Bragg condition | Quasi-Bragg condition | Comment |
nλ ≈ dΘ | τmλ ≈ d'Θ' | Including metric, ('), n, m integral m = −infinity, −1, 0 1, 2, 3… or h' = 0, τ−1, 1,τ, τ−1, τ−2, τ−3… |
d = a/h | d' = a'/h' | r is fixed within known models |
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| Diffraction depends on harmonic r. h in SF for Equation (1) & QSF for (2) |
cs = 1 | cs < 1 | In quasi Bragg h' cs < h = 0.205 ´ cs nm = 0.205 ´ cs ´ τ = 0.296 nm, = a' |