超高密度信息存储分子存储及其存储机理

在有机功能纳米薄膜上通过扫描隧道显微技术实现了超高密度的信息存储,存储点的大小在13nm左右,存储点间距为15nm,相应的存储密度为1013bitscm2.实验与理论计算的结果表明,其存储机理是薄膜的导电性质的变化.     

偶氮基染料掺杂薄膜的双光子图象存储

研究了偶氮基染料掺杂薄膜ＭＯ－ＰＶＡ和ＥＯ－ＰＶＡ的双光子存储特性。在对薄膜用Ａｒ＾＋激光作预激发下实现了Ｈｅ－Ｎｅ激光的红光存储。获得了实时和短时存储照片。光电记录存储曲线，分析了双光四能级系统的存储机制。实现确定了最佳预激发功率约为０．２８Ｗ／ｃｍ＾２，最小Ｈｅ－Ｎｅ光可存储功率密度低于０．２Ｗ／ｃｍ＾２。     

BR-D96N薄膜共线全息图像存储实验研究

利用一种生物光致变色材料—基因突变菌紫质BR-D96N薄膜的光致变色特性,实现了可擦写式共线全息图像存储实验.对于光密度为3.0的BR-D96N薄膜,在700mW/cm2的记录光强下(波长为632.8nm,物光、参考光光强比为约1∶1.2),全息图建立的最佳曝光时间约为3s,最佳再现光强约为50mW/cm2,全息图寿命约为10min.实验表明:共线全息存储技术光学系统简单,系统体积小,受存储环境的影响低,并能够实现高密度存储;同时也实验验证了BR-D96N薄膜具有响应速度快,感光灵敏度高,擦写次数高,稳定耐用,使用方便等优点,可以作为一种较灵敏的可擦写共线全息记录介质.     

有机复合薄膜中超高密度信息存储研究

利用大气中工作的扫描隧道显微镜，在真空蒸发方法制备的有机复合薄膜上，通过施加电压脉冲法做出了信息点阵，信息点大小为1.3nm.电流-电压特性表明：存储区表现为导体特性，非存储区为绝缘体特性.信息存储实验表明：相邻两个信息记录点的间距可小于2nm,信息存储密度可高达2.5×10¹³bit/cm².对信息存储的机制进行了初步分析. 关键词：     

BR-D96N薄膜共线全息图像存储实验研究

摘要:     利用一种生物光致变色材料—基因突变菌紫质BR-D96N薄膜的光致变色特性,实现了可擦写式共线全息图像存储实验.对于光密度为3.0的BR-D96N薄膜,在700 mW/cm2的记录光强下（波长为632.8 nm,物光、参考光光强比为约1:1.2）,全息图建立的最佳曝光时间约为3s,最佳再现光强约为50 mW/cm2,全息图寿命约为10 min.实验表明：共线全息存储技术光学系统简单,系统体积小,受存储环境的影响低,并能够实现高密度存储|同时也实验验证了BR-D96N薄膜具有响应速度快,感光灵敏度高,擦写次数高,稳定耐用,使用方便等优点,可以作为一种较灵敏的可擦写共线全息记录介质.     

磁存储材料的未来发展

从未来微型计算机对磁存储器应具有超高存储密度的要求出发，讨论了磁存储材料的未来发展．并指出，最有希望的材料是沿用传统模式纵向记录的薄膜磁介质和新型的磁光存储薄膜．对于如何实现此超高密度的磁和磁光存储，文章还讨论了各自需要解决的问题及相关的信息存储和读出技术．     

有机单体3-phenyl-1-ureidonitrile薄膜的超高密度信息存储

采用扫描隧道显微镜(STM)在3-phenyl-1-ureidonitrile(PUN)有机单体薄膜上进行了超高密度信息存储的研究.通过在STM针尖和高定向裂解石墨(HOPG)衬底之间施加一系列的电压脉冲,在薄膜上写入了一个稳定的5×6信息点阵,信息点的大小是0.8nm.电流电压(I-V)曲线表明,施加电压脉冲前后薄膜的导电性质发生了变化.信息点的写入机制可能是强电场作用下引发的PUN分子的局域聚合,从而导致薄膜由高电阻态向低电阻态转变. 关键词： 超高密度信息存储 有机薄膜 扫描隧道显微镜(STM)     

纳米电子学中超高密度信息存储研究的新进展

超高密度信息存储是纳米电子学的重要课题，我们根据电荷转移原理，在有机复合薄膜上用扫描隧道显微镜首次得到直径为１３ｎｍ的信息点阵．信息记录点的形成起源于薄膜的局域电导变化，即此有机薄膜具有电学双稳态特性     

