For the pair {−Δ,−Δ−αδC​} of self-adjoint
Schr\"{o}dinger operators in L2(Rn) a spectral shift function is
determined in an explicit form with the help of (energy parameter dependent)
Dirichlet-to-Neumann maps. Here δC​ denotes a singular
δ-potential which is supported on a smooth compact hypersurface
C⊂Rn and α is a real-valued function on
C.Comment: 22 pages, this was originally part of arXiv:1609.08292, the latter
will soon be resubmitted to the archive in a shortened form that is to appear
in Math. Annale