Tailored Metal Nanostructures: Beyond Plasmon Excitation

纳米材料的功能是通过精确合成材料和控制颗粒表面来定制的。在即将到来的拨款期间，我的团队将专注于两类新的纳米结构：1)原子精确的团簇，2)纳米激光。*1)我(和其他几个团队)已经合成了银和金的金属颗粒，其精确度足以控制金属原子和配体的确切数量。这些原子上精确的粒子被称为团簇。例如，到目前为止实现的最稳定的团簇之一是由25个金原子和18个硫醇配体组成，分子式为AU25(SR)18。这些团簇的行为不再像纳米粒子，而是更像分子，具有HOMO-LUMO电子跃迁和显示荧光，这是任何其他尺寸的金属颗粒都没有观察到的特性。*由于其独特的光学性质，团簇已被提出在光伏(太阳能电池)、光催化、传感器和成像癌细胞等生物成像应用领域。在所有这些应用中，光学性质决定了团簇的功能。在即将到来的资助期间，我们将对金属团簇的光学性质有一个非常必要的了解。我们将在设计具有指定所需光学性质的组成的新的团簇时使用这些信息。光谱学技术将是理解这些材料的光学性质的关键。*2)在金属纳米颗粒的表面可以产生相干光场。如果它们能与周围的介质耦合，就可以使它们充当激光。我们最近利用这一点制造了有史以来最小的纳米激光器，直径约为30纳米。从最初的发现中出现了一些重要的问题。例如，纳米激光器是否可能被电泵浦(类似于激光指示器的工作原理)是一个基本问题。*在过去十年的大部分时间里，我开发了合成具有所需性能的金属纳米材料的方法，这些方法导致了电子、光子学、激光和纳米等离子、电子芯片制造的光刻和生物医学材料的新材料。在即将到来的资助期间，我们将设计新的金属复合纳米激光器，并使用光谱技术来跟踪等离子激元的激发，同时充当激光器，这是以前从未做过的。这项研究将使我们能够回答这个新兴领域的一些基本问题，并设计可用于光学和声学的结构。*通过具有挑战性的研究、小组报告和出席会议，HQP将获得不同的技能集，包括学科专业知识、批判性思维以及口头和书面沟通技能。HQP将成为全球物理化学家专业网络的一部分，在加拿大学术界有着深厚的根基。

The functionality of nanomaterials is tailored through precise synthesis of the material and control of particle surfaces. During the forthcoming grant period, my group will focus efforts on two new classes of nanostructures; 1) atomically precise clusters, and 2) nanolasers.***1) I (and several other groups) have synthesized metal particles of Ag and Au with precision refined enough to control the exact number of metal atoms and ligands. These atomically precise particles are called clusters'. For example, one of the most stable clusters realized to date is made of 25 gold atoms and 18 thiol ligands, with molecular formula Au25(SR)18. These clusters no longer behave like nanoparticles, but behave more like molecules, with HOMO-LUMO electronic transitions and display fluorescence, a property not observed for any other size of metal particles.***Owing to their unique optical properties, clusters have been proposed in fields as diverse as photovoltaics (solar cells), photocatalysis, sensors and bioimaging applications like imaging cancer cells. In all of these applications, the optical properties dictate the function of the clusters. During the forthcoming grant period, we will gain a much-needed understanding of the optical properties of metal clusters. We will use the information in the design of new clusters with compositions that dictate the desired optical properties. Spectroscopy techniques will be essential in understanding the optical properties of these materials.***2) Coherent optical fields can be generated at the surface of metal nanoparticles. They can be made to act as lasers if they can couple with the surrounding medium. We recently exploited this to make the smallest nanolasers ever made, having a diameter of ~30 nm. Important questions have arisen from the initial discoveries. For example, there are fundamental questions of whether or not it is possible for nanolasers to be electrically pumped (similar to how a laser pointer works).***Over most of the last decade I have developed methods for synthesizing metal nanomaterials with desired properties that have lead to new materials for electronics, photonics, lasers and nanoplasmonics, lithography for electronic chip fabrication and biomedical materials. During the coming grant period we will engineer new metal composite nanolasers and use spectroscopic techniques to follow plasmon excitation while acting as a laser, which has never been done before. This research will allow us to answer some of the fundamental questions around this emerging field and to design structures that can be used in optics and phonics.***Through challenging research, group presentations, and conference attendance, HQP will gain a diverse skill set of subject expertise, critical thinking, and oral and written communication skills. HQP will become part of a global professional network of physical chemists, with strong roots in Canadian academia.*** **