Theory of photon-assisted tunneling in the transition between the quantum mechanical and classical limits

We report unpublished experimental results of photon-assisted tunneling (PAT) in the transition region between the quantum mechanical and classical limits. Using these results, we show that there is a discrepancy between the Tien-Gordon theory of quasiparticle photon-assisted tunneling and experiment in this region. Finally, we show that the modified Tien-Gordon theory is also valid in this region. (orig.)