Extended Data Fig. 1: Experimental vibrational EELS set-up and phonon dispersion curves.
From: Nanoscale imaging of phonon dynamics by electron microscopy
a, Schematic of the STEM EELS experimental set-up. An electron beam with a convergence semi-angle of α = 33 mrad is focused to form a 1.5 Å wide probe on the sample. Electrons are then elastically and inelastically scattered by the sample. High-angle scattered electrons are recorded by the HAADF detector. The lower-angle scattered electrons enter the spectrometer with a collection semi-angle of β = 25 mrad and are dispersed based on energy. Elastically scattering electrons form the ZLP while inelastic electrons contribute to the vibrational signal. b–d, Phonon dispersion relations of bulk Si, Ge, and disordered Si0.5Ge0.5 respectively. e–g, Total phonon density of states of bulk Si, Ge, and Si0.5Ge0.5 respectively. h–j, Calculated phonon density of states of Si, Ge and Si0.5Ge0.5 QD respectively after convolution with a Gaussian of width 7meV.
