Investigation of possible illusion in catalyst surface/interface electric fields resolved by differential phase contrast
In order to address electron inaccuracies in analyzing surface electric field of catalysts using differential phase contrast(DPC)technique,an electron microscopy image simulation method was proposed.DPC imaging simulations were performed on heterogeneous interfaces and irregular particle edges to analyze electric field information through DPC and electric field relationship.Subsequently,the DPC results of particle edges and heterogeneous interfaces under different defocus and astigmatism were simulated with real imaging parameters using a FEl-Titan Themis Cubed G2 60-300 microscope.The results reveal that the scattering differences of heterogeneous atoms by electron beam causes additional displacement of atomic electric field at the interface.For samples with irregular interfaces,the irregular surface shape results in additional beam deflections and leads to inaccurate determination of electric fields at the interface.As sample thickness increases,the electron beam generates phase shift,and leads to inaccuracies in atomic inter-electrostatic field measured by DPC.Moreover,reducing defocus amount during DPC imaging is necessary to avoid false electric field inversion or displacement caused by defocus.The value of third-fold astigmatism during imaging processes needs to be focused and adjustments should be made in a timely manner to obtain more accurate DPC results.
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