CAREER: Integrated Research and Education in Nano- and Microscale Photoacoustic and Photothermal Microscopy

CMS 0448796CAREER：纳米和微尺度光声和光热显微镜的综合研究和教育T.W.默里：波士顿大学这个职业项目的主要目标是使微米和纳米尺度上的热和机械性能能够快速、准确地成像，从而有助于提高微米级系统的性能和可靠性，并努力了解和控制纳米级材料的热和机械行为。PI开发了新颖的光声和光热(PA/PT)测量能力，用于在纳米级对表面属性和亚表面缺陷进行非接触和无损成像，并了解测量量与目标材料的热机械属性的关系。探索了一种用于PA/PT成像的高度局域热源和探针的制造技术，目的是将PA/PT显微镜的横向分辨率提高到纳米级。这种新颖的成像方式利用了等离子体共振频率激发的纳米颗粒周围的高吸收和局域场增强，将在寻求在纳米尺度上理解和表征材料行为方面产生广泛的影响。其次，研制了一种高分辨率光声显微系统，该系统采用高频(GHz)调制激发源。通过减少带宽和脉冲编码技术，有望改善脉冲系统的信噪比，从而扩大这种无损检测技术适用的应用范围。本建议的最后重点领域集中在复杂材料系统中激光产生声波和热波的建模，这一领域对于解释这些系统中的热和声信号以及准确地反转这些信号以获得材料性质信息至关重要。研究成果将直接应用于纳米制造：在线监测制造过程以及测量“预制”材料系统的基本性质。该项目支持研究生和本科生研究人员，并在工程科学的广泛领域对这些学生进行培训，包括无损检测、应用光学、弹性波传播和纳米工程学。该职业项目支持新科学家学习经验(LENS)计划的发展和实施，在该计划中，学业困难的7年级和8年级学生来到波士顿大学进行为期一周的演示和问题解决活动。这项计划针对的是科学技能发展的关键时期的学生，旨在减少高中毕业时缺乏基本科学和数学熟练程度的学生人数。为镜头计划开发的多媒体演示文稿被放在网上传播给其他教育工作者，并通过波士顿大学的学习资源网络(Lernet)计划提供给其他外展计划。根据这个项目，国际和平研究所已经安排了一名研究生在劳伦斯·利弗莫尔国家实验室工作一个夏天。这个机会允许学生与LLNL的几位激光超声波专家互动，并拓宽他/她的教育背景。PI在材料力学行为领域开设了一门新的本科课程，其中将讨论材料的无损检测。PI还开发了固体力学实验技术研究生课程的无损检测演示。国际学生联合会担任一个专业学会学生团体的教师顾问，并将在波士顿大学主办未来的地区性学生会议。PI计划邀请当地公司和教育机构的代表向学生讲述NDE的重要性。

CMS 0448796CAREER: Integrated Research and Education in Nano- and Microscale Photoacoustic and Photothermal MicroscopyT.W. Murray: Boston UniversityAbstract The primary objective of this CAREER project is to enable rapid, accurate imaging of thermal and mechanical properties on micrometer and nanometer length scales, thereby contributing to the effort to improve the performance and reliability of micron scale systems and in the effort to understand and control the thermal and mechanical behavior of materials at the nanoscale. The PI develops novel photoacoustic and photothermal (PA/PT) measurement capabilities for the noncontact and nondestructive imaging of surface properties and subsurface defects at the nanoscale, along with an understanding of how the measured quantities relate to the thermo-mechanical properties of the target material. A technique for producing highly localized heat sources and probes for PA/PT imaging is explored, with the goal of pushing the lateral resolution of PA/PT microscopy to the nanoscale regime. This novel imaging modality makes use of the high absorption and local field enhancement around nanoparticles excited at the plasmon resonance frequency, and will have a broad impact in the quest to understand and characterize material behavior at the nanoscale. Next, A high-resolution photoacoustic microscopy system is developed which uses a high-frequency (GHz) modulated excitation source. Improvements in signal to noise ratio over pulsed systems are expected through bandwidth reduction and pulse coding techniques, expanding the range of applications for which this NDE technique is suitable. The final thrust area in this proposal focuses on the modeling of laser generation of acoustic and thermal waves in complex materials systems, an area which is essential for the interpretation of thermal and acoustic signals in these systems, and for accurate inversion of these signals to obtain material property information. The research results will have direct applications in nanofabrication: for online monitoring of the fabrication process as well as in the measurement of the fundamental properties of "as-fabricated" materials systems. This project supports both graduate and undergraduate researchers, and trains these students in a wide cross-section of engineering science that this project draws upon including NDE, applied optics, elastic wave propagation, and nanoscale engineering. This CAREER project supports the development and implementation of the Learning Experiences for New Scientists (LENS) program in which academically at-risk 7th and 8th grade students come to Boston University for a week of hands on demonstrations and problem solving activities. This program targets students at a critical time in the development of science skills, and is aimed at reducing the number of students graduating from high school who lack basic proficiency in science and math. The multi-media presentations developed for the LENS program are placed on the Web to disseminate to other educators, and are made available for other outreach programs through the Learning Resource Network (LERNet) program at Boston University. The PI has arranged for a graduate student to work at Lawrence Livermore National Lab for one summer under this project. This opportunity allows the student to interact with several experts on laser ultrasonics at LLNL, and to broaden his/her educational background. The PI develops a new undergraduate course in the area of mechanical behavior of materials, in which the NDE of materials will be discussed. The PI also develops NDE demonstrations for a graduate course in experimental techniques in solid mechanics. The PI serves as the faculty advisor for a professional society student group, and will host a future regional student conference at BU. The PI plans to invite representatives from local companies and educational institutions to speak to the students about the importance of NDE.