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In this work, we investigate the time-resolved photoelectron spectra of IBr$-$(CO$2$).}, {\bf{2010}}, {\it{in press}}.} In the photodetachment studies performed by Lineberger and co-workers, IBr$-$(CO$2$) is prepared in its electronic ground state ($2\Sigma 1/2+$) whereupon it is excited to its {\it{~{A}}} ($2\Pi 3/2$) excited state, before electron photodetachment/photoionization and dissociation on the {\it{~{C}}} ($1\Pi 1$) excited state of IBr. Previous experimental work showed that dissociation of bare IBr$-$ yields only I$-$ + Br products.}, {\bf{2005}}, {\it{122}}, 174305.} However in IBr$-$(CO$2$), a small fraction ($\sim$ 3%) of the dissociating molecules undergo an electron transfer from I to Br at 350 fs after the initial excitation. Thus a single solvent molecule can initiate a non-adiabatic transition from the {\it{~{A}}} state to either the lower {\it{~{A}}} or {\it{~{X}}} state, thereby producing I + Br$-$ (+ CO$2$) prior to photoionization. To study the dynamics, we perform high level {\it{ab initio}} calculations (MR-SO-CISD/aug-cc-pVTZ(-PP)) as well as classical molecular dynamics (MD) simulations. The MD simulations capture much of the dynamics of the photodissociation but underestimate the charge-transfer channel. Results of the {\it{ab initio}} calculations show how CO$2$ bend vibrational excitation could increase the percentage of non-adiabatic transitions and how the CO$2$ modifies the charge distribution of IBr$-$ to make the charge transfer accessible. The proposed mechanism and timescales are consistent with the observed Br$-$ products.