Convolution effects in superconductive tunneling.

The quasiparticle density of states (DOS) of superconductors can be obtained from tunneling spectroscopy. When the normal-state differential conductance varies on the voltage scale comparable to that of strong-coupling effects, the standard normalization rule to extract the DOS is invalid, and the DOS is related to the measured data via an integral equation. These effects are exemplified by studying the geometry effect on the DOS for simple BCS superconductors. We apply these considerations to UPd2Al3 tunnel data where the apparent strong-coupling effects, previously deduced by use of the normalization rule, can be quantitatively attributed to convolution effects.