RUI: Studies of Single Molecule Vibrational Spectra and Zero Bias Features Using Point-Contact Tunnel Junctions

在这个项目中，一个新的隧道配置将用于研究吸附在金属表面上的分子的振动光谱，并进行实验，以了解零偏置功能（ZBF）的物理起源，这似乎是一个普遍的方面的技术。该技术使用非弹性电子隧穿光谱（IETS）适应于一种新的配置，“自组装隧道结”（SATJ），由两个金属线在一个十字形的几何形状。在SATJ中，稀有气体阻挡膜取代了IETS中通常使用的金属-氧化物-金属结的氧化层。初步实验表明，利用这种技术，可以区分化学吸附在金属电极上的乙炔分子和物理吸附或掺入稀有气体膜中的乙炔分子。 无论隧道势垒膜的组成如何，所有数据都显示了零偏置电压附近的区域，其中结电导显著降低，ZBF。 在该项目中，将进行同位素替代实验，以测量该技术的最终灵敏度。 目标是观察和研究单分子的光谱，以了解吸附和隧穿电子-分子相互作用。 ZBF将作为温度，阻挡膜组合物，电极组合物和不同的结电导的函数进行检查，目的是确定这种知之甚少的效果背后的机制。 这项研究将在一所本科院校进行。 本科生将参加这个项目，并将学习技能的研究领域，这将为他们准备研究生院和未来的就业。%在这个项目中，一种新的方法将被用来研究吸附在金属表面上的分子的化学和物理性质，并确定在这些和其他实验中存在的一种知之甚少的效应，即所谓的零偏置特征（ZBF）。 通过新的实验方法，将测量乙炔和一氧化碳的同位素，以确定该技术的最终灵敏度。 目的是观察和研究单个分子，从而更好地了解分子在表面上的吸附。 为了更好地理解这一现象，将详细研究ZBF的行为。 该项目将在本科院校进行，本科生将参与研究。 因此，他们将获得研究领域的技能，为研究生院的高级培训和未来的就业做好准备。

In this project a new tunneling configuration will be used to study the vibrational spectra of molecules adsorbed on metal surfaces and to perform experiments to understand the physical origin of the zero-bias feature (ZBF) that appears to be a universal aspect of the technique. The technique uses inelastic electron tunneling spectroscopy (IETS) adapted to a new configuration, the "self-assembling tunnel junction" (SATJ), consisting of two metal wires in a cross geometry. In SATJ, a rare-gas barrier film replaces the oxide layer of the metal-oxide-metal junctions normally used in IETS. Preliminary experiments have demonstrated that with this technique it is possible to distinguish between acetylene molecules chemisorbed on the metal electrodes and those that are either physisorbed or incorporated in the rare-gas film. Regardless of the composition of the tunnel barrier film, all data show a region around zero-bias voltage where the junction conductance is significantly reduced, the ZBF. In this project isotope substitution experiments will be performed to measure the ultimate sensitivity of the technique. The goal is to observe and study the spectra of single molecules in order to understand the adsorption and tunneling electron-molecule interaction. The ZBF will be examined as a function of the temperature, barrier film composition, electrode composition, and varying junction conductance with the aim to determine the mechanism behind this poorly understood effect. This research will be performed in an undergraduate institution. Undergraduate students will participate in this project and will learn skills in a research area that will prepare them for graduate school and future employment.%%%In this project a new approach will be used to study the chemical and physical properties of molecules adsorbed on metal surfaces, and to determine a poorly understood effect that is present in these and other experiments, the so-called Zero-Bias Feature (ZBF). With the new experimental approach isotopes of acetylene and of carbon monoxide will be measured to determine the ultimate sensitivity of the technique. The goal is to observe and study individual molecules and thereby obtain a better understanding of the adsorption of molecules on surfaces. The behavior of the ZBF will be studied in detail in order to bring about a better understanding of this phenomenon. This project will be pursued in an undergraduate institution and undergraduate students will participate in the research. They will thereby acquire skills in a field of research that will prepare them for advanced training in graduate school and for future employment.***