掺Fe3+A-TiO2粉末的制备及其可见光催化降解碱性品红

以硫酸钛为原料用水热法制备了掺Fe3+TiO2粉末,用SEM测定了样品的形貌和晶型,研究了以自制的掺Fe3+ A-TiO2对碱性品红溶液的光催化降解作用.结果表明:所制备的TiO2为锐铁矿型TiO2(A-TiO2).可见光照射下,用自制的掺Fe3+A-TiO2降解碱性品红溶液的最佳条件是:2mg·L-1的碱性品红溶液中...     

掺Fe(Ⅲ)的A-TiO_2的水热法制备、表征及其光催化活性分析

一定条件下用水热法制备了的掺Fe(Ⅲ)的TiO2晶体,XRD分析结果表明它是锐钛矿型Fe(Ⅲ)的TiO2(A-TiO2).研究了以自制的掺Fe(Ⅲ)的A-TiO2为光催化剂对罗丹明B溶液的降解性能.结果表明,在5 mg/L的罗丹明B溶液中,加入0.1650 g自制的掺Fe(Ⅲ)的5%的A-TiO2,用硝酸调节溶液PH=5后,可见光照射下,43℃恒温磁力快速搅拌反应6 h,罗丹明B降解率为76.5%;同样条件下经254nm紫外光照6 h,降解率达到95.7%.     

可见光下A-TiO2催化降解邻苯二甲酸二甲酯

研究了在可见光(40W白炽灯)照射下,以自制的锐钛型二氧化钛(即A-TiO2)对邻苯二甲酸二甲酯(DMP)的催化降解效果,分析了TiO2的掺Fe3+量、催化剂用量、邻苯二甲酸二甲酯初始浓度和溶液初始pH值等因素的影响.结果表明:在50mg/L的邻苯二甲酸二甲酯溶液(pH=7)中,加入0.0750g自制的掺Fe3+(摩尔分数)3％的A-TiO2,室温下可见光照反应1h,邻苯二甲酸二甲酯的降解率达到84.02％.     

铁掺杂TiO2可见光催化降解溴酚蓝的动力学

用水热法制备了铁掺杂的TiO2晶体粉末,以SEM和XRD表征了样品的形貌和晶型,研究了在不同反应条件下TiO2晶体粉末对溴酚蓝的光催化降解的动力学过程.结果表明:所制备的TiO2晶体为锐钛矿型;可见光照射下,5 mg· L-1的溴酚蓝溶液,掺10％ Fe3+(摩尔分数)的催化剂用量0.0500 g,室温下恒温反应4h时...     

CdS/TiO2/漂珠复合光催化剂制备及其降解高效氯氰菊酯研究

采用溶胶-凝胶-浸渍法制备了Cds/TiO2/漂珠复合光催化剂,通过SEM,XRD对其结构进行了表征.以高效氯氰菊酯(BEC)杀虫剂的光催化降解为模型反应,研究了CdS/TiO2/漂珠的光催化性能,探讨了影响催化剂活性的因素及采用太阳光作光源处理BEC的可行性.结果表明,CdS/TiO2/漂珠投加量为3 000mg·L-1,初始浓度为45 mg·L-1、初始pH为6.5,通气量为200 mL·min-1时间为60 min,BEC降解率分别为92.1%(125W高压汞灯)和79.3%(5 W紫外灯),采用太阳光照射300 min,BEC降解率可达93.4%.BEC的降解反应遵从L-H动力学模型,测得反应速率常数9.80 mg·(L·min)-1,吸附常数4.36×10-3 L·mg-1.     

金属离子对纳米TiO2悬浊液的光催化性能影响的光谱研究

以钛氧有机物为前驱体,利用微乳液法制备了纳米TiO2微晶。用X射线衍射(XRD)和红外光谱(FTIR)等测试技术对产物进行了表征,并就纳米TiO2悬浊液中加入金属离子后光催化降解甲基橙溶液进行了初步的研究。光谱分析表明,纳米TiO2悬浊液中加入Bi3 离子后对甲基橙溶液的光催化降解有很大的促进作用,Bi3 与TiO2质量比为1∶8及TiO2的浓度为1.6g·L-1时光催化活性最佳。     

RuO2/TiO2复合光催化剂的制备及性能研究

采用溶胶-凝胶-浸渍法制备了RuO2/TiO2复合光催化剂, 以紫外灯为光源, 直接耐晒黑G溶液的光催化降解为模型反应, 研究了RuO2/TiO2的光催化性能. 结果表明 掺杂量ω(RuO2)为0.16%、煅烧温度500 ℃、催化剂投加量为5.00 g·L-1时, RuO2/TiO2复合光催化剂催化活性最高. 直接耐晒黑G降解反应遵从Langmuir-Hinshelwood动力学模型, 测得反应速率常数为4.94×10-3 mmol(L·min)-1和吸附常数14.2 L·mmol-1.     

超声喷雾热解法制备氮掺杂纳米TiO_2薄膜及其光催化特性研究

利用超声喷雾热解法在玻璃衬底上制备了不同沉积温度下的氮掺杂纳米TiO2薄膜,并525℃的退火处理.通过SEM,XRD和UV-Vis透过光谱等表征手段研究了TiO2薄膜表面形貌、结构特性和光催化特性,并探讨了掺杂作用机理.SEM结果表明,在400℃温度下掺N(原子数分数4%)的TiO2薄膜表面比较均匀,致密性好;XRD分析得出,该薄膜是多晶锐钛矿结构;UV-Vis透过光谱分析得出,该薄膜在可见光区的平均透过率为82%,吸收边红移77 nm,计算得知其禁带宽度变小.在紫外光的照射下,氮掺TiO2薄膜对亚甲基蓝溶液具有良好的光催化降解作用,降解率可达46.6%.     

基于Er3+：YAlO3/TiO2的可见光催化降解室内甲醛

为使TiO2能够在可见光下发挥其于紫外激发的高光催化活性降解室内甲醛,采用水热处理法将TiO2与掺杂稀土离子Er3+的上转换发光剂Er3+∶YAlO3结合,制备具有可见光响应的Er3+∶YAlO3/TiO2光催化剂,并对其进行了表征分析。结果表明,TiO2以锐钛矿为主,且Er3+∶YAlO3可有效地将可见光上转换至可激发TiO2的紫外光。在箱式反应器中进行光催化降解气态甲醛,研究了甲醛初始浓度与催化剂用量对甲醛降解效率的影响。结果表明,该光催化反应的假一级反应速率常数( kapp )与甲醛初始浓度成正相关,而随催化剂用量的增加先升高后降低。当甲醛初始浓度为0.058 mg/m3、催化剂用量为0.1224 g/L时,kapp最大为3.65×10-3 min-1。该反应符合Langmuir-Hinshelwood模型,反应速率常数为5×10-8 mg/( L·min)。     

紫外光下锐钛矿型二氧化钛对甲基红的催化降解

研究了在紫外光(λ=365nm)照射下,以自制的掺铁锐钛矿型二氧化钛对甲基红的催化降解效果,分析了甲基红初始浓度、二氧化钛的用量、掺铁量、光照时间和溶液初始pH值等因素的影响.结果表明:在15mg/L的甲基红溶液(pH=5)中,加入0.7 g/L自制二氧化钛(掺铁量1％、摩尔分数),室温下紫外光照反应30min,甲基红的降解率达到99.21％.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.