LiNbO3∶Cr∶Cu晶体吸收特性及非挥发全息存储研究

研究了LiNbO3∶Cr∶Cu晶体的吸收特性,发现LiNbO3∶Cr∶Cu（含0.14 wt.% Cr2O3 和 0.011 wt.% CuO）晶体存在两个明显的吸收峰,中心波长分别位于480 nm和660 nm; 随着Cr的含量逐渐减小,Cu的含量逐渐增大,短波段不存在明显吸收峰,掺Cr的含量越大,中心波长在660 nm处的吸收越大；633 nm红光虽然位于中心波长为660 nm的吸收峰内,但它无助于光折变过程.分别采用390 nm紫外光和488 nm蓝光作为敏化光,514 nm绿光作为记录光的记录方案,实现了非挥发全息记录,掺入适量的Cr( 比如NCr=2.795×1025 m－3,NCr/ NCu=1)有助于全息记录性能的提高.     

用小型全息设备做傅里叶变换全息图存储资料实验

阐述了用小型全息设备做傅里叶变换全息图存储资料实验所采用的光路、详细的操作步骤和实验中的关键问题.     

Colliding stacks: A large deviations analysis

We analyze the performance of a prototypical scheme for shared storage allocation: two initially empty stacks evolving in a contiguous block of memory of size m. We treat the case in which the stacks are more likely to shrink than grow, but with the probabilities of insertion and deletion allowed to depend arbitrarily on stack height as a fraction of m. New results are obtained on the m → ∞ asymptotics of the stack collision time, and of the final stack heights. The results of Wentzell and Freidlin on the large deviations of Markov chains are used, and the relation of their formalism to the Hamiltonian formulation of classical mechanics is emphasized. Certain results on higher-order asymptotics follow from WKB expansions.     

High longitudinal selectivity of shifting multiplexing in volume holograms

High longitudinal selectivity of the shifting multiplexing with spherical reference wave is proposed and demonstrated. A simplified method based on wave optics is used for calculating the selectivity, and the result fits well the experimental measurement. Under the paraxial condition, a simple formula for the longitudinal selectivity is introduced. With use of an object lens with effective NA=0.817, we obtain that an FWHM of selectivity is as small as 1 μm.     

原木随机存贮策略的最优化问题

本主要介绍原木经销商在周期内原木变价销售情况下的最佳期初贮存量的决策方法，在建立期望机会成本的数学模型基础上，探讨原木随机存贮策略的最优化问题。     

苝二酸酐与嘧啶衍生物的氢键组装

用半经验AM1方法对苝二酸酐与嘧啶衍生物的1:1及1:2氢键复合物进行理论研究,表明随着氢键数目增多,弱相互作用能变大,主体上的供电基和客体上的吸电基有利于氢键相互作用,氢键导致电子从主体流向客体.用INDO/SCI方法计算配合物的电子光谱,表明其长波吸收峰与主体相比发生兰移,各配合物的长波吸收峰位置相差不大,与实验一致.讨论吸收峰兰移的原因并对电子跃迁进行理论指认,同时得到了配合物的双质子转移势能曲线,给出了相对于N-H键的过渡态和活化能.     

High-throughput concept for tailoring switchable mirrors

The optical properties, the switching kinetics and the lifetime of hydrogen switchable mirrors based on Mg-Ni alloys are determined with particular regard to the composition of the optically active metal-hydride layer in combination with the thickness of the catalytic capping layer. For this, a high-throughput experiment is introduced. The switching kinetics and the reversibility of switchable mirrors are strongly thickness dependent, though the details hinge on the fine structure of the clustered capping layer. Therefore, the kinetics is correlated with the surface structures of Pd on Mg_yNi_1−y as investigated by scanning tunneling microscopy. The results are explained by the so-called strong metal-support interaction (SMSI) state, characterized by a complete encapsulation of the capping layer clusters by oxidized species originating from the support. The SMSI-effect is less important with increasing Pd-layer thickness, and is suppressed by a good wetting of the Pd-clusters on the optically active film. This explains the critical thickness for the catalyzed hydrogen uptake observed in many switchable mirror systems. Moreover, the degradation of the kinetics during cycling is found to depend on the Pd-layer thickness and on the gas environment. Only films, covered with at least 15 nm Pd, show small degradation caused by the SMSI-effect. The SMSI-effect is partly reversible: after changing the gas environment from hydrogen to oxygen, the oxide on the Pd-clusters can be partly removed.     

甲基红染料掺杂的聚乙烯醇薄膜光存储特性的实验研究

用2倍频小型YAG激光(532nm)作为写入光和擦除光,用He-Ne激光器623.8nm线作为读出光,用CCD作为探测器,研究了不同写入光功率下,甲基红/聚乙烯醇(MR/PVA)薄膜光栅生长的动力学过程和不同擦除光功率下,光栅擦除的动力学过程.结合光栅生长曲线的波动现象,对光存储机制进行了新的探讨.实验发现,两写入光和读出光的功率配比为1:1:1时,可获得最大衍射效率,提出读出光对写入过程具有双重作用的物理模型,对此实验结果给出了合理的解释.     

双－全氟烷基氮氧自由基从取代苯甲醛的攫氢反应──用EPR方法建立取代基自旋离域参数σ的新尝试

Ｒ_ＦＮ（Ｏ　）Ｒ_Ｆ和Ｒ_ＦＮＯ的Ｆ１１３溶液在室温下与一系列的对位取代苯甲醛反应，得到稳定的对位取代苯甲酰基全氟烷基氮氧自由基。由△ａ_Ｎ和△ａ_Ｆ~β的σ单参数相关以及△ａ_Ｎ与σ和σ　双参数相关表明：极性效应是影响氟烷基酰基氮氧自由基中氮原子自旋密度变化的主要因素，而自旋离域效应的影响是很小的。     

Schiff碱水杨醛苯甲酰腙的特性

研究了 Schiff碱水杨醛苯甲酰腙 (简称 SBH)晶体在 DMSO及其 DMSO- H2 O的混合溶剂中的红外光谱 ,通过 SBH氘代前后的 IR对比发现 ,羟基氢质子与混合溶剂 DMSO- H2 O(3∶ 1 ,V/ V)产生较大的相互作用。向溶有 SBH的 75 % DMSO- 2 5 % H2 O的溶液滴加 KOH发现 ,SBH分子上的 C O羰基基团先与 KOH作用 ,其后与 O H 羟基基团作用