Investigation of New Sensor Concept Using Non-Adiabatic Energy Transfer and "Chemicurrent" Production from Gas Adsorption and Reaction on Ultrathin Metal Films

利用非绝热能量转移和超薄金属膜上气体吸附和反应产生“化学电流”的新传感器概念研究

• 批准号: 0341973
• 负责人: Eric McFarland
• 金额: --
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-15 至 2007-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0341973&HistoricalAwards=false
• 关键词: Investigation; New; Sensor; Concept; Using

The detailed mechanisms and process dynamics by which the transfer of energy occurs during adsorption and reaction on catalytic surfaces are of fundamental interest. In experiments investigating energy transfer during chemisorption we were able to show experimentally that electronic excitations were a significant component of chemisorption energy transfer associated with atomic hydrogen or atomic deuterium on Ag and Cu ultrathin films (Phys. Rev. Letters 82 (2), 446-449 (1999)). With subsequent NSF support we demonstrated the ubiquitous presence of chemically induced charge transport for a variety of chemical interactions on a variety of different metal surfaces (Science 294 (5551) 2521-2523 (2001)). That energy transfer from chemisorption can proceed by direct electronic excitation is a departure from the conventional dogma which holds that multiple phonon excitation is the primary means through which reaction energy is dissipated. We observe the electronic excitations using ultra-thin metal films (~10 nm) deposited onto semiconductors in a Schottky diode detector structure as a "chemicurrent" resulting from reaction induced excited charge carriers which travel ballistically across the metal film and traverse the Schottky barrier. Though many questions were answered during this initial grant period many others were raised with significant implications for our understanding of surface catalyzed reactions and how we might link chemical processes at surfaces and electronics ("chemielectronics"). In our continuing investigations we will work towards: i) measuring the energy distribution of electrons excited in the metal surface, ii) characterizing the dependence of the electronic excitation probability and energy distribution on the kinetic energy of the adsorbate, iii) investigating the role of electronic excitations in surface mediated energy transfer, iv) investigate new device structures with applications to sensors, and v) developing a comprehensive theoretical model to understand and interpret the electronic excitation probabilities and energy distributions. The intellectual merit of our work is in developing a better understanding of the reaction associated electronic excitation phenomena. Broader impacts include potential applications for new sensors and chemielectronic devices as well as in the general area of heterogeneous catalysis. This project will impact basic surface science by helping to clarify our view of surface energy transfer and the connections between chemical and electronic observables. The immediate application will be in the practical area of sensor technology where we will have introduced a new class of solid-state sensor and photovoltaic device while the long-term significance will be in helping to improve our understanding of a basic process in nature. Most importantly, funds from this project will allow the continued high quality education of outstanding young scientists and engineers.

在催化剂表面吸附和反应过程中发生能量转移的详细机制和过程动力学是人们基本感兴趣的。在研究化学吸附过程中能量传递的实验中，我们能够实验地证明电子激发是与氢原子或氢原子有关的化学吸附能量传递的重要组成部分。修订书82(2)、446-449(1999))。在随后的NSF支持下，我们证明了各种不同金属表面上各种化学相互作用的化学诱导电荷传输普遍存在(Science 294(5551)2521-2523(2001))。化学吸附的能量转移可以通过直接电子激发进行，这与传统的认为多声子激发是反应能量耗散的主要方式的教条背道而驰。在肖特基二极管探测器结构中，我们用沉积在半导体上的超薄金属薄膜(~10 nm)作为“化学电流”来观察电子激发，这种“化学电流”是由反应诱导的激发载流子以弹道方式穿过金属薄膜并穿过肖特基势垒而产生的。虽然在最初的赠款期间回答了许多问题，但也提出了许多其他问题，对我们理解表面催化反应以及我们如何将表面的化学过程与电子(“化学电子学”)联系起来具有重要意义。在我们继续的研究中，我们将致力于：i)测量金属表面激发电子的能量分布，ii)表征电子激发几率和能量分布与吸附体动能的关系，iii)研究电子激发在表面介导的能量转移中的作用，iv)研究新的器件结构及其在传感器中的应用，v)建立一个全面的理论模型来理解和解释电子激发几率和能量分布。我们工作的学术价值在于对反应相关的电子激发现象有了更好的理解。更广泛的影响包括新传感器和化学电子器件的潜在应用，以及在多相催化的一般领域。这个项目将通过帮助澄清我们对表面能量转移的看法以及化学和电子观测之间的联系来影响基础表面科学。目前的应用将是在传感器技术的实际领域，我们将在那里引入一类新的固态传感器和光伏设备，而长期的意义将是帮助我们提高对自然界中一个基本过程的理解。最重要的是，该项目的资金将使优秀青年科学家和工程师继续接受高质量的教育。