Laser-Induced Phase Transitions in Gas-Phase Suspended Molecular Nanoparticles

气相悬浮分子纳米颗粒中激光诱导的相变

• 批准号: 24101151
• 负责人: Professor Dr. Karl-Heinz Gericke
• 金额: --
• 依托单位: Institut für Physikalische und Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/24101151?language=en
• 关键词: Laser; Induced; Phase; Transitions; Gas

Experimental and computer-chemical investigation of melting and vaporisation of gas-phase suspended H20 and D2O nanoparticles is proposed. The heating of the particles being initially in thermal equilibrium will be realized by use of infrared-emitting laser sources. HDO will act as an indicator for presence of the liquid phase in the particles. A new technique for generation of mantle-core particles and layered particles composed of different isotopomers, combined with laser heating and sensitive FTIR detection, will allow to get site-dependent structure information for water nanoparticles for the first time. Special efforts will be directed on the investigation of thickness, structure and temperature dependence of the quasi-liquid-layer (QLL) on the particles. The QLL determines the vapour pressure of the particles; the role of quantum effects will be on focus. Other efforts are addressed to study processes of the particles as molecular self-diffusion. Smaller sizes of water clusters in thermal equilibrium with 2 to 100 molecules per particle are aimed for by use of laser-induced explosive particle vaporisation. A bank of computer codes for simulating structure and dynamics of water clusters will be applied for sizes up to n = 1000 molecules and developed for bigger particles parallel to the experimental program. The codes apply Molecular Dynamics, Path Integral Monte Carlo and other methods. The expected results should have major importance to basic water research, to atmospheric and astro-chemical applications as well as to nanoengineering of molecular nanoparticles.

对气相悬浮H20和D2O纳米颗粒的熔融和汽化进行了实验和计算机化学研究。初始处于热平衡状态的粒子的加热将通过使用红外发射激光来实现。HDO将作为颗粒中是否存在液态的指示剂。一种新的产生不同同位素组成的地核颗粒和层状颗粒的技术，结合激光加热和灵敏的FTIR检测，将首次能够获得水纳米颗粒的位置相关结构信息。将专门研究颗粒上准液体层(QLL)的厚度、结构和温度相关性。QLL决定了粒子的蒸汽压；量子效应的作用将集中在焦点上。其他的努力也致力于研究粒子的分子自扩散过程。利用激光诱导的炸药颗粒汽化，目标是在每个颗粒上有2到100个分子的热平衡的较小尺寸的水团簇。一组用于模拟水团簇结构和动力学的计算机代码将应用于最大尺寸为n=1000的分子，并与实验程序并行开发用于更大颗粒的计算机代码。该程序应用了分子动力学、路径积分蒙特卡罗等方法。预期的结果将对基础水研究、大气和天文化学应用以及分子纳米颗粒的纳米工程具有重大意义。