DualEELS™ allows you to acquire two optimized electron energy loss spectra from different energy ranges (typically one core-loss and one low-loss) in rapid succession. This spectral recording modality helps to overcome the large dynamic range encountered in electron energy loss spectroscopy (EELS) data. When you have both the core- and low-loss signals from an identical sample area, additional processing methods become practical. These additional methods include:
- Removal of energy shift to allow accurate chemical shift measurements
- Perform absolute quantification
- Assess sample thickness and deconvolve plural scattering
- Correlate low-loss signals with core-loss features (e.g., plasmonics, band gap)
A further application of DualEELS is to extend the energy range of EELS data through the acquisition of multiple core-loss spectra.
In the DualEELS implementation from Gatan, three ultrafast electrostatic deflectors are synchronized to create the final dataset: beam blanking control down to 1 µs (Quantum) and 100 ns (Continuum); energy shift control (up to 2 kV offset with 10 µs switching time); and lateral spectrum shift control to isolate two portions of the spectrum on the detector. The fast switching results in very high collection efficiency.The Gatan implementation was inspired by the work of groups at Glasgow, UK, and Orsay, France.
Scott, J.; Thomas, P. J.; MacKenzie, M.; McFadzean, S.; Wilbrink, J.; Craven, A. J.; Nicholson, W. A. P. "Near-simultaneous dual energy range EELS spectrum imaging", Ultramicroscopy 108 (2008) 1586.
Tencé, M.; Pinna, H.; Birou, T.; Guiraud, L.; Mayet, A.; Pertel, C.; Serin, V.; Colliex, C. 2006 "A new detector device designed for quantitative EELS spectroscopy", In Proc. IMC 16, Sapporo, Japan (eds Ichinose H.; Sasaki T.), pp. 824 – 825.