This work explores novel methods for probing neutral species in electrospray plumes by leveraging energy dependent surface impact processes such as deposition, erosion, and secondary species production. A variable energy single emitter ionic liquid ion source (ILIS) operating in the pure-ion regime (PIR) was used to control the energy of the ion plume impacting probes and targets to understand how the energy of impacting species affects detection. A quartz crystal microbalance (QCM) is used to measure the deposition of propellant from low-energy ion plumes and removal of surface material from high-energy ion plumes. Surface analysis and imaging techniques are used to confirm trace propellant accumulation on targets and probes, as well as to make estimations of total propellant content, with greater propellant accumulation rates driven by lower-energy plumes. A probe was implemented to measure the content of charged secondary species produced from surface impacts and demonstrated successful detection of neutrals in the plume.