Time Resolved Spectroscopy of Complex Materials

9710140 Nelson本建议的目的是对非晶和部分无序材料的动力学和结构演变有一个改进的基本理解。将研究皮秒到毫秒范围内的过冷液体密度动力学，以及过冷液体行为的模式耦合理论预测。线性和（主要是）非线性晶格动力学晶体的结构相变将被研究，以阐明非调和晶体势能面，决定相变机制以及在短激光脉冲影响下的相变动力学。此外，还将利用激光产生的声波对薄膜结构进行测量，以系统地研究粘附性，并开发一种新型的图案薄膜和薄膜-衬底组件的光声成像，如用于微电子学。了解冷凝材料，如玻璃成型液体和具有粘性液体客体的溶胶-凝胶玻璃，对于涉及依赖于大块和薄膜材料应用的各种技术进步的行业至关重要。例如，该项目将开发新技术，首次全面表征高空间分辨率薄膜衬底结构中的粘附力学，研究短激光脉冲影响下的半导体跃迁，以及玻璃成型液体的密度动力学，这将允许对理论预测进行更完整的测试，并为理论发展提供额外的指导。

9710140 Nelson The aim of this proposal is to achieve an improved fundamental understanding of the dynamical and structural evolution of amorphous and partially disordered materials. Density dynamics of super cooled liquids in the picosecond through millisecond range will be examined, together with the mode-coupling theoretical predictions of supercooled liquid behavior. Linear and (primarily) nonlinear lattice dynamics in crystals near structural phase transitions will be studied to elucidate anharmonic crystalline potential energy surfaces that dictate phase transition mechanisms as well as the dynamics of phase transitions under the influence of short laser pulses. Measurements will also be conducted on thin film structures using laser generated acoustic waves to carry out a systematic study of adhesion, and to develop a new kind of photoacoustic imaging of patterned films and film-substrate assemblies such as those used in microelectronics. %%% An understanding of condensed materials such as glass forming liquids and sol-gel glasses with viscous liquid guests are of tremendous importance to industries involved with the advancement of various technologies dependent on both bulk and thin film materials applications. For example, this project will develop new techniques that will allow for the first-time a thorough characterization of adhesion mechanics in highly spatially resolved film substrate structures, the study of semiconductor transitions under the influence of short laser pulses, and density dynamics in glass forming liquids that will allow more complete testing of theoretical predictions and additional guidance for theoretical development.