You Teng-Hui,Yang Wei,Hui Hao-Hao,Lei Xiang-Yang,Wang Tian-Yu,Zhang Qing-Hua,Ju Xin,Deng Xue-Ran
The purpose of this study is to analyze the damage of antireflective (AR) coating over potassium dihydrogen phosphate (KDP) crystal subjected to multi-pulse laser irradiation at low flux under vacuum. Fresh silica AR was characterized as a reference; Atomic Force Microscope (AFM), Scanning Electron Microscopy (SEM), profilometer, and Scanning Near-Field Optical Microscope Photo-induced Force Microscope (SNOM-PiFM) were employed to analyze the characteristics of coatings. The experimental results indicated that the damage of AR coating over the KDP crystal was mainly caused by partial exfoliation, which exposed silica particles beneath the surface. It was found that the accumulated tensile stress led to coating damage with the increase of laser pulse. The initial coating damage was observed to extend and interconnect to form large-area exfoliation. Splitting mechanism of SiO–Si TO 3 was observed at vibration mode peaks of 1064 cm −1 and 1096 cm −1 showing progressing irradiation damage. Based on this study, it would be helpful to suppress the damage probability of AR coating over KDP crystal applied in high-power laser systems. Moreover, the applicability of SNOM-PiFM method to study the Infrared Radiation (IR) spectra of ultra-thin coatings with transparent substrates was proposed.
Dou Zhao,Xin Liu,Jingyi Yu,Meng Xu,Binbin Zhang,Yadong Xu,Wanqi Jie
A photoconductive gain (up to 400%) is observed in a 4-hydroxycyanobenzene (4HCB, C7H5NO) bulk organic semiconducting detector, resulting in a high sensitivity of 38.8 μC Gyair−1 s−1 cm−2 under 50 kVp X-ray beam irradiation. The gain variation tendency as the function of both the applied bias voltage and the incident X-ray dose rate is revealed. A rising stage at the gain versus dose rate curve is observed at the low-flux range of X-ray irradiation, attributed to the trap-filling process. A deep-trapping dependent model is proposed, in which the hole injection assisted by trapped electrons is responsible for the gain.
A microbe-rich cake layer (i.e., a membrane biofilm) may maintain a stable hydraulic resistance at low fluxes because the microorganisms may decompose organic foulants and create cavities in the cake layer. However, these microorganisms cannot decompose the inorganic particles, which can increase cake resistance because of the synergistic fouling effect with organic foulants. To gain a better understanding of the effect of microorganisms on the microbe-rich cake layer containing inorganic particles, we investigated the change in hydraulic resistance, structure, and composition during the transition of cake layers from a microbe-poor state to a microbe-rich state, at the flux of 5, 10, and 30 L·m −2 ·h −1 . And we used SiO 2 particles (2.5 μm in diameter) and sodium alginate to simulate inorganic particles and organic foulants. The results showed that when the cake layer was transformed from a microbe-poor state to a microbe-rich state, the hydraulic resistance was reduced, the structure became looser, and inorganic particles were partially detached. These changes were more pronounced for the cake layer under an ultra-low flux of 5 L·m −2 ·h −1 , with 62% and 47% reductions in the hydraulic resistance and inorganic particles, respectively. These results indicated that the fouling by inorganic particles could be reduced by the microorganisms at ultra-low fluxes. Cake composition analysis , forces balance analysis, and computational fluid dynamics simulation suggested that the reduced fouling could be derived from the reasons 1) the biodegradation of organic foulants could promote the detachment of inorganic particles, and 2) the microbial-induced cavities at ultra-low fluxes could reduce the synergistic fouling effect by inorganic particles and organic foulants.
危险品化学品经营许可证（带存储）