采用MBE生长1.6～2.3μm InGaAsSb/AIGaAsSb多量子阱

采用分子束外延生长了不同In组分的InGaAsSb/AlGaAsSb多量子阱材料.X射线衍射发现量子阱材料有多级衍射卫星峰出现,表明量子阱的界面均匀性和质量较好.研究了不同In组分与光致发光波长的关系,光荧光谱测试表明.所制备的不同In组分的InGaAsSb/AlGaAsSb多量子阱材料,在室温下的发光波长可以覆盖1....     

可见分光光度法研究In3+与Zr4+、Ce3+、Rh3+和Ga3+的浮选分离

用可见分光光度法研究了溴化四丁基铵-碘化钾-水体系浮选分离铟的行为,探讨了In3+与-些金属离子分离的条件.结果表明,当溶液中溴化四丁基铵和碘化钾的浓度分别为6.0×10-4mol/L和5.0×10-3mol/L时,In3+与Zp+、Ce3+、Rh3+和Ga3+可定量分离.     

乙醇水溶液析相萃取分离和富集TlCl4-

研究了乙醇-(NH4)2SO4-罗丹明B体系析相萃取和富集Tl(Ⅲ)的行为及与一些金属离子分离的条件。(NH4)2SO4能使乙醇的水溶液分成两相,在分相过程中,TlCl4-与罗丹明B(RhB)生成的[TlCl4-][RhB+]能被乙醇相完全萃取。当溶液中罗丹明B,(NH4)2SO4和乙醇分别为0.28 mg/mL,0.30 g/mL和质量分数30%时,Tl(Ⅲ)的萃取率达到97.9%以上,Co(Ⅱ),Pb(Ⅱ),Fe(Ⅲ),Mg(Ⅱ),Ru(Ⅲ),Ni(Ⅱ),Cr(Ⅲ),Ag(Ⅰ)和Cu(Ⅱ)基本不萃取,实现了Tl(Ⅲ)与上述金属离子的分离。方法已应用于合成水样中Tl(Ⅲ)的分离和测定。     

分光光度法研究水-乙醇体系析相萃取分离和富集PdBr_4~(2-)

用可见分光光度法研究了水-乙醇体系析相萃取分离和富集PdBr42-的行为及与一些金属离子分离的条件.结果表明,(NH4)2SO4能使乙醇的水溶液分成两相,在分相过程中,Pd(Ⅱ)与KBr生成的PdBr42-与质子化乙醇(C2H5OH2+)形成的缔合物[PdBr42-][C2H5OH2+]2能被乙醇相完全萃取.当乙醇、KBr和(NH4)2SO4分别为30%、6.0×10-3 mol/,L、0.3 g/mL,pH 3时,PdBr42-的萃取率达到98.6%以上,Fe(Ⅲ),Al(Ⅲ),Cr(Ⅲ),Ag(Ⅰ),Cu(Ⅱ),Ni(Ⅱ),Zn(Ⅱ),Co(Ⅱ),Mn(Ⅱ),V(Ⅴ),U(Ⅵ),Pb(Ⅱ),Ru(Ⅲ),Rh(Ⅲ)和Hg(Ⅱ)基本不被萃取,实现了Pd(Ⅱ)与上述金属离子的分离.     

簇合物(F2GaN3)n(n=1～4)的理论研究

采用密度泛函理论B3LYP/6-311+G*方法,计算研究了(F2GaN3)n(n=1～4)簇合物的结构和性质.研究表明,簇合物(F2GaN3)n(n=2～4)的优化构型均拥有Ga-Na-Ga连接的环状结构.讨论了几何参数随聚合度的变化关系.三聚体的船式构象较椅式构象的能量低16 kJ·mol-1,具有S4对称性的四聚...     

气相色谱-质谱法同时测定蔗汁中的莠去津与莠灭净残留量

建立了气相色谱-质谱法(GC-MS/SIM)同时测定蔗汁样品中莠去津和莠灭净的方法,并优化了样品前处理和色谱条件.在优化条件下,两种除草剂在0.00-0.60 mg/L范围内线性关系良好,方法的检出限(S/N=3)均为0.001 mg/L.在加标水平为0.050-0.100 mg/L时,两种除草剂的回收率在93%-10...     

用近红外透射光谱技术测定精米蛋白质含量研究

应用近红外透射光谱技术．采用3种不同回归统计分析方法建立业米蛋白质含量(PC)定量回归方程。结果表明,用改进的最小二乘法(MPLS)、偏最小二乘法(PLS)和主成分回归法(PCR)进行饺正时．校正标准误差(SEC)、交叉检验标准误差(SECV)分别为0．1258、0．134O(MPLS)．0．1177、0．1175(PLS)．0．1207、0．1275(PCR)校正相关系数(RSQ)和交叉验证相关系数(1-VR)分别为0．9941、0．9931(MPLS)．0．9950、0．9942(PLS)．0．9947、0．9942(PCR)。由此可见,3种回归统计方法在建立业米蛋白质含量回归方程时差异不明显．都具有较好的预测效果。近红外透射光谱法作为一种快速而准确的定量分析手段,在稻米加工企业品质管理、大米品质分析和大米贸易检测上有广阔的应用前景。     

Neutron Irradiation Effect in Two-Dimensional Electron Gas of AlGaN/GaN Heterostructures

AlGaN/GaN heterostructures have been irradiated by neutrons with different fluences and characterized by means of temperature-dependent Hall measurements and Micro-Raman scattering techniques. It is found that the carrier mobility of two-dimensional electron gas （2DEG） is very sensitive to neutrons. At a low fluence of 6.13 × 10^15 cm^-2, the carrier mobility drops sharply, while the sheet carrier density remains the same as that of an unirradiated sample. Moreover, even for a fluence of up to 3.66 × 10^16 cm^-2, the sheet carrier density shows only a slight drop. We attribute the degradation of the figure-of-merit （product of ns×μ ） of 2DEG to the defects induced by neutron irradiation. Raman measurements show that neutron irradiation does not yield obvious change to the strain state of AlGaN/GaN heterostructures, which proves that degradation of sheet carrier density has no relation to strain relaxation in the present study. The increase of the product of ns × μ of 2DEG during rapid thermal annealing processes at relatively high temperature has been attributed to the activation of GeGa transmuted from Ga and the recovery of displaced defects.     

Hydrogen Sensors Based on AlGaN/AlN/GaN Schottky Diodes

Pt/AlGaN/AlN/GaN Schottky diodes are fabricated and characterized for hydrogen sensing. The Pt Schottky contact and the Ti/Al/Ni/Au ohmic contact are formed by evaporation. Both the forward and reverse currents of the device increase greatly when exposed to hydrogen gas. A shift of 0.3 V at 300 K is obtained at a fixed forward current after switching from N2 to 10%H2＋N2. The sensor responses under different concentrations from 50ppm H2 to 10%H2＋N2 at 373K are investigated. Time dependences of the device forward current at 0.5 V forward bias in N2 and air atmosphere at 300 and 373K are compared. Oxygen in air azcelerates the desorption of the hydrogen and the recovery of the sensor. Finally, the decrease of the Schottky barrier height and sensitivity Of the sensor are calculated.     

第十五届全国波谱学学术会议纪要

由中国物理学会波谱学专业委员会主办、中国科学院宁波材料技术与工程研究所承办的第十五届全国波谱学学术会议于2008年10月28日至31日在浙江宁波举行.参加本届会议的有来自内地及港台地区的240多位代表,以大会报告、分组报告和墙报的形式共发表论文近200篇.