Molecular Spectroscopy of Carbon Nanotubes

该项目的目标是通过研究单壁碳纳米管发现阶段的新现象，通过研究与碳纳米管一维相关的光谱现象的争议和悬而未决的问题，以及通过发展研究碳纳米管的光谱的新能力，在很大程度上促进单壁碳纳米管的光谱研究。其方法是围绕四个主题：1)通过实验解释新发现的与600-1100厘米-1中频范围内的共振拉曼光谱中的组合模相关的异常现象，其中观察到随着激光激发能量的变化而出现新的开/关现象，然后解释新观察到的现象背后的物理原因；2)通过实验研究制定一种策略，以解决对单壁碳纳米管中主要的G带光谱特征的两种看似不同的解释，即这些特征是由于一阶散射过程还是双共振过程。根据这一策略，将为这两个过程的研究创造有利的条件，以便能够定量地研究它们之间的相互关系；3)通过开发自由悬浮的单个单壁纳米管的光谱测量技术，提高单纳米管水平的拉曼光谱测量的信噪比。这项研究有望在实验上解决以前隐藏在噪声中的现象，从而开辟新的研究方向；4)通过对同一纳米管系统地开展单分子拉曼散射和光致发光中观察到的电子态密度奇点之间的关系，开发一种策略。将对两束单壁碳纳米管和单根单壁碳纳米管进行测量。目前，这两种技术给出的结果似乎在已报道的共振能量的值和在恒定直径下观察到的共振能量集合的传播方面都不同。%该项目解决了材料科学中具有高度技术相关性的主题领域的基础研究问题。该计划的一个重要特点是通过在一个具有根本和技术意义的领域培训学生和博士后研究人员，将研究和教育结合起来。该项目通过一个高度协作的前沿研究环境，通过独特的教育体验，帮助学生发展技术、沟通和组织/管理技能。预期这项研究将产生广泛的影响，包括培训该领域的青年男女领导人，通过特邀讲座和出版物广泛传播这项研究的结果，并编写辅导评论文章，将该领域各研究人员的工作相互联系起来，并确定未来重要和有希望的研究领域。首席研究员和她的学生将继续通过面向普通受众的应邀讲座，以及通过为政府、工业实验室、大学和专业协会提供咨询工作，向公众传播纳米科学和纳米技术的进展。*

The objective of this project is to advance the spectroscopy of single wall carbon nanotubes (SWNTs) in a major way by studying new phenomena in their discovery phase, by examining controversial and unresolved issues concerning spectroscopic phenomena associated with the one-dimensionality of carbon nanotubes, and by developing new capabilities for studying the spectroscopy of carbon nanotubes. The approach is to focus on four topics: 1) experimentally elucidate the newly discovered unusual phenomena associated with combination modes in the resonance Raman spectra in the intermediate frequency range of 600-1100 cm-1 where new turn-on/turn-off phenomena are observed, as the laser excitation energy is varied, and then explaining the physics behind the newly observed phenomena; 2) develop a strategy for resolving through experimental investigation of the two seemingly different interpretations for the fundamental mechanism responsible for the dominant G-band spectral features in single wall carbon nanotubes, namely, whether these features are due to first-order scattering processes or to double resonance processes. According to this strategy, conditions favorable for the study of the two processes will be created so that their interrelation can be studied quantitatively; 3) improvement of the signal-to-noise in Raman spectroscopy measurements at the single nanotube level by developing techniques for measuring spectra on freely suspended individual single wall nanotubes. This research is expected to experimentally resolve phenomena that were previously buried in the noise and thus to open up new research directions; 4) develop a strategy for gaining an understanding of the relationship between the singularities in the electronic density of states as observed in single molecule Raman scattering and in photoluminescence, by systematically carrying out the two types of studies on the same individual nanotubes. Measurements on both bundles of SWNTs and on individual SWNTs will be carried out. At present, the two techniques give results that appear to differ regarding both the values of the resonant energies that have been reported and the spread of the ensemble of resonant energies observed at constant diameter.%%% The project addresses basic research issues in a topical area of materials science with high technological relevance. An important feature of the program is the integration of research and education through the training of students and postdoctoral researchers in a fundamentally and technologically significant area. The project assists development of technical, communication, and organizational/management skills in students through unique educational experiences made possible by a highly collaborative forefront research environment. The research is expected to have broad impacts through the training of young men and women leaders in the field, by the wide dissemination of the findings of this research through invited talks and publications, and through the preparation of tutorial review articles to interrelate the work of various researchers in the field, and to identify future research areas of importance and promise. The principal investigator and her students will continue to disseminate advances in nanoscience and nanotechnology to the public through invited talks to general audiences, and through advisory work for the government, industrial laboratories, universities and professional societies.***