PT Unknown AU Beck, M Klammer, M Lang, S Leiderer, P Kabanov, VV Gol’tsman, GN Demsar, J TI Energy-gap dynamics of superconducting NbN thin films studied by time-resolved terahertz spectroscopy PY 2011 DE NbN thin film; energy gap dynamics AB Using time-domain Terahertz spectroscopy we performed direct studies of the photoinduced suppression and recovery of the superconducting gap in a conventional BCS superconductor NbN. Both processes are found to be strongly temperature and excitation density dependent. The analysis of the data with the established phenomenological Rothwarf-Taylor model enabled us to determine the bare quasiparticle recombination rate, the Cooper pair-breaking rate and the electron-phonon coupling constant, \lambda = 1.1 +/- 0.1, which is in excellent agreement with theoretical estimates. ER