title: Exploring the dynamics of superconductors by time-resolved far-infrared spectroscopy.
abstract: We have examined the recombination of excess quasiparticles in superconducting Pb by time-resolved far-infrared spectroscopy using a pulsed synchrotron source. The energy gap shift calculated by Owen and Scalapino [Phys. Rev. Lett. 28, 1559 (1972)] is directly observed, as is the associated reduction in the Cooper pair density. The relaxation process involves a two-component decay; the faster ( approximately 200 ps) is associated with the actual (effective) recombination process, while the slower ( approximately 10 to 100 ns) is due to heat transport across the film/substrate interface. The temperature dependence of the recombination process between 0. 5T(c) and 0.85T(c) is in good agreement with theory.
authors.affiliation: National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA. carr@bnl.gov
authors.forename: G L
authors.initials: GL
authors.lastname: Carr
authors.forename: R P
authors.initials: RP
authors.lastname: Lobo
authors.forename: J
authors.initials: J
authors.lastname: LaVeigne
authors.forename: D H
authors.initials: DH
authors.lastname: Reitze
authors.forename: D B
authors.initials: DB
authors.lastname: Tanner