Cryo 4D-STEM Data Set: isotactic Polypropylene/ Ethylene-Octene Copolymer Interface

Sample: Data is taken of a iPP/EO (DOW ENGAGETM 8540) blend interface. The blend was cryo-microtomed to a nominal slice thickness of 50nm. Transmission electron microscopy was performed using the TEAM I microscope at the Lawrence Berkeley National Laboratory using a Gatan K3 detector and Continuum spectrometer.

Data Set 12: This work was performed at -185°C under liquid nitrogen cooling with a 300kV accelerating voltage and a semi-convergence angle of 0.5mrad which yielded a diffraction-limited probe with a full-width half-max of 2nm. The beam was rastered with a step size of 5nm over a 505 × 500nm2 field of view. The electron dose per sample area over the entire scan is 20 e-/Å2. However, 4D-STEM is a converged probe technique in which ~80% of the beam fluence is contained within 1.74 × the FWHM of the probe. Using 1.74 × the FWHM of the probe as the diameter to calculate the irradiated sample area yields a dose of 60 e-/Å2 for this data set.  Gold nanoparticles were used to calibrate the reciprocal space pixel size as well as measure the elliptical distortion present in the data set.

Data Set 18: This data was taken at -185°C under liquid nitrogen cooling with a 300kV accelerating voltage and a semi-convergence angle of 0.14mrad which yielded a diffraction-limited probe with a full-width half-max of 10nm. The beam was rastered with a step size of 10nm over a 1.4 × 1.4μm2 field of view. The electron dose per sample area over the entire scan was 0.50 e-/Å2 while the dose per probe area was 0.64 e-/Å2. Gold nanoparticles were used to calibrate the reciprocal space pixel size.

Data Set 19: This data was taken over the exact same area as Data Set 18 to give a comparison under larger dose accumulation. The data was obtained with the exact same parameters and under the same experimental conditions as Data Set 18.