Measurements of Cl-atom photofragment angular momentum distributions in the photodissociation of Cl-2 and ICl

We have studied the complete Cl-atom molecular-frame photofragment angular momentum distributions from the photodissociation of Cl-2 and ICl in the 32 0-560 nm region using time-of-flight mass spectroscopy with laser detection . The experimental signals were analyzed using the polarization-parameter f ormalism described in the preceding paper. These experiments study three di stinct cases. The first case is the 470 nm dissociation of Cl-2 through the B (3)Pi(0+u) state accessed via a parallel transition, yielding Cl-atom ph otofragments with polarizations described by the single parameter a(0)((2)) (parallel to) = -0.7+/-0.2. The second case is the 320 nm dissociation of C l-2 through the C (1)Pi(1u) state accessed via a perpendicular transition, yielding Cl-atom photofragments with polarizations described by the two par ameters a(0)((2))(perpendicular to)= -0.50+/-0.10 and a(2)((2))(perpendicul ar to) = -0.32+/-0.06. The third case is the dissociation of ICl in the 490 -560 nm region in which dissociative states of both parallel and perpendicu lar character are accessed. In this wavelength region, the polarizations of the resulting Cl-atom photofragments are completely described by the appro ximately constant incoherent parameters, a(0)((2))(parallel to) approximate to + 0.4, a(0)((2))(perpendicular to) approximate to -0.2, and a(2)((2))(p erpendicular to) approximate to -0.2, whereas the interference contribution s to the polarization, the Im[a(1)((1))(parallel to,perpendicular to)] and Re[a(1)((2))(parallel to,perpendicular to)], oscillate sinusoidally with ex citation wavelength in a fashion that is sensitive to the shapes of the dis sociative surfaces. (C) 1999 American Institute of Physics. [S0021-9606(99) 01707-9].