Super Resolution THz Imaging of Nanostructures

纳米结构的超分辨率太赫兹成像

• 批准号: 1902403
• 负责人: Gregory Hartland
• 金额: $ 42.08万
• 依托单位: University of Notre Dame
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1902403&HistoricalAwards=false
• 关键词: Super; Resolution; THz; Imaging; Nanostructures

Recently invented super-resolution microscopes are having a large impact on the fields of chemistry, biology, and materials science, due to these microscopes providing previously unheard-of images of objects with dimensions approaching that of molecules. However, important chemical and electrical features of conducting and semiconducting nanomaterials cannot be visualized with existing microscopes, because of energy limitations associated with the light used. With support from the Chemical Measurement and Imaging Program, and partial co-funding from the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry and the Electronic and Photonic Materials Program in the Division of Materials Research of the National Science Foundation, Professor Hartland and his group at the University of Notre Dame are developing a new super-resolution microscope for recording images of materials through a novel approach that takes advantage of low-energy light in the terahertz region of the electromagnetic spectrum. The smallest sized feature the terahertz microscope can resolve is a few hundred nanometers, which is 100 to 1000 times better than previously possible. The newly unleashed power of the terahertz microscope is being used by Professor Hartland and graduate and undergraduate students to study materials that hold promise for more efficient solar cells and nanomaterials that may one day be used in ultra-sensitive chemical detection systems. It is anticipated that the new terahertz microscope will be adopted by researchers who study biologicals, superconductors, and integrated circuit devices, and ways to identify trace amounts of chemicals, such as residues from explosives. Efforts go beyond training of students at the university level, with a major focus being participation of high school students and teachers recruited from the Elkhart Community Schools, a local school district with students who come from highly diverse socioeconomic backgrounds. Sustained impact of the Elkhart School collaboration is being achieved by the high school teachers receiving graduate credits for their summer research activities. This program leads to teacher participants being able to teach Indiana University dual-enrollment courses, thereby broadening the educational opportunities provided by the Elkhart Community Schools.Terahertz spectroscopy is widely used to examine semiconductors and plastics; however, currently existing terahertz microscopes have very low spatial resolution due to the diffraction limit. In a traditional terahertz microscope, the minimum feature size that can be resolved is determined by the wavelength of the impinging light divided by two, which is approximately 50 micrometers in the terahertz region. The unique approach taken by the Hartland group is based on a tightly focused visible probe beam that monitors absorption of a terahertz pump beam through the photothermal effect. The resolution in these experiments is dictated by the visible probe beam, and, as a result, is several hundred nanometers rather than tens of micrometers. The photothermal terahertz microscope is being used to examine photo-conductivity and the terahertz spectroscopy of thin films and individual nanostructures. These experiments are providing new information about the spatial distribution and motion of photo-excited charge carriers in the different structures, and the decay pathways for the charge carriers. This information is important for developing materials for photo-voltaic solar cells. Terahertz spectroscopy experiments are also being performed on the low frequency resonances of nanomaterials, which is generating new information about how these materials interact with their environment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

