Ultrafast heat transfer on nanoscale in thin gold films
Poletkin, Kirill V.
Gurzadyan, Gagik G.
Date of Issue2012
School of Mechanical and Aerospace Engineering
School of Physical and Mathematical Sciences
Heat transfer processes, induced by ultrashort laser pulses in thin gold films, were studied with a time resolution of 50 fs. It is demonstrated that in thin gold films heat is transmitted by means of electron–phonon and phonon–phonon interactions, and dissipated on nanoscale within 800 fs. Measurements show that the electron–phonon relaxation time varies versus the probe wavelength from 1.6 to 0.8 ps for λ = 560–630 nm. Applied mathematical model is a result of transforming the two-temperature model to the hyperbolic heat equation, based on assumptions that the electron gas is heated up instantaneously and applying Cattaneo’s law to the phonon subsystem, agrees well with the experimental results. This model allows us to define time of electron–phonon scattering as the ratio of the heat penetration depth to the speed of sound in the bulk material that, in turn, provides an explanation of experimental results that show the dependence of the electron–phonon relaxation time on the wavelength.
DRNTU::Engineering::Mechanical engineering::Fluid mechanics
Applied physics B: lasers and optics
© 2011 Springer-Verlag. This is the author created version of a work that has been peer reviewed and accepted for publication by Applied Physics B: Lasers and Optics, Springer-Verlag. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [DOI: http://dx.doi.org/10.1007/s00340-011-4862-z].