In this work, we study a mesh termination scheme in acoustic scattering, kn
own as the perfectly matched layer (PML) method. The main result of the pap
er is the following. Assume that the scatterer is contained in a bounded an
d strictly convex artificial domain. We surround this domain by a PML of co
nstant thickness. On the peripheral boundary of this layer, a homogenous Di
richlet condition is imposed. We show in this paper that the resulting boun
dary-value problem for the scattered field is uniquely solvable for all wav
enumbers and the solution within the artificial domain converges exponentia
lly fast toward the full-space scattering solution when the layer thickness
is increased. The proof is based on the idea of interpreting the PML mediu
m as a complex stretching of the coordinates in R-n and on the use of compl
exified layer potential techniques.