最近发明的超分辨率显微镜对化学、生物学和材料科学领域产生了巨大影响，因为这些显微镜提供了以前闻所未闻的尺寸接近分子的物体图像。然而，由于与所用光相关的能量限制，现有的显微镜无法观察到导电和半导体纳米材料的重要化学和电学特征。在美国国家科学基金会化学测量和成像项目的支持下，以及美国国家科学基金会化学部高分子、超分子和纳米化学项目以及材料研究部电子和光子材料项目的部分共同资助下，Hartland教授和他在圣母大学的团队正在开发一种新型超分辨率显微镜，通过一种利用电磁波谱太赫兹区域低能光的新方法来记录材料图像。太赫兹显微镜可以分辨的最小尺寸特征是几百纳米，比以前的分辨率提高了 100 到 1000 倍。哈特兰教授以及研究生和本科生正在利用太赫兹显微镜新释放的力量来研究有望生产更高效太阳能电池和纳米材料的材料，这些材料有一天可能会用于超灵敏化学检测系统。预计新型太赫兹显微镜将被研究生物、超导体和集成电路器件以及识别微量化学物质（例如爆炸物残留物）的方法的研究人员采用。这些努力不仅限于对大学层面的学生进行培训，重点是从埃尔克哈特社区学校招募的高中生和教师的参与，埃尔克哈特社区学校是当地的一个学区，学生来自高度多样化的社会经济背景。埃尔克哈特学校合作的持续影响是通过高中教师的暑期研究活动获得研究生学分来实现的。该计划使教师参与者能够教授印第安纳大学双注册课程，从而扩大了埃尔克哈特社区学校提供的教育机会。太赫兹光谱广泛用于检查半导体和塑料；然而，由于衍射极限，目前现有的太赫兹显微镜的空间分辨率非常低。在传统的太赫兹显微镜中，可分辨的最小特征尺寸由入射光的波长除以二决定，在太赫兹区域约为 50 微米。 Hartland 小组采用的独特方法基于紧密聚焦的可见探测光束，通过光热效应监测太赫兹泵浦光束的吸收。这些实验中的分辨率由可见探测光束决定，因此为数百纳米而不是数十微米。光热太赫兹显微镜用于检查薄膜和单个纳米结构的光电导性和太赫兹光谱。这些实验提供了有关不同结构中光激发载流子的空间分布和运动以及载流子衰变路径的新信息。该信息对于开发光伏太阳能电池材料非常重要。太赫兹光谱实验也在纳米材料的低频共振上进行，这产生了有关这些材料如何与其环境相互作用的新信息。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和评估进行评估，被认为值得支持。更广泛的影响审查标准。

项目成果

Photothermal heterodyne imaging of micron-sized objects

微米级物体的光热外差成像

• DOI: 10.1364/ao.501222
• 发表时间: 2023-11
• 期刊: Applied Optics
• 影响因子: 1.9
• 作者: Bhandari, Janak;Brown, Brendan S.;Huffman, John A.;Hartland, Gregory V.
• 通讯作者: Hartland, Gregory V.

Hyperspectral and Nanosecond Temporal Resolution Widefield Infrared Photothermal Heterodyne Imaging

高光谱和纳秒时间分辨率宽场红外光热外差成像

• DOI: 10.1021/acsphotonics.3c00559
• 发表时间: 2023-08
• 期刊: ACS Photonics
• 影响因子: 7
• 作者: Kniazev, Kirill;Zaitsev, Evgenii;Zhang, Shubin;Ding, Yang;Ngo, Loc;Zhang, Zhuoming;Hartland, Gregory V.;Kuno, Masaru
• 通讯作者: Kuno, Masaru

Influence of thermal diffusion on the spatial resolution of photothermal microscopy

热扩散对光热显微镜空间分辨率的影响

• DOI: 10.1117/12.2607795
• 发表时间: 2022-03
• 期刊: Nanoscale and Quantum Materials: From Synthesis and Laser Processing to Applications
• 作者: Brown, Brendan S.;Hartland, Gregory V.
• 通讯作者: Hartland, Gregory V.

Approaches to mid-infrared, super-resolution imaging and spectroscopy

中红外、超分辨率成像和光谱学方法

• DOI: 10.1039/c9cp05815j
• 发表时间: 2020-02
• 期刊: Physical Chemistry Chemical Physics
• 影响因子: 3.3
• 作者: Pavlovetc, Ilia M.;Aleshire, Kyle;Hartland, Gregory V.;Kuno, Masaru
• 通讯作者: Kuno, Masaru

Quantitative infrared photothermal microscopy

定量红外光热显微镜

• DOI: 10.1117/12.2545159
• 发表时间: 2020-02
• 期刊: Single Molecule Spectroscopy and Super-resolution Imaging XIII
• 作者: Pavlovetc, Ilia M.;Podshivaylov, Eduard A.;Frantsuzov, Pavel A.;Hartland, Gregory V.;Kuno, Masaru K.
• 通讯作者: Kuno, Masaru K.