合成4-氯-7-甲氧基-6-硝基喹唑啉的工艺改进

以2-氨基-4-氯苯甲酸为原料,经环合、硝化、甲氧基化和氯代反应合成了4-氯-7-甲氧基-6-硝基唑啉,总收率42.8%,其结构经1H NMR和MS确证。     

Study of intensity-dependent nonlinear optical coefficients of GaP optical crystal at 800 nm by femtosecond pump-probe experiment

The intensity-dependent two-photon absorption and nonlinear refraction coefficients of GaP optical crystal at 800 nm were measured with time-resolved femtosecond pump-probe technique. A nonlinear refraction coefficient of 1.7×10-17 m2/W and a two-photon absorption coefficient of 1.5×10-12 m/W of GaP crystal were obtained at a pump intensity of 3.5×1012 W/m2. The nonlinear refraction coefficient saturates at 3.5×1012 W/m2, while the two-photon absorption coefficient keeps linear increase at 6×1012 W/m2. Furthermore, fifth-order nonlinear refraction of the GaP optical crystal was revealed to occur above pump intensity of 3.5×1012 W/m2.     

Fe/Al2O3/Fe隧道结特性分析

用离子束溅射方法制备磁性隧道结(MTJ). 研究MTJ样品的隧道结磁电阻(TMR)效应.用X射线 光电子能谱分析了MTJ的软、硬磁层和非磁层及其界面的化学组成与微结构.研究了MTJ的微 结构对氧化铝势垒高度与有效宽度和TMR效应的影响. 关键词： 磁性隧道结 X射线光电子能谱 隧道结磁电阻     

Ni0.8Co0.2-SiO2颗粒膜中的Hall效应

对用离子束溅射制备的Ni_0.8Co_0.2-SiO₂颗粒膜的Hall效应进行了研究.当Ni_0.8Co_0.2合金的含量为43vol%时,在9.5×10⁵A/m的外磁场下,样品的室温Hall电阻率达6.3μΩ·cm ,高于普通磁性金属两个数量级以上,还研究了不同NiCo组分样品的电阻率与温度的关系（95—300K）,发现x＜x_c(逾渗组分)时,电阻率与-logT成正比,电阻温度系数为负;当x＜x_c时,逐渐呈现金属性;而当x≈x_c时,为过渡态.还用透射电子显微镜和振动样品磁强计等手段对样品的微结构和磁性进行了对比研究,表明金属-绝缘体颗粒膜中在逾渗阈值附近有较大的Hall效应,这与样品的微结构有密切关系. 关键词：     

退火对Co35(SiO2)65颗粒膜巨磁电阻效应的影响

采用多靶离子束溅射镀膜机制备了一系列不同退火温度的Co₃₅(SiO₂)₆₅（体积百分数）颗粒膜样品,发现样品的巨磁电阻效应随着退火温度T_a的升高而单调下降.应用磁力显微镜对样品的磁结构进行了观测,发现随着退火温度的升高,近邻的Co颗粒的磁矩倾向于平行排列,形成磁畴结构,从而导致Co₃₅(SiO₂)₆₅颗粒膜巨磁电阻效应单调下降. 关键词：     

三元有序合金GaxIn1-xP(x=0.52)的时间分辨谱

在室温和低温下,测试了有序Ga0.52In0.48P的时间分辨光致发光谱.对实验结果的分析表明,有序GaInP的发光呈双指数规律衰退.室温下,快过程的时间常数在128～250ps范围,低温77K下则都有所变慢,大约在186～564ps范围内;慢过程的时间常数根据不同样品有很大差异,室温下大约在308～1832ps之间变化,低温77K下,则在纳秒量级,最长的甚至达到28ns以上.对两个过程的时间常数随激发功率密度变化的研究表明,快过程对应于有序区域中载流子的复合,慢过程则对应于有序区域和无序区域的空间分离中 关键词： 时间分辨光致发光谱 III-V族半导体 有序合金     

Co-SiO2颗粒膜的巨磁电阻效应

采用离子束溅射方法在玻璃基片上制备了一系列的Co-SiO2颗粒膜样品,并对样品的巨磁电阻效应进行了研究.在Co35(SiO2)65(体积百分比)颗粒膜样品中,观测到室温下近4%的巨磁电阻效应.研究了不同基片温度对巨磁电阻效应的影响并发现,随着基片温度的升高样品的巨磁电阻效应下降.根据样品的电阻率-温度关系曲线分析,在铁磁金属-非磁绝缘介质颗粒膜中,除了电子自旋相关隧穿效应外,可能还存在其他的导电机制.     

Measurement of the third order nonlinear optical coefficients of GaP and chirp parameter of laser pulse

The spectral resolved femtosecond pump-probe experiment is applied to measure the third order nonlinear refractive index coefficient, two-photon absorption coefficient of GaP crystal, and the chirp parameter of the input laser pulses. The results show that nonlinear refractive index coefficient is 2 × 10 -18 m2/W, two-photon absorption coefficient is 2×10-11 m/W at wavelength of 783.5 nm, and the chirp parameter of laser pulse is 1×1025 s-2. Furthermore, the mechanism of nonlinear refraction due to two-photon absorption in GaP crystal and experimental results are discussed.     

Ni/NiO界面的高场磁化研究

报道在表面包覆ＮｉＯ的Ｎｉ超微颗粒和Ｎｉ／ＮｉＯ多层膜中Ｎｉ／ＮｉＯ界面的磁性实验结果．在Ｔ＜８０Ｋ下Ｎｉ／ＮｉＯ界面存在较大的磁化强度（Ｈ＝４０kＯｅ），并随温度上升而快速下降．对高场磁化（５－６５kＯｅ）实验数据进行拟合，结果表明Ｎｉ／ＮｉＯ界面存在类似磁矩排列不一致的结构． 关键词：     

Measurement of the third order nonlinear optical coefficients of GaP and chirp parameter of laser pulse

The spectral resolved femtosecond pump-probe experiment is applied to measure the third order nonlinear refractive index coefficient, two-photon absorption coefficient of GaP crystal, and the chirp parameter of the input laser pulses. The results show that nonlinear refractive index coefficient is 2× 10-18 m2/W, twophoton absorption coefficient is 2× 10-11 m/W at wavelength of 783.5 nm, and the chirp parameter of laser pulse is l× 1025 s-2. Furthermore, the mechanism of nonlinear refraction due to two-photon absorption in GaP crystal and experimental results are discussed.