ULTRAHIGH DATA DENSITY STORAGE WITH SCANNING TUNNELING MICROSCOPY

Ultrahigh density data storage devices made by scanning probe techniques based on various recording media and their corresponding recording mechanisms, have attracted much attention recently, since they ensure a high data density in a non-volatile, erasable form in some kinds of ways. It is of particular interest to employ organic polymers with novel functional properties within a single molecule (or a single molecular complex) for fabricating electronic devices on a single molecular scale. Here, it is reported that a new process for ultrahigh density and erasable data storage, namely, molecular bistability on an organic charge transfer complex of 3-nitrobenzal malononitrile and 1,4-phenylenediamine (NBMN-pDA) switched by a scanning tunneling microscope (STM). Data density exceeds 10¹³ bits/cm² with a writing time per bit of ～1μs. Current-voltage (I/V) measurements before and after the voltage pulse from the STM tip, together with optical absorption spectroscopy and macroscopic four-probe I/V measurements demonstrate that the writing mechanism is conductance transition in the organic complex. This mechanism offers an attractive combination of ultrahigh data density coupled with high speed. The ultimate bit density achievable appears to be limited only by the size of the organic complex, which is less than 1nm in our case, corresponding to 10¹⁴ bits/cm². We believe that provided the lifetime can be improved, molecular bistability may represent a practical route for ultrahigh density data storage devices.     

Fabrication of strong long-period gratings in hydrogen-free fibers with 157-nm F2-laser radiation

Long-period gratings were fabricated in standard telecommunication fiber (Corning SMF-28) by use of what is believed to be record short-wavelength light from a 157-nm F(2) laser. Strong loss peaks were formed without the need for enhancement techniques such as hydrogen loading. The magnitude of the attenuation peak was sensitive to the single-pulse laser fluence, decreasing with increasing pulse fluence as a result of nonuniform 157-nm laser interaction with both the fiber cladding and core. The long-period fiber gratings have good wavelength stability (Dlambda~7 nm) under thermal annealing at 150 degrees C.     

磁流变体流变学特性研究

对所研制的矿物油介质和硅油介质磁流变体样品的零场粘度、磁流变性能、示功及速度特性进行了系统的测试和分析,并对其影响因素进行了详细的讨论。研制的磁流变体零场粘度小于0．5Pas(γ=81s^-1)且具有良好的粘温特性;磁流变体的剪切应力接近和超过70kPa(B＝6000Gs);在智能减振器的应用试验中获得理想的示功特性曲线。     

Diode-pumped Q-switched Nd:GdVO4/KTP green laser formed with a flat–flat resonator

A diode-pumped acousto-optically Q-switched intracavity frequency-doubled Nd:GdVO₄/KTP green laser formed with a flat–flat resonator was demonstrated. 3.05 W of average green output power at pulse repetition frequency (PRF) of 40 kHz was obtained with an optical conversion efficiency of 18.4%, the effective intracavity frequency-doubling efficiency was 57%. At the incident pump power of 15 W, the shortest laser pulse occurred at PRF of 25 kHz with FWHM width of 14 ns, yielding the highest peak power of 7.44 kW; while the largest pulse energy of 0.14 mJ was achieved at PRF of 15 kHz.     

用电阻箱自组电桥的桥臂电阻选择

本文分析了用电阻箱作桥臂电阻自组电桥的灵敏度及测量结果不确定度,给出桥臂电阻的选择原则。     

共聚物混溶性热力学-分子内排斥作用与附加共聚焓

基于聚合物分子间物理相互作用和统计平均场理论,引入附加共聚焓定义,使聚合物分子间的作用得到量化,同时推导出二元共混体系相互作用参数和三元共混体系混合焓关系式.利用所导出的公式解释一些常见聚合物共混体系和增溶体系.导出的关系式很好地解释了聚合物的热力学混溶性,但不能解释聚合物共混增溶作用.     

β－环糊精对Pb（Ⅱ）－四（－3溴－4－磺酸基苯基）卟啉显色反应增敏作用的研究

本文研究了β－环糊槽（β－ＣＤ）对Ｐｂ（Ⅱ）－四（－３溴－４－磺酸基苯基）卟啉（ｍ－Ｂｒ－ＴｐｐＳ４）显色体系的增敏作用，提出了高灵敏度测定痕量铅的分光光度新方法。显色体系的表观摩尔吸光系数为２．５×１０５Ｌ·ｍｏｌ－１·ｃｍ－１。铅在０－１０μｇ／２５ｍＬ范围内符合比耳定律。稳定性好，操作简便，快速。本方法适用于人发和白酒等试样中铅的测定。回收率在９４％－１０３％。     

CCD变积累控制技术

在分析微光图像噪声特性的基础上，提出了通过对微光图像信号进行积分，抑制随机噪声的方法，发展了ＣＣＤ可变积累控制技术，研制了ＣＣＤ外围驱动控制和视频制式转换系统，使激光图像信号直接在ＣＣＤ电荷包中进行多帧累加，有效地抑制了随机噪声，提高了低照度与低对比情况下的信噪比和灵敏度，同时避免了后续实时处理电路的高原干扰，图像质量有了明显的改善。     

掺Bi钇铁石榴石薄膜光波导的线性双折射及消除方法

分析了光的线性双折射对磁光波导ＴＥ－ＴＭ模式转换，法拉第旋转，波导光隔离器隔离比及插入损耗的影响。研究了掺Ｂｉ钇铁石榴石薄膜光波导中的形状线性双折射，应力感生线性双折射及生长感生线性双折射的来源，特性和消除方法。     

自锁模掺钛宝石激光器的泵浦研究

对自锁模掺钛宝石激光器的原理作了较详细的描述，指出克尔透镜效应是形成自锁模的主要原因，但是，只有将克尔透镜自聚焦、振荡光参数和泵浦光参数三者结合起来考虑，才能全面了解自锁模的形成过程，本文从速率方程出发，得出了激光介质增益与光束参数的相对变化曲线，并据此来优化自锁模钛宝石激光器的设计，最后，将计算结果与实验作了比较，两者符合得较好。