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![[Figure 10]](ge5117fig10mag.jpg)
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Figure 10
Model calculations of the specular neutron reflectivity as a function of Q for different beam angular resolutions in the two limiting cases. In the left-hand plot the transverse dimension of the wavefront is of sufficient extent to completely average over a large enough number of the bars and troughs of the patterned film structure. Conversely, in the right-hand plot the transverse dimension of the wavefront was significantly less than the width of a bar or trough (bar width = trough width). The substrate was taken to be silicon with approximately 950 Å-thick nickel bars deposited on top. Neutrons were taken to be incident from vacuum. Both plots show specular reflectivity curves at two extremes of instrumental angular beam divergence, approximately 3.5 × 10−5 and 1.5 × 10−3 rad, at a fractional wavelength resolution of 0.01. Despite a difference of a factor of over 40 in the angular divergence of the beam and the consequential rounding of the critical edge and smearing of the film thickness fringes at the broader angular divergences, an unambiguous distinction between the cases for coherent averaging and incoherent sum can be made. |
![[Figure 10]](ge5117fig10.jpg)
 | JOURNAL OF APPLIED CRYSTALLOGRAPHY |
ISSN: 1600-5767
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