Ultrasonic Measurements Near Transitions

Garland博士将运用实验方法，在他的实验室中改进，研究结构玻璃的形成和行为以及相应的相，低温物理和化学的重要研究领域。超声波测量提供了一种很好的方法，通过提供表征玻璃“冻结”温度和监测兆赫兹频率范围内的冷冻前动态的重要工具，增强了对这些具有挑战性问题的基本理解。此外，这些实验测量为检验纯流体中的现代临界动力学理论提供了必要的数据，并为新理论的发展指明了方向。超声波研究也很有优势，因为系统的静态和动态响应可以通过同时测量声波的速度和衰减作为频率的函数来确定。这些测量将作为温度和组成的函数来进行：1)碱氰化物结构玻璃，2)偶极铁电/反铁电结构玻璃，以及3)具有不相称相的晶体。

Dr. Garland will apply experimental methods, refined in his laboratory, to study in formation and behavior of structural glasses and the commensurate phases, important research areas in low temperature physics and chemistry. Ultrasonic measurements provide an excellent method to enhance the basic understanding of these challenging problems by providing an important tool for characterizing the glass "freezing" temperature and for monitoring prefreezing dynamics in the megahertz frequency range. In addition, these experimental measurements provide the data essential to testing modern theories of critical dynamics in pure fluids and to point the directions for the development of new theory. Ultrasonic studies are also advantageous since both the static and dynamic response of a system can be determined from simultaneous measurements of velocity and attenuation of acoustic waves as a function of frequency. Such measurements will be made as a function of temperature and composition in 1) alkali cyanide structural glasses, 2) dipolar ferro/antiferroelectric structural glasses, and 3) crystals exhibiting incommensurate phases.