推拉型有机材料的多重存储特性研究

将新合成的推拉型偶氮化合物掺入ＰＭＭＡ中制成薄膜器件,研究了该器件的多重存储特性,实现了三重存储摄影记录及三重存储光电时间状态观测,研究了多重存储的竞争现象,给出多重存储有关现象的机理解释。     

共线存储实验及理论分析

以Ar^ 离子激光器共线输出多波长作为光源，以有机导电材料作样品，采用简并四波混频（DFWM）光路装置，实现了多重多波长共线读出实时和记汐存储，获得了良好的照片记录，观测并解释了存储间的竞争现象。     

离子注入/辐照引起Al2O3单晶的改性研究

600K温度下用110keV的He^＋,Ne^＋,Ar^＋离子注入及320K温度下用230MeV的^208Pb^27＋辐照Al2O3单晶样品,研究了离子注入和辐照对Al2O3单晶样品结构和光学特性的影响。从测得的光致发光谱可以清楚地看到,所有样品在波长为375,413和450nm处出现了强的发光峰。且所有5×10^16ion／cm^2注入样品的发光峰均最强。经过高能Pb辐照后的样品,在390nm处出现了新的发光峰。透射电镜分析发现在注入氖样品100nm入射深度以内形成了高浓度的小空洞（1-2nm）,在Ne沉积区域有少量大空洞形成。傅立叶变换红外光谱分析发现,波数在460-510cm^-1间的振动吸收带经过离子辐照后展宽,随着辐照量的增大,该振动吸收强度显著减弱。1000—1300cm^-1对应Al-O-Al桥氧伸缩振动模式的吸收带,辐照后向高波数方向移动。对离子注入和辐照对Al2O3单晶样品结构损伤机理进行了初步探讨。Single crystal sapphire （Al2O3 ） samples were implanted at 600 K by He, Ne and Ar ions with energy of 110 keV to doses ranging from 5 × 10^16 to 2× 10^17 ion/cm^2 or irradiated at 320 K by ^208Pb^27＋ ion with energy of 1.1 MeV/u to the fluences ranging from 1 × 10^12 to 5 × 10^14 ion/cm^2. The modification of structure and optical properties induced by ion implantation or irradiation were analyzed by using photoluminescence（PL） and Fourier transformation infrared spectrum（FIR） spectra and transmission electron microscopy（ TEM ） measurements. The PL measurements showed that absorption peaks located at 375,413 and 450 nm appeared in all the implanted or irradiated samples, the PL intensities reached up to the maximum for the 5 × 10^16 ion/cm^2 implanted samples. After Pb-ion irradiation, a new peak located at 390 nm formed. TEM analyses showed that small size voids,（ 1--2 nm） with high density were formed in the region from the surface till to about 100 nm in depth and also large size Nebubble formed in the Ne-doped region. From the obtained FTIR spectra, it was found that Pb-ion irradiation induced broadening of the absorption band in 460-510 cm^-1 and position shift of the absorption band in 1 000- 1 300 cm^- 1 towards to high wavenumber. The possible damage mechanism in single crystal sapphire induced by energetic ion implantation or irradiation was briefly discussed.     

结构与尺寸对碳纳米管物理吸附储氢的影响

采用巨正则蒙特卡罗方法,在298K和10MPa下,系统地研究了碳纳米管及其阵列的物理吸附储氢量与单壁管的管径、多壁管的层间距和管层数、单壁管阵列的管间距和排列方式的关系.发现单壁管的管径等于6nm时,管内的储氢密度达到最大;多壁管的层间距由034nm增大至061或088nm时,物理吸附储氢量明显增大;单壁管阵列的管间距等于17nm时,其管外间隙处的储氢密度达到最大,且方阵阵列优于三角阵列;当单壁管阵列的管间距大于06nm时,其管外的储氢密度均大于管内的储氢密度.指出合理地选择单壁管的管径、多壁管的层间距、单壁管阵列的管间距和排列方式,可以有效地提高碳纳米管及其阵列的物理吸附储氢量,并给出了相应的理论解释.     

