基于极紫外自由电子激光的合成氨反应机理研究

Ammonia synthesis is very important for grain production and clean energy, and accurate measurement of key reaction intermediates is of guiding significance for the development of efficient new catalysts. The number density of these key reaction intermediates is very low and can not be stable for a long time. The studies on the structures and dynamics of these species require a high sensitivity and transient detection. The ionization energies of key species such as N, NH and NH2 are 85.3、94.6、103.3 nm, and the effective detection of such species is vacuum ultraviolet (VUV) light source with high performance (tunable wide wavelength, high peak power, short pulse width, etc.). The wavelength range of Dalian ultraviolet free electron laser (VUU-FEL) is 50-150 nm. The peak power is at least five orders higher than that of four-wave mixing method and the ultra-fast time structure with picosecond and femtosecond pulse width. It is very suitable for single-photon soft ionization, high sensitivity and high time resolution detection of molecules and clusters. We use the VUU-FEL light source to obtain the reaction intermediate species of the ammonia synthesis process in situ/online detection. Combined with photoelectron spectroscopy and infrared dissociation spectroscopy, the deep mechanism of chemical reaction is revealed and the important scientific basis is provided for the development of new high efficiency and low temperature ammonia synthesis catalyst.

合成氨对粮食生产和洁净能源至关重要，精确测量关键反应中间体对开发高效新型催化剂具有指导意义。反应过程中的关键中间物种数量密度很低，不能长时间稳定存在，对这些中间物种结构和动力学研究需要高灵敏、瞬态探测实验方法。由于N、NH、NH2等关键物种的电离能分别为85.3、94.6、103.3 nm，有效探测此类物质的先决条件是具有高性能（宽波段可调、峰值功率高、短脉冲等）的紫外激光光源。大连极紫外自由电子激光的波长范围是50-150 nm，其峰值功率比四波混频产生的紫外激光至少高五个数量级，并且具有皮秒和飞秒脉宽的超快时间结构，可以实现单光子软电离，非常适合于分子和团簇的高灵敏度和高时间分辨的探测。本项目拟利用大连极紫外自由电子激光的优越特性，对合成氨的关键反应中间体实现原位/在线探测，与光电子能谱和红外光解离光谱相结合，揭示化学反应的深层次机制，为开发新型低温高效合成氨催化剂提供重要的科学依据。

合成氨对粮食生产和洁净能源至关重要，精确测量关键反应中间体对开发高效新型催化剂具有指导意义。反应过程中的关键中间物种数量密度很低，不能长时间稳定存在，对这些中间物种结构和动力学研究需要高灵敏、瞬态探测实验方法。由于N、NH、NH2等关键物种的电离能大于12 eV，有效探测此类物质的先决条件是具有高性能（宽波段可调、峰值功率高、短脉冲等）的紫外激光光源。大连极紫外自由电子激光的波长范围是50-150 nm，其峰值功率比四波混频产生的紫外激光至少高五个数量级，并且具有皮秒和飞秒脉宽的超快时间结构，可以实现单光子软电离，非常适合于分子和团簇的高灵敏度和高时间分辨的探测。本项目我们利用大连极紫外自由电子激光的优越特性，对合成氨的关键反应中间体实现原位/在线探测，与光电子能谱和红外光解离光谱相结合，揭示化学反应的深层次机制，为开发新型低温高效合成氨催化剂提供重要的科学依据。