Influence of annealing treatment on as-grown Ib-type diamond crystal at a high temperature and high pressure

In this paper,we report on the influence of annealing treatment on as-grown Ib-type diamond crystal under high pressure and high temperature in a china-type cubic anvil high-pressure apparatus.Experiments are carried out at a pressure of 7.0 GPa and temperatures ranging from 1700 C to 1900 C for 1 h.Annealing treatment of the diamond crystal shows that the aggregation rate constant of nitrogen atoms in the as-grown Ib-type diamond crystal strongly depends on diamond morphology and annealing temperature.The aggregation rate constant of nitrogen remarkably increases with the increase of annealing temperature and its value in octahedral diamond is much higher than that in cubic diamond annealed at the same temperature.The colour of octahedral diamond crystal is obviously reduced from yellow to nearly colorless after annealing treatment for 1 h at 1900 C,which is induced by nitrogen aggregation in a diamond lattice.The extent of nitrogen aggregation in an annealed diamond could approach approximately 98% indicated from the infrared absorption spectra.The micro-Raman spectrum reveals that the annealing treatment can improve the crystalline quality of Ib-type diamond characterized by a half width at full maximum at first order Raman peak,and therefore the annealed diamond crystals exhibit nearly the same properties as the natural IaA-type diamond stones of high quality in the Raman measurements.     

Gain-assisted indented plasmonic waveguide for low-threshold nanolaser applications

A subwavelength plasmonic indented waveguide with an active InGaAsP core is proposed.The characteristics of the gap plasmon mode and gain required for lossless propagation are investigated and analyzed by the finite element method.We numerically calculate the normalized mode areas and percentages of energy confined in InGaAsP and metal for plasmonic nanolaser applications.It is shown that the indentation of the sidewalls has an optimal value for which the lasing threshold gain is minimal.The structure could enable low-threshold subwavelength lasing and applications for optoelectronic integrated circuits.     

氢化物发生—原子荧光法测定不同产地绞股蓝及其根际土壤中As,Hg,Se

通过优化了的氢化物发生—原子荧光法测定了7个省产绞股蓝及其根际土壤中As,Hg,Se三种元素的含量,研究结果表明:7个省产绞股蓝中As,Hg,Se的含量存在较大差异,但As和Hg两种重金属元素含量均低于《药用植物及制剂进出口绿色行业标准》中As和Hg的限量标准。Se元素含量同根际土壤中Se元素含量显示极显著相关性,故湖北恩施富硒区产绞股蓝中Se含量明显高于其他6省产绞股蓝。研究结果可以初步判定,绞股蓝中Se元素主要来源于土壤,而As和Hg元素的积累则不同于Se元素,还可能受到大气气溶胶的干、湿沉降等因素的影响。     

Pressure dissociation of dense hydrogen

The self-consistent fluid variational model （SFVM） has been used to describe the pressure dissociation of dense hydrogen at high temperatures. This paper focuses on a mixture of hydrogen atoms and molecules and is devoted to the study of the phenomenon of pressure dissociation at finite temperatures. The equation of state and dissociation degree have been calculated from the free energy functions in the range of temperature 2000-10,000K and density 0.02-1.0g/cm^3, which can be compared with other approaches and experiments. The pressure dissociation is found to occur in higher density range, while temperature dissociation is a more gradual effect.     

大管径油气两相流流型变化机理的研究

本文对大直径水平和不同倾角的倾斜管道内油气混输流动的流型及流行转换进行了研究,探讨大直径油气混输管道不同倾斜度油气两相流动过程中段塞流的形成机理。在大型多相流流动模拟实验装置上,模拟油气在大直径管道内的混输流动。通过改变倾斜角度,研究倾角分别为1°、5°以及10°下的油气两相流流型及流型转换的特性,实验结果表明,倾斜角度对段塞流流型的产生及其变化影响显著。     

A Scheme for Atomic Entangled States and Quantum Gate Operations in Cavity QED

We propose a scheme for controllably entangling the ground states of five-state W-type atoms confined in a cavity and realizing swap gate and phase gate operations. In this scheme the cavity is only virtually excited and the atomic excited states are almost not occupied, so the produced entangled states and quantum logic operations are very robust against the cavity decay and atomic spontaneous emission.     

BBOⅠ类相位匹配光参量放大中群速失配的补偿

描述了在BBOⅠ类相位匹配的飞秒光参量放大（OPA）中，利用非共线结构和倾斜抽运光的脉 冲波面来完全补偿三波群速失配的方法.理论计算了三波群速匹配时，非共线角、相位匹配 角、抽运光的脉冲波面倾斜角随信号光波长的变化，并分析了对抽运光光斑尺寸的要求和对 空间走离长度的影响.结果表明，利用该方法不仅能够实现最大的参量带宽，而且能够完全 补偿飞秒OPA中三波的群速失配.此外，选取合适的抽运光光斑尺寸和非线性晶体的长度对提 高参量增益也至关重要. 关键词： 群速匹配 非共线相位匹配 脉冲波面倾斜 飞秒光参量放大     

两种新型芴类衍生物的三光子吸收特性研究

研究了两种新型芴类衍生物9，9_二（2_乙基已基）_2，7_二咔唑_9H_芴（简记为DCZF）和9 ，9_二（2_乙基已基）_2，7_二（2_（4_甲氧基）苯_2，1_乙烯基）芴（简记为BMOSF）在N ，N_二甲基甲酰胺（DMF）中的线性吸收和单光子荧光行为，并用脉冲宽度为38ps，重复 频率为10 Hz的1064 nm Nd：YAG脉冲激光研究了两种化合物的三光子吸收性质.结果表明： 两种新材料的最大线性吸收峰分别位于330和380nm，吸收区域覆盖了270—420 nm波段. 两种化合物的荧光带位于蓝_紫区，中心波长为369和442 nm，都具有较小的斯托克斯位移. 化合物DCZF和BMOSF的三光子吸收系数分别为γ_DCZF=678×10^{- 20} cm3/W²和γ_BMOSF=592×10^-20 cm³/W². 同时， 两种新材料还表现出明显的三光子吸收光限幅效应，当入射光强分别为8和6GW/cm²时，非线性透过率分别达到30%和45%. 关键词： 芴类衍生物 三光子吸收 光限幅 非线性透过率     

Temperature dependence of radiation-induced attenuation of optical fibers

We investigate the temperature dependence of radiation-induced attenuation (RIA) at 1 310 nm for a Ge/P co-doped fiber after a steady-state γ-ray irradiation.A γ irradiation facility 60Co source is used to irradiate the fiber at a dose rate of 0.5 Gy/min,satisfying a total dose of 100 Gy.The test temperature ranges from-40 to 60℃ by 20℃,and the RIA of the fiber is obtained using a power measuring device.The experimental result demonstrates that RIA exhibits a steady,monotonic,and remarkable temperature dependence after approximately 48h of accelerated annealing at 70℃.The optical fiber irradiated with a high dose and annealed sufficiently can be used as a temperature sensor.