  A finite-time fluctuation theorem is proved for the diffusion-influenced
surface reaction A<->B in a domain with any geometry where the species A and B
undergo diffusive transport between the reservoir and the catalytic surface. A
corresponding finite-time thermodynamic force or affinity is associated with
the symmetry of the fluctuation theorem. The time dependence of the affinity
and the reaction rates characterizing the stochastic process can be expressed
analytically in terms of the solution of deterministic diffusion equations with
specific boundary conditions.