Island-growth of SiCGe films on SiC

SiCGe ternary alloys have been grown on SiC by hot-wall low-pressure chemical vapour deposition. It has been found that the samples cxhibit an island configuration, and the island growth of SiCGe epilayer depends on the processing parameters such as the growth temperature. When the growth temperature is comparatively low, the epilayer has two types of islands： onc is spherical island; another is cascading triangular island. With the increase of the growth temperature, the islands change from spherical to cascading triangular mode. The size and density of the islands depend on the growth duration and GeH4 flow-rate. A longer growth time and a larger GeH4 flow-rate can increase the size and density of the island in thc initial stage of the epitaxy. In our case, The optimal growth for a high density of uniform islands occurred at a growth temperature of 1100℃ for l-minute growth, with 10 SCCM GeH4, resulting in a narrow size distribution （about 30nm diameter） and high density （about 3.5 ×10^10 dots/cm2）. The growth follows Stranski- Krastanov modc （2D to 3D modc）, both of the islands and the 2D growth layer have face-centred cubic structure, and the critical thickness of the 2D growth layer is only 2.5 nm.[第一段]     

The mechanism research of the Cr^4＋Nd^3＋：YAG laser

The 946nm diode-pump microchip self-Q-switched laser of a chromium and neodymium codoped yttrium aluminum garnet crystal material (Cr^{4+}Nd^{3+}:YAG) is studied, especially about its physical mechanism of operation. The {}^4F_{3/2}→{}^4I_{9/2} transition of Nd^{3+} ion is beneficial to achieving laser oscillation in a quasi-three-level system based on coating the cavity mirrors of the microchip with films that suppress the 1064nm operation and enhance the 946nm laser. The Cr^{4+} ion is a saturable absorber. The initial loss N_{t1} is high, which acts as the threshold for laser oscillation. The stable loss N_{t2} is low because the Cr^{4+} ion is acceleratively bleached by the fast enhancement of the oscillating laser. The high N_{t1}, small N_{t2} and fast progresses permit the oscillating laser of the Cr^{4+}Nd^{3+}:YAG to have a good self-Q-switched property whose full width at half maximum is about 4.2ns. Its highest laser power is about 5.7mW. Its peak power is about 150W. Its good fundamental transverse TEM_{00} mode results from the absorption bleaching established by both the pump and oscillating lasers, which suppress other transverse mode and allow the oscillation only in the fundamental transverse TEM_{00} mode.     

A study of isotopically selective photoionization of ytterbium atoms for laser isotope separation

Atomic-vapor laser isotope separation (AVLIS) is studied experimentally and theoretically for ytterbium vapors. The optimum ionization scheme and the process dynamics are determined. The photoionization scheme uses the transitions $$6^1 S_0 \mathop \to \limits^{555.648nm} 6^3 P_1 \mathop \to \limits^{581.067nm} (7/2,3/2)_2 \mathop \to \limits^{582.79nm} (52353cm^{ - 1} ).$$ For a numerical study of photoionization dynamics, the mathematical model of the AVLIS process is used, which is based on the density matrix formalism and Maxwell's equations. Selective photoionization of the¹⁶⁸Yb isotope is simulated numerically. The yield and selectivity of the process are determined. It is shown that the length of the photoionization region is limited because the laser radiation is absorbed by atoms of¹⁷¹Yb and¹⁷³Yb isotopes. The advantage of the laser method over the method using an electromagnetic separator is demonstrated.     

Green and red up-conversion emissions and thermometric application of Er3+-doped silicate glass

The green and red up-conversion emissions centred at about 534, 549 and 663\,nm of wavelength, corresponding respectively to the ${^{2}}H_{11 / 2} \to {^{4}}I_{15 / 2}$, ${^{4}}S_{3 / 2} \to {^{4}}I_{15 / 2}$ and ${^{4}}F_{9 / 2} \to {^{4}}I_{15 / 2}$ transitions of Er$^{3 + }$ ions, have been observed for the Er$^{3 + }$-doped silicate glass excited by a 978\,nm semiconductor laser beam. Excitation power dependent behaviour of the up-conversion emission intensity indicates that a two-photon absorption up-conversion process is responsible for the green and red up-conversion emissions. The temperature dependence of the green up-conversion emissions is also studied in a temperature range of 296--673\,K, which shows that Er$^{3 + }$-doped silicate glass can be used as a sensor in high-temperature measurement.     

Green and red up-conversion emissions and thermometric application of Er^3＋-doped silicate glass

The green and red up-conversion emissions centred at about 534, 549 and 663 nm of wavelength, corresponding respectively to the ^2H11/2 → ^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 → ^4I15/2 transitions of Er^3＋ ions, have been observed for the Er^3＋-doped silicate glass excited by a 978 nm semiconductor laser beam. Excitation power dependent behaviour of the up-conversion emission intensity indicates that a two-photon absorption up-conversion process is responsible for the green and red up-conversion emissions. The temperature dependence of the green up-conversion emissions is also studied in a temperature range of 296-673 K, which shows that Er^3＋-doped silicate glass can be used as a sensor in high-temperature measurement.     

