RUI: Photon Impact Ionization of Fullerene and Endofullerene Molecules: Cross Sections, Resonances, and Time-Delays

RUI：富勒烯和内富勒烯分子的光子碰撞电离：横截面、共振和时间延迟

• 批准号: 1413799
• 负责人: HIMADRI CHAKRABORTY
• 金额: $ 16.5万
• 依托单位: Northwest Missouri State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1413799&HistoricalAwards=false
• 关键词: RUI; Photon; Impact; Ionization; Fullerene

The encapsulation of an atom or a cluster of atoms, or even a smaller fullerene (buckyball made of carbon atoms) inside a larger fullerene cage offers a unique molecular-level laboratory in which to examine the behavior of the guest system in sub-nanometer to nanometer (1 billionth of a meter) size confinements. Studies of these so called endofullerenes can not only lead to intriguing effects at the atomic scale but also can probe processes within the nanometric space that can be accessed by the current technology. In fact, the endofullerenes hold the promise of exciting applications in areas including quantum computations, superconductivity, biomedical fields, drug delivery research, magnetic resonance imaging, and organic photovoltaic devices. Further, the discovery of endofullerenes in extraterrestrial environments indicates their astrophysical relevance. Hence, understanding the influence of the confining fullerene cage on the behavior of the confined species, and vice versa, are matters of great scientific interest. For atoms confined in a fullerene, recent studies have predicted huge enhancements and alterations in the atom's response to radiation. However, it is not known how the process will evolve if instead a cluster of metal atoms or a smaller fullerene is confined. By examining couplings between such captive-captor pairs, researchers will be able to uncover fundamental effects, thereby substantially adding to the current knowledge. With capabilities of precision measurements being available, such findings shall motivate experiments involving cluster-doped endofullerenes. Furthermore, advancements in technology for generating extremely short attosecond (1 billion billionth of a second) laser pulses enable study of the light-matter interaction time with unprecedented precision. Results from this program produced the best agreement so far with the argon atom's time-delay measurements. Encouraged by this result, attosecond response studies of endofullerenes will be initiated. The outcome may bridge the gap between atto- and nano-sciences to establish a new domain of research in 'atto-nano-science'. Finally, another planned research area will focus on processes wherein a light-driven stimulation is caused at one location inside the compound which subsequently de-stimulates to transfer energy off-site to cause a dramatic response in a new location. The current program will access processes in endofullerenes where such local stimulations may cause a global response. This is similar to an antenna-receiver pair at the molecular scale where the antenna couples to the incoming light and transfers energy globally to enhance the efficiency of the ultimate output by enabling the antenna to also contribute to the process in sync with the receiver. The effect and related knowledge may have significant utilization in nanoscale antenna technology. This project involves the theoretical study of the response of neutral and ionic endofullerenes to an external photon. Photoelectron cross sections, angular distributions, Wigner-Smith time delays, and intercoulombic decay (ICD) resonances for both pure and hybrid levels of the compound will be calculated. This will help to understand better: (i) The many-body interactions that determine the absorption, temporal and resonant-decay properties at low plasmonic energies; and (ii) The diffraction-type oscillations due to multipath interferences between electron waves from various sites of the compound. Several areas will be studied. First, for atoms confined in C60, recent studies predicted huge enhancements in the atomic photoionization over the C60 plasmon resonance energy region. However, it is not entirely known how this coupling will evolve if instead a metal cluster or a smaller fullerene is confined, since these systems can excite their own plasmons. It is expected that by examining couplings between the plasmon-active captive-captor pair novel effects will be discovered, thereby substantially adding to the current knowledge. With recent capabilities of precision measurements such findings shall motivate experiments involving cluster-doped or onion-type endofullerenes. Second, for a confined atom the photo-liberation of atomic inner-electrons involves reflection off the fullerene shell. For the atom-fullerene hybrid-levels emissions from both the atomic and the fullerene sites occur. The quantum multipath interference between these modes of emissions carries a wealth of information on the geometry of the compound. Replacing the inner atom by a cluster or a fullerene will further compound this interference effect, producing far richer structures in photoionization cross section that can be diagnosed with our recently established Fourier photospectroscopy methods, thereby, significantly advancing scientific knowledge. Next the intercoulombic decay (ICD) process is a naturally abundant nonradiative relaxation pathway of a vacancy in a cluster and a topic of intense contemporary interest. The precursor excitation to form this vacancy can be accomplished by promoting an inner shell electron to an excited state by the photon or charged particle impact. Endofullerenes, being rotational analogues of asymmetric dimers of two concentric and unequal systems, can induce novel ICD processes. Research results in this topic can, therefore, generate significant experimental impetus, besides discovering fundamental effects. Finally, advancements in technology for generating attosecond laser pulses enable study of the light-matter interaction with unprecedented precision by pump-probe experiments. Attosecond photoemission studies of endofullerenes have been initiated. The outcome may bridge the gap between atto- and nano-sciences to establish a new domain of research in 'atto-nano-science'.

