铂基团簇Pt3X(X=Al，Si，Cu)催化水制氢及其水解副产物氧化CO

本文基于第一性原理研究了利用具有幻数结构特点的Pt₃X(X=Al，Si，Cu)团簇仅通过一步反应就能催化分解水制氢的反应过程. 吸附物H₂O@Pt₃X团簇在波长300∽760 nm的紫外和可见光范围内有强吸收，表明太阳光可以方便地用于Pt₃X的催化水解制氢的反应. 此外，水解后滞留在团簇上的O原子可在反应活化能为0.34∽0.58 eV内与CO氧化反应生成CO₂. 这个通过氧化消除“毒性”CO的结果表明了反应副产物有能作催化剂的循环再利用能力. 本文发现生成的CO₂分子还可以在323 K的温度下脱离Pt₃X小团簇.     

Sensitivity to external optical feedback of circular-side hexagonal resonator microcavity laser

The sensitivity to fault reflection is very important for larger dynamic range in fiber fault detection technique. Using time delay signature (TDS) of chaotic laser formed by optical feedback can solve the sensitivity limitation of photodetector in fiber fault detection. The TDS corresponds to the feedback position and the fault reflection can be detected by the laser diode. The sensitivity to feedback level of circular-side hexagonal resonator (CSHR) microcavity laser is numerically simulated and the feedback level boundaries of each output dynamic state are demonstrated. The peak level of TDS is utilized to analyze the sensitivity. The demonstration is presented in two aspects:the minimum feedback level when the TDS emerges and the variation degree of TDS level on feedback level changing. The results show that the CSHR microcavity laser can respond to the feedback level of 0.07%, corresponding to -63-dB feedback strength. Compared to conventional distributed feedback laser, the sensitivity improves almost 20 dB due to the shorter internal cavity length of CSHR microcavity laser. Moreover, 1% feedback level changing will induce 1.001 variation on TDS level, and this variation degree can be influenced by other critical internal parameters (active region side length, damping rate, and linewidth enhancement factor).