X-ray and Electron Energy Loss Spectroscopy in Liquids in the Analytical S/TEM

As in-situ studies of dynamic processes in gases and liquids in the transmission and scanning transmission electron microscope (TEM/STEM) become routine [1] the need to go beyond imaging to more fully characterize complex microstructures during in-situ experiments becomes paramount. The use of both x-ray energy dispersive (XEDS) and electron loss spectroscopy (EELS) in conventional (vacuum) TEM is now routine. During gas/solid in-situ studies EELS has been used successfully [2], however, this has not been the case for studies in liquids [3] and XEDS has only recently been successful reported [4]. This is due to two factors namely: 1) multiple inelastic scattering in the liquids making EELS impractical and 2.) physical limitations which virtually preclude x-ray measurements in conventional liquid cell S/TEM holders. Recent modifications to holders and optimization of detectors has allowed us to overcome the former limitation [4]. In this work we present results using a modified Protochips Poseiden P200 holder in an FEI Tecnai F20 and CM200F TEMs operated at 200 kV. Nanoparticle specimens were encapsulated between a pair of 50 nm thick SiN windows having a nominal 150 nm gap in a commercial Si/SiNx eCell surrounded by both gaseous and liquid media.