CEMAS 2021 Workshop: Advanced direct detection EELS
This virtual workshop is hosted by the Center for Electron Microscopy and Analysis (CEMAS), Ohio State University. Space is limited. For registration and program details, please visit https://cemas.osu.edu/events or contact Dr. David McComb.
January 13, 2021 (EST, USA)
- 1:00 – 1:30 p.m.: EELS presentation
- 1:30 – 4:30 p.m.: Live EELS analysis using CEMAS samples
Indirect cameras (IDC) for electron detection convert high-energy incident electrons to photons which, through a fiber-optic network or lens, are coupled to a camera, typically a CCD or CMOS. This indirect detection method inherently limits the camera’s point spread function (PSF) and detection quantum efficiency (DQE). Over the last decade, radiation-tolerant CMOS active pixel sensors, which directly image high energy incident electrons, have been developed with much-improved PSF and DQE in comparison to conventional IDCs. Such direct detection (DD) cameras have been successfully utilized in cryo-TEM and in-situ TEM for both imaging and diffraction. Owing to this big improvement in the PSF, electron energy loss spectroscopy (EELS) spectra can be acquired over large fields of view while maintaining the energy resolution unchanged. Such DD camera detectors can be operated in counting mode where each electron that falls onto a pixel in the camera can be distinguished and the charge isolated. The result is a dramatic increase in the resolution and reduction of all the additional sources of noise typically those related to the fiber optic, gain, and dark contributions. The shot noise is now the only source of noise present and the implication in the acquisition of EELS spectra is that chemical analysis becomes more straightforward and in the case of low signal even possible. These improvements offered by the DD camera have a wide range of applications including efficient and low-dose spectrum imaging, trace element detection and analysis, and time-resolved EELS.
This CEMAS workshop will begin with a brief presentation on direct detection technology for EELS data acquisition and the key benefits and utilities of DD cameras for EELS. The lecture will be corroborated with live remote demonstrations on a Gatan Quantum K2 imaging filter system analyzing CEMAS samples. Throughout the interactive event, open discussion and Q&A on all topics presented and demonstrated are encouraged. For more information on Gatan DD EELS technology, please contact Bill Flosi.
Paolo Longo, Ph.D., Gatan