title: Athermal photofluidization of glasses.
abstract: Azobenzene and its derivatives are among the most important organic photonic materials, with their photo-induced trans-cis isomerization leading to applications ranging from holographic data storage and photoalignment to photoactuation and nanorobotics. A key element and enduring mystery in the photophysics of azobenzenes, central to all such applications, is athermal photofluidization: illumination that produces only a sub-Kelvin increase in average temperature can reduce, by many orders of magnitude, the viscosity of an organic glassy host at temperatures more than 100 K below its thermal glass transition. Here we analyse the relaxation dynamics of a dense monolayer glass of azobenzene-based molecules to obtain a measurement of the transient local effective temperature at which a photo-isomerizing molecule attacks its orientationally confining barriers. This high temperature (T(loc)~800 K) leads directly to photofluidization, as each absorbed photon generates an event in which a local glass transition temperature is exceeded, enabling collective confining barriers to be attacked with near 100% quantum efficiency.
authors: Department of Physics and Liquid Crystal Materials Research Center, University of Colorado, Boulder, Colorado 80309, USA.
authors: G J
authors: GJ
authors: Fang
authors: J E
authors: JE
authors: Maclennan
authors: Y
authors: Y
authors: Yi
authors: M A
authors: MA
authors: Glaser
authors: M
authors: M
authors: Farrow
authors: E
authors: E
authors: Korblova
authors: D M
authors: DM
authors: Walba
authors: T E
authors: TE
authors: Furtak
authors: N A
authors: NA
authors: Clark