Up-conversion luminescence research of Er（0.5）：ZBLAN material for volumetric display application when excited by 1520nm laser

The up-conversion luminescence of the ZBLAN fluoride glass Er(0.5):ZBLAN, when excited by a 1520 nm semiconductor laser, is studied in this paper. The absorption and common-fluorescence spectra are also measured in order to understand the up-conversion clearly. It is found that there are seven strong up-conversion luminescence lines (406.97^m, 410.42 nm), (521.97^m, 527.56 nm), (542.38^m, 549.27 nm), (654.27^m, 665.70 nm), 801.57^m nm, 819.46 nm, and 840.00 nm, which can be recognized as the fluorescence transitions of ({}^2G^4F^2H)_{9/2}→{}^4I_{15/2},{}^2H_{11/2}→ {}^4I_{15/2},{}^4S_{3/2}→{}^4I_{15/2},{}^4F_{9/2}→{}^4I_{15/2}, {}^4I_{9/2}→ {}^4I_{15/2}, ({}^2G^4F^2H)_{9/2}→{}^4I_{9/2}, and {}^4S_{3/2}→{}^4I_{13/2} respectively. Meanwhile, the small up-conversion fluorescence lines 379.20 nm, 453.10 nm and 490.60 nm are the transitions of {}^4G_{11/2}→{}^4I_{15/2},{}^4F_{5/2}→{}^4I_{15/2} and {}^4F_{7/2}→ {}^4I_{15/2} respectively. It is interesting that the slopes of log F－logP curves, the double-logarithmic variation of up-conversion luminescence intensity F with laser power P, are different from each other for these observed up-conversion luminescence, this being valuable for the volumetric display. Comprehensive discussions find that the {}^4G_{11/2}→{}^4I_{15/2}, (^2G^4F^2H)_{9/2}→{}^4I_{15/2}, (^2H_{11/2}→{}^4I_{15/2},{}^4S_{3/2}→{}^4I_{15/2},{}^4F_{9/2}→ {}^4I_{15/2}), and {}^4I_{9/2}→{}^4I_{15/2} up-conversion luminescences are five-photon, four-photon, three-photon, and two-photon up-conversion luminescences respectively. It is found also that the absorption from ground-state {}^4I_{15/2} level to {}^4I_{13/2} level is very large, which is beneficial to the sequential energy transfer up-conversion to occur.     

Infrared-to-green upconversion luminescence and mechanism of Ho3+, Nd3+ and Yb3+ ions in oxyfluoride glass ceramics

New oxyfluoride glasses and glass ceramics co-doped with Nd^{3+}, Yb^{3+} and Ho^{3+} were prepared. The upconversion of infrared radiation into green fluorescence has been studied for Nd^{3+}, Yb^{3+} and Ho^{3+} in the transparent oxyfluoride glass ceramics. At room temperature very strong green upconversion luminescence due to the Ho^{3+}: ({}^5F_4, {}^5S_2)→{}^5I_8 transition under 800 nm excitation was observed in the glass ceramics. The intensity of the green upconversion luminescence in a 1mol% YbF_3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho^{3+} upconversion luminescence in the oxyfluoride glass ceramics is discussed. The upconversion mechanism is also investigated.     

In-plane current-induced magnetization reversal of Pd/CoZr/MgO magnetic multilayers

High critical current density ($> 10^{6}$ A/cm$^{2})$ is one of major obstacles to realize practical applications of the current-driven magnetization reversal devices. In this work, we successfully prepared Pd/CoZr(3.5 nm)/MgO thin films with large perpendicular magnetic anisotropy and demonstrated a way of reducing the critical current density with a low out-of-plane magnetic field in the Pd/CoZr/MgO stack. Under the assistance of an out-of-plane magnetic field, the magnetization can be fully reversed with a current density of about 10$^{4}$ A/cm$^{2}$. The magnetization reversal is attributed to the combined effect of the out-of-plane magnetic field and the current-induced spin-orbital torque. It is found that the current-driven magnetization reversal is highly relevant to the temperature owing to the varied spin-orbital torque, and the current-driven magnetization reversal will be more efficient in low-temperature range, while the magnetic field is helpful for the magnetization reversal in high-temperature range.