 290.5 nm leads to a completely isotropic velocity distribution with Gaussian shape. The average kinetic energy in both fragments correlates with the ...
Zusammenfassung
The velocity and angular distribution of NO fragments produced by UV photodissociation of nitrosobenzene have been determined by velocity-map ion-imaging. Excitation of the S-2-state by irradiation into the peak of the first UV absorption band at 290.5 nm leads to a completely isotropic velocity distribution with Gaussian shape. The average kinetic energy in both fragments correlates with the rotational energy of the NO fragment and increases from 6% of the excess energy for j = 6.5 to 11% for j = 29.5. A similar isotropic distribution albeit with larger average velocity is observed when the ionization laser at 226 nm is also used for photodissociation, corresponding to excitation into a higher electronic state S-n (n greater than or equal to 3) of nitrosobenzene. It is concluded that photodissociation occurs on a timescale much slower than rotation of the parent molecule, and after redistribution of the excess energy into the vibrational degrees of freedom.
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