Mj. Dewitt et al., PHOTOIONIZATION DISSOCIATION OF ALKYL SUBSTITUTED BENZENE MOLECULES USING INTENSE NEAR-INFRARED RADIATION/, Chemical physics, 218(1-2), 1997, pp. 211-223
The photoionization products for benzene, toluene, ethylbenzene and n-
propylbenzene are measured using time-of-flight methods upon interacti
on with 780 nm radiation pulses of duration 170 fs and intensity 10(13
-13.6) W cm(-2). The relative ionization yields scale as 1, 1.2, 1.4,
and 0.35 for benzene, toluene, ethylbenzene and n-propylbenzene at max
imum laser intensity. Limited dissociation was observed for benzene an
d toluene at all laser power densities. A significant (> 5%) dissociat
ion/ionization yield was observed for ethylbenzene and n-propylbenzene
at the lowest laser power densities. The dissociation increased as 11
th order and 9th order processes for ethylbenzene and n-propylbenzene,
respectively to a maximum of 70% dissociation/ionization for n-propyl
benzene at 3.8 X 10(13) W cm(-2). At 3.8 X 10(13) W cm(-2) the dissoci
ation yield increases quadratically with alkyl chain length for the se
ries. The observed ionization/dissociation trends are consistent with
a model which incorporates both Field ionization and energy redistribu
tion concepts.