Dipole moment effects in photodetachment from cluster anions

In this dissertation results from experimental studies on the effect of the dipole moment on photodetachment from solvated iodide anion are presented. The major advantage of using solvated atomic iodide anions: I<super>&minus;</super>&middot;(Y)_{<italic>n</italic>}: Y = solvent molecule, <italic>n</italic>=1 to 3)) to study this effect is that in the ground state, the excess electron is mainly localized on the iodine atom for which photodetachment behavior is well understood. The effect of the electric dipole moment of the resultant neutral cluster on the outgoing electron is studied by comparing the photoelectron angular distributions: PADs) for I<super>&minus;</super>&middot;(Y)_{<italic>n</italic>} and I<super>&minus;</super> photodetachment. The results show strong dipole moment effects in the vicinity of direct detachment thresholds due to the presence of dipole-supported states, [I: <super>2</super>P_3/2)&middot;(Y)_{<italic>n</italic>}] <super>&minus;</super> and I(<super>2</super>P_1/2)&middot;(Y) _{<italic>n</italic>}]<super>&minus;</super>. Vertical photoexcitation near the threshold for production of the excited neutral cluster I(<super>2</super>P_1/2) &middot;(Y)_{<italic>n</italic>} shows evidence of strong mixing of the direct: I<super>&minus;</super>&middot;(Y)_{<italic>n</italic>}&rarr; I: <super>2</super>P_3/2) +: Y)_{<italic>n</italic>} + e<super>&minus;</super>) channel and a dipole-supported state, [I(<super>2</super>P_1/2)&middot;(Y) _{<italic>n</italic>}]<super>&minus;</super> in the PADs. It is shown that increasing the dipole moment of I(<super>2</super>P_1/2)&middot;(Y)_{<italic>n</italic>} for <italic>n</italic>=1 increases this channel coupling while for <italic>n</italic> > 1, the situation is more complex due to competing dynamics. Results are also presented for photodetachment from a stable dipole-bound CH₃CN<super>&minus;</super> anion in the vicinity of a well-known electron scattering resonance. Despite the presence of this &pi; *_CN it appears to have very little effect on the photoelectron angular distributions. This initially surprising behavior is attributed to the relatively low contribution of higher partial angular momenta waves in the detachment process.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Year dc:date.available

2011

Author dc:creator

• Mbaiwa, Foster

Contributors dc:contributor

• Richard Mabbs

• Physical chemistry
• Cluster anions
• Dipole-bound anions
• Dipole moment
• Photodetachment
• Photoelectron
• Photoelectron angular distributions

Language dc:language

English (en)

DOI

https://doi.org/10.7936/K7C24TG2

OAI identifier oai:identifier

oai:openscholarship.wustl.edu:etd-1612