Investigation of the nonlinear absorption of[M(Et2timdt)2 ] (M = Pd, Pt) in the pico- and nanosecond timescales using the Z-scan technique

Abstract

The nonlinear optical absorption of two neutral metal dithiolenes[M(Et2timdt)2](M = Pd and Pt) has beeninvestigated at λ = 1064 nm by the open-aperture Z-scan technique using nanosecond and picosecond pulses. Forpicosecond photoexcitation, both dithiolenes mainly exhibit saturable absorption.Conversely, using nanosecond pulses, a switch from saturable absorption to reversesaturable absorption has been observed depending on the central metal. Based onexperimental results, energy-level structures are suggested to explain the nonlinearabsorption for both temporal regimes and, in particular, the sign-reversal of nonlinearabsorption.