Electron-Impact Resonances of Anthracene in the Presence of Methanol: Does the Solvent Identity Matter?

Electron impact resonances of neutral molecules can be probed using 2D photoelectron spectroscopy of their radical anions, with a core advantage of being able to introduce solvent molecules in a systematic manner through clustering. This approach has been employed previously to probe the effect of water molecules on the resonances of anthracene. Here, we extend this study to probe the resonances of anthracene in the presence of methanol. We find that the nature of the solvent has little impact on the resonances from the perspective of the anion. Only the electron affinity is observed to increase, which corresponds to a concomitant decrease in resonance energy as viewed from a free electron impacting the anthracene-methanol cluster. For a critical cluster size, ncritical, the lowest resonance becomes a bound state and the mechanism for electron loss switches from a prompt autodetachment process to a statistical thermionic emission process. We posit that the identity of a general solvent molecule only impacts the stabilization of the resonances of anthracene, which in turn affects the overall decay mechanism and ncritical, but the inherent resonance dynamics of anthracene is unaffected by the solvent.