1. Electron Transfer in cluster Anions:
Dissociative Attachment Processes in Real Time
Richard Mabbs, Chemistry Department, Washington University in St. Louis
O2- l
O2(v’) + e-
I-·CH3I (350 nm)  I + CH3I + e-
 I + CH3 + I- I II
Photodetachment imaging studies of O2- clearly show that both the parent orbital and the vibrational level of the neutral O2 are important in determining the angular distributions. The internal excitation of the neutral has an important role in the photodetachment dynamics. I II
I-·CH3I detachment
at 350 nm. ep
(I) The angular distribution of the photoelectrons from the I-·CH3I cluster anion peaks parallel to the laser polarization axis. This is in contrast to the photodetachment from a free I- anion. Scattering of the departing electron from the methyl iodide is responsible. Changing the contrast ratio in the image reveals the presence of a fragmentation channel corresponding to a dissociative attachment process (II). Initiation with a fs laser pulse brings the promise of following the dynamics of the process in real time, the subject of ongoing studies in our research group.
O2- (v=0)O2 (v=2)
The photoelectron angular distribution, is characterized by the anisotropy parameter b. Changes in b with electron kinetic energy (eKE) are described very well within an atomic-like detachment model1 for a given vibronic transition but each vibronic band must be treated separately.
1Hanstorp et al. Phys Rev A 40, 670, (1989)
Excitation
pulse
Probe
pulse
X-Y
XY-
X+Y+ e-