ISO 23420:2021 Microbeam analysis — Analytical electron microscopy — Method for the determination of energy resolution for electron energy loss spectrum analysis.
7.2 Predetermination of binding energy
7.2.1 Obtain graphite and the other reference sample
Obtain a graphite and a second reference sample. The graphite reference sample has a Carbon K-edge and an EEL peak E71 in an EEL spectrum. The second reference sample should have an EEL peak ECZLP appearing close to the zero-loss peak, hut the peak spread should not overlap with the zero-loss peak. For example, the boron nitride plasmon-loss (rt – ne) peak is suitable for the ECZLP as good as the graphite plasmon-loss Or + a) peak.
7.2.2 Measure Cis of graphite by using the XPS
Measure the carbon K-shell binding energy of the graphite using XPS. The Cls is used as carbon K edge energy ECK of graphite of the EELS. The XPS shall be calibrated by ISO 15472:20 10.
7.3 Setup of the S/TEM and the EELS, and sample setting
Samples are recommended to be drop-cast onto a TEM grid, e.g. a holey carbon film support grid, to
ease the measurement. The electron microscope should be adjusted for S/TEM observation in advance.
EELS should also be adjusted in advance so that EEL spectra can be easily obtained. Parameters of the
S/TEM and the EELS are recorded as described in 7.
The quality of an EEL spectrum is easily affected by electron beam induced carbon contamination. The use of an anti-contamination device is strongly recommended for suppression of the contamination. Additionally, a clean environment in the column is also needed to minimise the contamination.
7.4 First energy step, SE1, calibration
7.4.1 EELS acquisition set-up
Set the EEL spectrometer acquisition time and integration numbers so as to secure a sufficient signal-to-noise ratio without any peak saturation for all measurements, including measurements in subsequent sections. Since the measurement conditions such as irradiation current, entrance aperture diameter and capturing device characterization like CCD / CMOS camera are different, acquisition time and integration number cannot be uniformized. Therefore, users of this procedure should optirnise acquisition time and integration number for their own systems and should record these values.ISO 23420 pdf download.