We present a new method to measure the diffuse scattering of amorphous
multilayers. In contrast to conventional scans, that all take place i
n the plane of reflection, in this out-of-plane scattering geometry th
e accessible range in parallel momentum transfer Q(parallel-to) is not
limited by the sample surface. We can therefore record data continuou
sly from very small Q(parallel-to) up to Q(parallel-to) congruent-to 2
pi/lambda, holding Q(perpendicular-to) constant at the same time. We t
hereby obtain a scattering factor S(Q) of our sample, that can easily
be attributed to diffuse scattering at rough interfaces or amorphous b
ulk, respectively. In the case of the W/C amorphous multilayer studied
here, the data show that the contribution of amorphous scattering is
less than 2% up to about Q(parallel-to) = 0.1 angstrom-1, and becomes
dominant only in the wide angle region. This allows to draw the conclu
sion, that the Bragg sheets observed in the vicinity of the specular c
ondition are mainly due to conformal roughness of the multilayer inter
faces.