Novel Methods to Detect Trace Quantities of 1-ethyl-3-methylimidazolium tetrafluoroborate

View Video Presentation: https://doi.org/10.2514/6.2023-1410.vid

Reliable surface detection of deposited propellant is critical to studying overspray, a primary lifetime limiting mechanism of electrospray thrusters. This work explores four methods for the detection of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4), a room-temperature ionic liquid commonly used as propellant in electrospray thrusters: fluorescent spectroscopy, energy-dispersive X-ray spectroscopy, nonvolatile residue spectroscopy, and Fourier transform infrared spectroscopy. Successful detection of EMI-BF4 deposited onto a gold plated quartz crystal substrate by an electrospray source is demonstrated using energy-dispersive X-ray spectroscopy. Nonvolatile residue spectroscopy is shown to be capable of detecting highly diluted EMI-BF4. Fourier transform infrared spectroscopy was performed on a large drop of EMI-BF4 and differentiation between similar molecules was established. Initial surface contamination studies using UV-Vis fluorescent spectroscopy to detect the presence of EMI-BF4 on quartz crystal substrates are also conducted.