Question: Particular solution to diffusion equation

Hello, I have a question concerning a PDE with specific IC/BC, that describes diffusion of a species in a moderately solid thin film with a finite thickness on a solid substrate that is considered semi-infinite. The thin film has an impermeable boundary at x = -h, and the interface between the thin film and the substrate occurs at x=0.  It is possible that the species of interest may be substantially depleted from the substrate, depending on how long the experiment runs.  I am not sure that I have set up the code correctly, and am using Maple 11.

The general solution to my PDE is (I used the unprotect D command) 

> PDE := D*diff(c(x,t),t)=diff(c(x,t),x,x);

initially at t=0,

for -h<x<0, IC1:= C(x,0) = C0;

for 0<x<infinity, IC2:= C(x,0) = 0;

the boundary condition are

> BC1 := diff(c(-h,t))=0;    # impermeable boundary
> BC2 := diff(c(0,t))=diff(c(0,t)); # not sure how to express this, it just means that there is continuity of the diffusing species at the interface from the left and the right; that is, at t>0

 In this case I want to find the specific solution for c(x,t) . If you have any idea to solve this problem using this software, please help me.