J. Phys. IV France 12 (2002) Pr9-303
DOI: 10.1051/jp4:20020420

Optically induced coherent voltage oscillations in K _0.3MoO ₃

P.H.M. van Loosdrecht¹, B. Beschoten², I. Dotsenko² and S. van Smaalen<sup>3

1</sup>  Materials Science Center, University of Groningen, Nijenborg 4, 9747 AG Groningen, The Netherlands
²  II. Physikalisches Institut, RWTH-Aachen, Templergraben 55, 52056 Aachen, Germany
³  Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany

Abstract
Optical induced transient changes of the electrical conductivity are investigated in the non-linear transport regime of the blue bronze K _0.3MoO ₃ below its Peierls transition using the impulsive infrared excitation of a free-electron laser a t energies above the Peierls gap. The transients of the sample voltage have typical relaxation times of 0.5-2 ms superimposed by coherent voltage oscillations, which exhibit lifetimes of up 100 ms. The frequency of those voltage oscillation is found to be time dependent. This, in comparison with voltage oscillations purely driven by static electrical fields, enables the study of quasiparticle dynamics in the charge density condensate of the blue bronze.

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