The primary techniques used in our laboratory are infrared and far infrared spectroscopy. Advances in far infrared spectroscopy made in our laboratory have allowed us to study increasingly more complex and interesting systems. Recently, my students and I have developed a new technique to study the far infrared spectra of ultra-thin inorganic and organic films: Far Infrared Reflection Absorption Spectroscopy or FIRRAS. Currently, this new technique allows us to study films as thin as 50Å. A long range goal is to extend the application of the spectrometer to surface physics phenomena such as surface phonons and the effects of adsorbed molecules.
The study of amorphous ferroelectrics illustrates the relationships between the structure of a material and its solid state properties. The effects of disorder on structural phase transitions is a problem which has interested physicists for many years. Past efforts to examine this problem have been hampered by the lack of an experimental system which allows for the creation of amorphous (non-crystalline) samples of sufficient size to study with far infrared spectroscopic techniques. By using sol-gel techniques we can prepare thin films of the perovskites that in bulk crystalline form undergo a structural phase transition into a ferroelectric state. This preparation technique and the FIRRAS spectrometer provide the first look at the lattice dynamics of amorphous ferroelectric materials. Far infrared spectra taken as a function of temperature from cryogenic temperatures to above the normal ferroelectric to paraelectric phase transition temperatures will provide information on the behavior of the crystal lattice and the dynamics which drive the phase transition. By annealing the films, we will produce films of increasing levels of crystallinity. This will allow us to determine the effects of long range order (crystallinity) on the phase transition. By examining films of several related materials and varying levels of order we should be able to gain quantitative insight on the importance of long range order in mean field phase transitions.
Other projects in progress in our laboratory include study of the dynamics
of model lipid bi-layer membranes, lattice dynamics in aerogels, and far
infrared spectroscopy of magnetic thin films.
" Nothing has such power to broaden the mind as the ability to investigate systematically and truly all that comes under thy observation."Recently I was co-PI of an NSF funded project to re-invent the way in which college physics is taught. Our new course, Physics 7ABC is structured to be more student centered. Following constructivist principles, lecture has been reduced to once per week with the students working in small groups for two 2.5 hour discussion/laboratory meetings per week. A more complete description of the new course and the on-line Learning Resource are available.
-- Marcus Aurelius
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