在较大的富勒烯笼中的原子或一个原子簇，甚至是较小的富勒烯（由碳原子制成）的封装，提供了一个独特的分子级实验室，可以在其中检查子纳米计中客人系统的行为至纳米（十亿分之一）尺寸限制。 对这些所谓的内氟烯的研究不仅可以在原子量表上产生有趣的效果，而且可以探测当前技术可以访问的纳米空间内的过程。 实际上，Endofullerenes在包括量子计算，超导性，生物医学领域，药物递送研究，磁共振成像和有机光伏设备在内的区域中具有令人兴奋的应用的希望。此外，在外星环境中发现内叶烯烯表明它们的天体物理相关性。 因此，理解限制富勒烯笼对被限制物种行为的影响，反之亦然，是极大的科学利益的问题。对于富勒烯中限制的原子，最近的研究预测了原子对辐射的反应的巨大增强和改变。但是，如果将一组金属原子或较小的富勒烯限制在相反的情况下，尚不清楚该过程将如何发展。通过检查此类圈养的冠军对之间的耦合，研究人员将能够发现基本效果，从而实质上增加了当前知识。借助可用的精确测量功能，此类发现应激发涉及掺杂簇的内叶烯的实验。此外，在产生极短的Attosecond（一秒钟10亿亿）的技术方面的进步激光脉冲可以研究以前所未有的精度研究光 - 物质的相互作用时间。迄今为止，该计划的结果与Argon Atom的时间延迟测量达成了最佳协议。在这种结果的鼓励下，将启动对内列烯的Attsond响应研究。结果可能会弥合Atto-和纳米划分之间的差距，以建立“ Atto-Nano-Science”研究的新研究领域。最后，另一个计划的研究区域将重点放在过程中，其中在化合物内的一个位置引起轻驱动刺激，随后将其去刺激以将能量转移到现场，以在新位置引起剧烈的响应。当前的程序将访问此类局部刺激可能导致全球响应的Endofullerenes的过程。这类似于在分子尺度上的天线接收器对，在分子尺度上，天线伴侣伴侣向传入的光线并在全球范围内传输能量，从而通过使天线也能够与接收方同步促进最终输出的效率。效果和相关知识可能在纳米级天线技术中具有大量利用。 该项目涉及中性和离子内叶烯对外部光子的反应的理论研究。将计算光电电子横截面，角度分布，Wigner-Smith时间延迟以及该化合物的纯和混合水平的鸡际衰变（ICD）共振。这将有助于更好地理解：（i）在低等离子能量下确定吸收，时间和谐振特性的多体相互作用； （ii）由于来自化合物的各个位点的电子波之间的多径干扰引起的衍射型振荡。将研究几个区域。首先，对于限制在C60中的原子，最近的研究预测了C60等离子体共振能量区域的原子光电离能力巨大。但是，如果将金属簇或较小的富勒烯限制为限制，则并不完全知道这种耦合将如何发展，因为这些系统可以激发自己的等离子。可以预期，通过检查等离子活性圈养对手对之间的耦合，将发现新颖的效果，从而实质上增加了当前知识。凭借最新的精确测量能力，这些发现应激发涉及掺杂或洋葱型内叶烯的实验。其次，对于限制原子，原子内电原子的光启动涉及富勒烯壳的反射。对于原子 - 富勒烯杂交水平的排放量，来自原子和富勒烯地点的排放量都发生。这些排放模式之间的量子多径干扰具有有关该化合物几何形状的大量信息。用簇或富勒烯代替内部原子将进一步加剧这种干扰效果，从而在光电离横截面中产生更丰富的结构，可以诊断出我们最近建立的傅立叶照片光谱方法，从而显着提高了科学知识。接下来，冠状动脉衰减（ICD）过程是一个自然丰富的非赋权放松途径，在集群中空缺和一个强烈的当代兴趣主题。可以通过通过光子或带电的粒子撞击将内壳电子推广到激发态来实现的前体激发。 Endofullerenes是两个同心系统不对称二聚体的旋转类似物，可以诱导新的ICD过程。因此，除了发现基本效果外，该主题的研究结果还可以产生重大的实验动力。最后，通过泵探针实验进行了前所未有的精度，可以研究产生Attsond激光脉冲的技术进步。启动了内叶烯的attosent光发作研究。结果可能会弥合Atto-和纳米划分之间的差距，以建立“ Atto-Nano-Science”研究的新研究领域。