Ionic liquids in vacuo: analysis of liquid surfaces using ultra-high-vacuum techniques

Ultra-high-vacuum (UHV)-based techniques can offer the scientist a tremendous amount of information about samples of interest. However, until recently the range of samples that could be routinely investigated using unmodified instrumentation was limited to solid samples and frozen solutions. In this paper we report the investigation of low-vapor-pressure, liquid samples using both X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. We demonstrate the suitability of UHV techniques in the investigation of a range of room-temperature ionic liquids, offering the opportunity to measure high-quality solution-phase spectra using unmodified instrumentation.