Direct measurement of quasiparticle-lifetime broadening in a strong-coupled superconductor

We have measured the quasiparticle recombination time in the strong-coupled superconductor Pb/sub 0.9/Bi/sub 0.1/ directly by measuring the lifetime-broadened energy gap edge. This is done by measuring the I-V characteristics of a superconducting tunnel junction of the type Pb/sub 0.9/Bi/sub 0.1/-insulator- Pb/sub 0.9/Bi/sub 0.1/. Agreement with the calculated value is excellent.