Threshold effects in I-•CH3CN and I-•H2O cluster anion detachment: The angular distribution as an indicator of electronic autodetachment

I-center dot H2O and I-center dot CH3CN cluster anion photodetachment properties (photoelectron spectra and angular distributions) are recorded via velocity mapped photoelectron imaging for wavelengths between 270 and 340 nm, in small energy increments. These are compared with free I- detachment results and reveal the presence of a sharp change in the angular distribution for the P-2(3/2) spin orbit channel in the vicinity of the P-2(1/2) threshold. The effect is seen at this threshold in the I-center dot H2O cluster anion and just below threshold for I-center dot CH3CN. The effect is attributed to an electronic autodetachment process, which is dependent on electronic energy transfer mediated by the electron-neutral complex produced in the excitation process. These results highlight the potential of cluster anion detachment as a probe of electron-molecule interactions and in particular the sensitivity of the angular distributions to intracluster electron transfer processes.