报告摘要：The world demand for energy is projected to more than double by 2050. Finding sufficient supplies of energy is one of our most daunting challenges. The key in converting energy from one form to another, for example, to utilize energy from sun light and waste heat, is to increase the energy conversion efficiency and reduce the cost/watt of energy conversion. Recently, there are significant progresses in energy conversion research, including converting heat to electricity (thermoelectricity), and converting solar energy to electricity. These new advances are largely resulted from discoveries in nanoscience, nanotechnology, and many unique properties of nanomaterials.

In our laboratory, we carry out energy transfer studies on the critical issues in energy conversion processes. We have developed a laser-based coherent phonon spectroscopy technique to investigate phonon vibration (atomic motion) that determines the energy transfer process. This technique has femtosecond (10^-15 s) time resolution, capable of measuring atomic vibrations which typically have oscillation periods of the order of hundreds of nanoseconds. We work with companies such as General Motors, who is investigating using thermoelectric materials for converting waste heat from automobile exhaust to electricity. With our new experimental techniques, it will be possible to investigate detailed energy conversion and transport processes that will help to design efficient nanoscale energy conversion materials.

报告人简历: Xianfan Xu is a Professor of Mechanical Engineering at Purdue University, and also holds a courtesy appointment as a Professor of Electrical and Computer Engineering at Purdue University. He obtained his M.S. (1991) and Ph.D. (1994) degrees in Mechanical Engineering from the University of California, Berkeley. He joined the School of Mechanical Engineering as an Assistant Professor in 1994, and was promoted to Associate and Full Professor in 2000 and 2004. His current research is on laser-based micro and nano engineering, and the transport phenomena involved in these processes. He is the recipient of the National Science Foundation Faculty CAREER Award (1996) and the Office of Naval Research Young Investigator Award (2000). He was elected as a Fellow of the American Society of Mechanical Engineers in 2006.