Tailored Metal Nanostructures: Beyond Plasmon Excitation

纳米材料的功能是通过材料的精确合成和颗粒表面的控制来定制的。在即将到来的拨款期内，我的小组将集中精力研究两类新的纳米结构；1)原子精确的簇，2)纳米激光器。***1)我（和其他几个小组）已经合成了银和金的金属粒子，其精度精确到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“簇”。例如，迄今为止实现的最稳定的簇之一是由25个金原子和18个硫醇配体组成的，分子式为Au25(SR)18。这些团簇不再表现得像纳米颗粒，而表现得更像分子，具有HOMO-LUMO电子跃迁和荧光，这是任何其他尺寸的金属颗粒都没有观察到的特性。由于其独特的光学特性，簇被广泛应用于光伏（太阳能电池）、光催化、传感器和生物成像应用（如成像癌细胞）等领域。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内，我们将对金属团簇的光学性质有一个急需的了解。我们将利用这些信息来设计具有所需光学性质的新团簇。光谱学技术对于理解这些材料的光学特性至关重要。***2)金属纳米颗粒表面可产生相干光场。如果它们能与周围的介质耦合，就能像激光器一样工作。我们最近利用这一点制造了迄今为止最小的纳米激光器，直径约为30纳米。从最初的发现中产生了重要的问题。例如，有一个基本的问题是纳米激光器是否可能被电泵浦（类似于激光笔的工作原理）。***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、激光和纳米等离子体学的新材料，电子芯片制造和生物医学材料的光刻。在即将到来的拨款期间，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，同时作为激光，这是以前从未做过的。这项研究将使我们能够回答围绕这一新兴领域的一些基本问题，并设计出可用于光学和声学的结构。***通过具有挑战性的研究、小组演讲和参加会议，HQP将获得多样化的专业技能、批判性思维、口头和书面沟通技巧。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强大的根基。* * * * *

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.*** **