Australian Institute of Physics

South Australian Branch

Notice of the STUDENT NIGHT for 1997

7.30pm Tuesday 27th May, 1997

and of the presentation of Silver Bragg Medals
and of Claire Corani awards

in the KERR GRANT Lecture Theatre,
Physics Building, University of Adelaide

The Silver Bragg Medal is awarded for highest achievement in the final undergraduate year in Physics courses at each university in South Australia and the Northern Territory, while the Claire Corani award is for highest achievement by female students in second-year Physics. The presentation will be followed by short talks on their research work by postgraduate Physics students from each university in South Australia:

"Variable SBS Pulse Compressor for Nonlinear Optical Measurements"

by Patrick Klovekorn of the Dept. of Physics and Mathematical Physics, University of Adelaide

We have developed a novel method to measure the optical response of promising new materials using a phase conjugated laser system based on stimulated Brillouin scattering (SBS). Variable pulse compression of the said system provides pulses in the nanosecond to subnanosecond regime, exceptional beam quality and auto alignment. This presents us with the ability to excite selectively different physical mechanisms in a material with one inexpensive laser only and also fills the pulse length gap which exists between nanosecond and picosecond lasers. We confirm the utility of this system by demonstrating new nonlinear optical measurements in a liquid crystal.

"Surface Force Measurement Between Solid and Fluid Surfaces"

by Jason Connor of the School of Physics and Electronic Systems Engineering, University of South Australia

An understanding of the forces acting across thin liquid films is important for both fundamental and commercial reasons. Bubble/particle attachment; colloid stability; wetting and spreading dynamics; foam stability; and lubrication are all very important industrial processes in which surface forces play a key role. Thin aqueous films bound by the surfaces of mercury (a fluid) and mica (a solid) are being investigated using a new experimental technique. This novel technique combines features of the Israelachvili surface force apparatus and the dropping mercury electrode, enabling an experimenter to control and measure the forces (dynamic and equilibrium) acting across the liquid. The development of this technique is driven by the need to investigate the deformation of the aqueous film, as it is squeezed from between the surfaces, under different conditions. Deformation occurring at the fluid/aqueous interface is observed using Fringes of Equal Chromatic Order (FECO) interferometry. A discussion of the technique, its application to film thinning and drainage, and video footage of the interference fringes recorded during the drainage process will be presented.

"Electron Momentum Spectroscopy of Solids"

by Shane Canney of the Department of Physics, Flinders University of South Australia

Electron momentum spectroscopy (EMS) is an experimental technique which enables the direct measurement of the electronic structure of materials. EMS measures the energy-momentum density, which is simply the probability of finding an electron with a particular binding energy and momentum in the system being studied. The results of EMS experiments carried out on aluminium, aluminium oxide and graphite will be presented. These examples illustrate very clearly the detailed information that is obtained regarding the electronic structure of materials using electron momentum spectroscopy.