三乙烯二胺促进炔酸聚乙二醇酯与苯酚的加成反应研究

以单甲氧基聚乙二醇和2-丁炔酸为起始原料,制得2-丁炔酸聚乙二醇酯（1）;以异丙醇为溶剂,三乙烯二胺（DABCO）为催化剂,1与苯酚经Michael加成反应合成了苯酚的聚乙二醇化产物（2）,其结构经¹H NMR和FT-IR确证。在最优反应条件［n（苯酚）:n（1）: n（DABCO）=20:1:20,异丙醇0.5 mL,于室温反应12 h］下,2产率99%。     

Intensifying process of polarization effect within pixellated CdZnTe detectors for X-ray imaging

The intensifying process of polarization effect at room temperature in a pixellated Cadmium zinc telluride (CdZnTe) monolithic detector is studied. The process is attributed to the increase in build up space charges in the CdZnTe crystal, which causes an expansion of the space charge region under the irradiated area. The simulations of electric potential distributions indicate that the distorted electric potential due to the high X-ray flux is significantly changed and even deteriorated due to increasing space charges within the irradiated volume. An agreement between the space charge distribution and electric potential is discussed.