We combine optical trapping and far-field optical detection techniques in a novel approach to study single metal nanoparticles in solution. We demonstrate the first measurements of the acoustic... Show moreWe combine optical trapping and far-field optical detection techniques in a novel approach to study single metal nanoparticles in solution. We demonstrate the first measurements of the acoustic vibrations of single gold nanoparticles optically trapped in water, and find evidence for intrinsic damping mechanisms. Additionally, we explore the potential of single gold nanorods as ultra-small mechanical actuators: we quantify the optical forces and torques on a single trapped gold nanorod (25 nm diameter and 60 nm length) and show that the rod can simultaneously exert forces and torques that would be large enough to manipulate single (macro-) molecules. We developed techniques to measure the combined translational and rotational Brownian motion of a trapped nanorod. We determine the rod's heating by the trap beam and show that translational and rotational Brownian motion of a hot particle are described by different effective temperatures and viscosities. Show less
This thesis explores how rheology and statistical mechanics can be used to describe driven granular materials. Chapter 1 is an overview of the current knowledge of slow granular flows. In Chapter 2... Show moreThis thesis explores how rheology and statistical mechanics can be used to describe driven granular materials. Chapter 1 is an overview of the current knowledge of slow granular flows. In Chapter 2 we characterize the liquid-like behaviour of a granular system excited by flow in a split-bottom geometry. In Chapter 3 we describe the fluctuations experienced by an object floating in our granular liquid and compare these fluctuations to the Brownian motion of particles in a thermal system. In Chapter 4 we characterize the motion of objects moving in a granular system excited by oscillatory flow. Finally, in Chapter 5, we describe both the microscopic and macroscopic motion of pucks on an air hockey table. We find the the system exhibits equipartition of rotational and translational energy and that the system can be described by van der Waals' equation of state. Show less
