IMR: Development of an Acoustic Phonon Spectroscopy System for Materials Research, Education and Outreach

IMR：开发用于材料研究、教育和推广的声学声子光谱系统

• 批准号: 0414895
• 负责人: Keith Nelson
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0414895&HistoricalAwards=false
• 关键词: IMR; Development; Acoustic; Phonon; Spectroscopy

Instrumentation will be developed to permit optical generation and time-resolved measurement of coherent acoustic waves at nearly all wavelengths that propagate through most materials. This extraordinary range will permit tabletop experimental study of structural disorder on the same range of length scales, from nearly 1 millimeter, i.e. clearly macroscopic, to as short as 10 nanometers. It also will provide direct experimental access to dynamical changes in structure that occur over a similarly wide range of time scales, from faster than 1 picosecond to many microseconds, given by the acoustic frequency range of roughly 10 MHz - 500 GHz to which access will be gained. This unique materials research capability will be used for fundamental study of complex liquids, amorphous solids, and partially disordered crystals whose key properties are mediated by structural variation on these length and time scales. The instrumentation also will be used for characterization of advanced structures including thin films and multilayer assemblies of interest in microelectronics and many other applications. The instrumentation will provide access to coherent, narrowband acoustic phonons across most of the Brillouin zone in bulk and thin film materials. Non-Technical Summary Sound waves with wavelengths of meters or millimeters are commonly used to probe structures of comparable size, such as features within the earth's mantle, two-by-four beams behind drywall, or fingers and toes (and their motions) inside the womb. The same principles of ultrasonic imaging and probing can apply to much smaller length scales as well, and there are plenty of micrometer and nanometer size structures that need characterization. These include multilayer thin films in microelectronics devices; nanospheres, nanorods, and other structures fabricated for nanotechnology; the constituents of heterogeneous materials like alloys, suspensions, and gels; and even transient irregularities that form during natural fluctuations or flow in viscous liquids, polymers, and biological fluids. But generating acoustic waves with such short wavelengths, directing them along or through the material of interest, and then detecting them often present daunting challenges. In recent years, novel methods have been developed through which finely tailored laser pulses may be used to generate and detect acoustic waves with specified wavelengths or frequencies. In some cases, a "comb" of laser light is used to imprint the acoustic wave pattern directly onto the material of interest, just as a real comb that suddenly, gently touches a water surface might generate acoustic waves whose wavelength matches the comb spacing (except that the laser light fringes are only microns apart!). In other situations, a timed sequence of laser pulses is used to launch an acoustic wave into a material, just like sequential taps on the side of an aquarium might send acoustic waves into the water within it (except that the light pulses are only picoseconds, i.e. 10X( -12) seconds, apart!). The acoustic waves are not only generated but also detected optically, so no mechanical contact with the sample is needed. These methods have been used to measure nanometer thicknesses of film layers and lateral dimensions of tiny features, transient evolution of viscoelastic fluctuations that govern polymer processing or biological system responses, and a host of other small structures and their dynamics. In this project, equipment will be developed that will permit optical generation and detection of acoustic waves with essentially all possible wavelengths and frequencies that can propagate within a wide range of materials and structural elements. The equipment will be designed to make these measurements not only possible but robust, such that they can be made by high school students in an outreach lab as well as by Ph.D. science and engineering students. In this manner, a new window into microscale and nanoscale structure and behavior will be made widely available.

将开发仪器，以允许在几乎所有通过大多数材料传播的波长下对相干声波的光学产生和时间分辨测量。这个非凡的范围将允许在相同长度范围内的结构障碍的桌面实验研究，从近1毫米，即明显的宏观，到短达10纳米。它还将提供直接实验访问结构的动态变化，该结构发生在类似的时间尺度上发生，从比1 picsecond到许多微秒，由大约10 MHz -500 GHz的声学频率范围给出，访问将为10 MHz -500 GHz。获得。这种独特的材料研究能力将用于对复杂液体，无定形固体和部分无序晶体的基本研究，其关键特性是由这些长度和时间尺度上的结构变化介导的。该仪器还将用于表征高级结构，包括薄膜和多层化的多层组件和许多其他应用。该仪器将在大部分散装和薄膜材料中提供在大多数布里鲁因区域的连贯的窄带声音子。 具有波长米或毫米的非技术摘要声波通常用于探测可比尺寸的结构，例如地球地幔内的特征，在干墙后的两乘四束，手指和脚趾（及其动作）（及其运动）（及其运动）子宫。超声成像和探测的相同原理也可以适用于较小的长度尺度，并且需要大量的微米和纳米尺寸结构需要表征。这些包括微电子设备中的多层薄膜；纳米球，纳米棒和其他用于纳米技术的结构；诸如合金，悬浮液和凝胶等异质材料的成分；甚至在粘性液体，聚合物和生物流体中自然波动或流动过程中形成的瞬时不规则性。但是，以如此短的波长产生声波，将其引导或通过感兴趣的材料引导，然后检测到它们通常会带来艰巨的挑战。近年来，已经开发出新的方法，通过该方法可以使用精细的激光脉冲来生成和检测具有指定波长或频率的声波。在某些情况下，激光光的“梳子”用于将声波模式直接印在感兴趣的材料上，就像一种真实的梳子突然之间一样，轻轻接触水面可能会产生声波，其波长与梳子间距相匹配（除了激光浅条纹仅是微小的！）。在其他情况下，使用激光脉冲的定时序列用于将声波发射到一种材料中，就像水族馆侧面的顺序水龙头一样，可能会将声波发送到其中的水中（除了光脉冲仅是picseconds，仅是picseconds，，即10x（-12）秒，分开！）。声波不仅是产生的，而且是光学检测的，因此不需要与样品的机械接触。这些方法已用于测量薄膜层的纳米厚度和微小特征的横向尺寸，粘弹性波动的瞬时演化，这些波动控制聚合物处理或生物系统响应，以及许多其他小型结构及其动力学。在该项目中，将开发设备，该设备将允许具有基本所有可能的波长和频率的声波的光学生成和检测，这些波长和频率可以在广泛的材料和结构元素中传播。该设备的设计不仅使这些测量不仅成为可能，而且可以使这些测量值稳健，以便可以在外展实验室和博士学位的高中生中制作这些测量。科学与工程专业的学生。以这种方式，将广泛使用微观和纳米级结构和行为的新窗口。