Mechanical Properties of Small Metal Spheres and Rods

Abstract

Over the last two decades, considerable interest has focussed on the synthesis of quantum dots and small metal crystallites. In particular, the optical, magnetic and electrical properties of small particles have been intensively investigated. In addition, an understanding of fundamental material properties such as melting point, Young’s modulus and shear modulus will be essential if these particles are to be employed in nanoscale devices, motors or electronics. A vexed issue is establishing how one can probe mechanical properties such as rigidity or density, which appear to require manual contact with the materials. Recent work by several research groups has established that for metals such as gold and silver with pronounced surface plasmon resonances, laser excitation can cause rapid heating of the particle lattice [1, 2]. The heating excites phonon modes, which can be monitored spectroscopically in the femto- to nanosecond time regime. In this report we summarise some of our recent results on relaxation in laser excited nanoparticles. A fuller account is given in the parent articles and references therein.