TY - JOUR
T1 - Interferometric Diffraction from Amorphous Double Films
AU - Rezikyan, Aram
AU - Belcourt, James A.
AU - Treacy, Michael M.J.
N1 - Publisher Copyright:
© © Microscopy Society of America 2015.
PY - 2015/3/5
Y1 - 2015/3/5
N2 - We explore the interference fringes that arise in diffraction patterns from double-layer amorphous samples where there is a substantial separation, up to about a micron, between two overlapping thin films. This interferometric diffraction geometry, where both waves have interacted with the specimen, reveals phase gradients within microdiffraction patterns. The rapid fading of the observed fringes as the magnitude of the diffraction vector increases confirms that displacement decoherence is strong in high-energy electron scattering from amorphous samples. The fading of fringes with increasing layer separation indicates an effective illumination coherence length of about 225 nm, which is consistent with the value of 270 nm expected for the heated Schottky field emitter source. A small reduction in measured coherence length is expected because of the additional energy spread induced in the beam after it passes through the first layer.
AB - We explore the interference fringes that arise in diffraction patterns from double-layer amorphous samples where there is a substantial separation, up to about a micron, between two overlapping thin films. This interferometric diffraction geometry, where both waves have interacted with the specimen, reveals phase gradients within microdiffraction patterns. The rapid fading of the observed fringes as the magnitude of the diffraction vector increases confirms that displacement decoherence is strong in high-energy electron scattering from amorphous samples. The fading of fringes with increasing layer separation indicates an effective illumination coherence length of about 225 nm, which is consistent with the value of 270 nm expected for the heated Schottky field emitter source. A small reduction in measured coherence length is expected because of the additional energy spread induced in the beam after it passes through the first layer.
KW - amorphous double layer
KW - interference fringes
KW - interferometric diffraction
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U2 - 10.1017/S1431927615014981
DO - 10.1017/S1431927615014981
M3 - Article
AN - SCOPUS:84943546068
SN - 1431-9276
VL - 21
SP - 1348
EP - 1360
JO - Microscopy and Microanalysis
JF - Microscopy and Microanalysis
IS - 5
ER -