Research

发展基于极紫外自由电子激光的中性团簇红外光谱和气溶胶质谱、基于红外自由电子激光的离子团簇红外光谱、光电子能谱等实验方法，研究大气雾霾形成机理和纳米团簇构效关系。

Our research interest is mainly focused on the development of infrared spectroscopy of neutral clusters and aerosol mass spectrometry based on a vacuum ultraviolet free electron laser (VUV-FEL), infrared photodissociation spectroscopy of ionic clusters based on an infrared free electron laser (IR-FEL), and photoelectron spectroscopy based on table-top laser, and their applications to the studies on the formation mechanism of atmospheric aerosols and the structure-reactivity relationship of clusters.

(1) Experimental methods:

      红外-真空紫外光谱

  Infrared-vacuum ultraviolet (IR-VUV) spectroscopy

        红外光解离光谱

  Infrared photodissociation (IRPD) spectroscopy

        光电子能谱

  Photoelectron spectroscopy (PES)

        气溶胶质谱

  Aerosol mass spectrometry

      Light Sources:

       极紫外自由电子激光

       Vacuum ultraviolet free electron laser (VUV-FEL)   

    

        红外自由电子激光

        Infrared free electron laser (IR-FEL)

(2) Theoretical methods:

      量子化学计算

  Quantum chemical calculation   

      分子动力学模拟

  Molecular dynamics simulation

(1) Atmospheric Chemistry

 大气环境污染已经给人类的健康和交通安全等方面造成了严重的危害，治理和调控雾霾迫在眉睫。而从根本上理解大气雾霾的形成和生长机理对于治理大气污染的防治非常重要。大气中的化学物质与水分子作用后，形成分子团簇，这些团簇在生长过程中吸附各种污染分子以及水分子，生长为较大的气溶胶颗粒，并逐渐成长为雾霾。由于在大气条件下从分子形成分子团簇是气溶胶形成机理的关键步骤，所以，分子团簇化学成份与结构的测定对理解凝聚成核过程机理和控制大气颗粒物污染具有指导意义。利用大连极紫外自由电子激光，发展中性团簇红外光谱和气溶胶质谱实验方法，解析中性大气团簇的化学成份和结构，揭示气溶胶的成核动力学机制。

Environmental pollution in the earth atmosphere is becoming a serious issue in the developing world as it is causing severe health and traffic problems for human society. Understanding the mechanism of aerosol growth is the prerequisite to control the atmospheric pollution problems. Generally, molecular clusters are formed initially between pollutant molecules and water molecules, and the clusters then grow in the atmosphere environment to form larger aerosol particles. A key issue in the study of aerosol science is how aerosol particles are formed initially in the atmosphere and how they grow under different conditions. The newly-built Dalian Coherent Light Source (DCLS) facility delivers vacuum ultraviolet free electron laser (VUV-FEL) with a continuously tunable wavelength region between 50 and 150 nm and high pulse energy, and makes it possible to detect neutral complexes with a broad range of ionization potentials. In this lab, the near-threshold ionization mass spectrometry based on the unique VUV-FEL is utilized to study the structure of aerosol particles and unravel the mechanism of aerosol nucleation processes.

(2) Structure-reactivity Relationship of Clusters

催化剂表面活性中心的组成及其与关键反应中间体之间键合结构的表征是诠释催化作用机制的关键。然而，这些物种的数量密度很低，并且不能长时间稳定存在，因此对这些反应中间体的结构和动力学性质研究需要高灵敏瞬态探测实验方法。我们首先采用高分辨反射式飞行时间质谱仪捕捉反应中间体，再利用高灵敏度的红外光解离光谱和光电子能谱等先进光谱方法，表征这些关键物种的几何结构和电子结构，揭示反应机制。

      A number of key reaction intermediates are often involved in the catalytic reaction processes. Due to the low number density and short lifetime of these species, the methods with high sensitivity and transient detection are thus required to explore the structural and dynamic properties of the reaction intermediates. We use high-resolution reflectron time of flight mass spectrometer to capture reaction intermediates, and the high-sensitive infrared photodissociation spectroscopy and photoelectron spectroscopy to characterize the geometric and electronic structures of these key species to understand the elementary and catalytic reaction mechanism.