Inclusion of dynamic σ-π polarization in π-electronab initio calculations

Summary A method is presented, whereby dynamic - polarization, i.e. the correlation effect expressed by simultaneous (-*, -*) excitations, can be approximately included in a multi-reference configuration interaction (MRCI) or multi-configurational self-consistent field (MC-SCF) calculation, without need to explicitly correlate the sigma orbitals. The method, which we call the capacitance matrix method, is based on the use of conventional one-electron integrals, from which a polarization potential (SPP) contribution is computed and added to the one- and two-electron Hamiltonian. In the present form, the method requires one parameter for each type of atom, and one for each type of bond. These parameters were adjusted to reproduce the dynamic - polarization energy, computed by restricted multi-reference CI calculations, of a number of states of different hydrocarbons, and the agreement was within a few percent. Using the same parameters in CAS (Complete Active Space) SCF calculations of various states of benzene gives excitation energies, when SPP is included, which is comparable to those obtained by much more elaborate MRCI calculations.     

New FIR laser lines and frequency measurements in CD3OD

Twenty-four new submillimeter laser lines in fully deuterated methyl alcohol (CD₃OD) in the wavelength range from 52 to 328 m have been obtained in a Fabry-Perot FIR resonator by optically pumping the methanol with a cw CO₂ laser. We have made accurate wavelength measurements and have determined the relative polarization of most of the known CD₃OD laser lines. The frequencies of 13 of the strongest lines were also measured.Contribution of the U.S. Government, not subject to copyright.     

Polarization of coherent synchrotron radiation from an electron beam rotating in a plasma

After eliminating reflections from the walls of the plasma container, we observed polarization of the coherent synchrotron radiation from a relativistic electron beam rotating in a plasma. Several features of the polarization agree well with calculations based on the single particle synchrotron radiation theory. A particular polarization ratio (Fig. 3) does not, however. We deduce from this direct diffraction of the radiation by the beam electrons. This is strong evidence for beam-particle bunches of size cm. Also, there must be some absorption of the extraordinary wave to account for the observations. We suggest a way to apply these results to measure the pitch angle of the beam.Work supported by Army Research Office.     

偏振模色散前馈方案中偏振主态研究

前馈偏振模色散（PMD）补偿系统中重要的一项是要精确得到链路中的偏振主态（PSP）方向。通过在实验中加入扰偏器，分别用矢量法和粒子群优化（PSO）算法来拟合实验结果得到椭球，从而用椭球法得出了主态方向。结果表明：矢量法在获得椭球要比PSO算法更精确、速度更快以及所得到PSP方向更准确，其更适合用于前馈补偿方案中。     

晶体型二阶偏振模色散模拟器

报道了一种新型的二阶晶体型偏振模色散(PMD)模拟器,其由3片可产生不同的一阶PMD差分群延迟(DGD)的晶体和1个法拉第旋转器组成,法拉第旋转器理论上可在180°内连续变化。该二阶PMD模拟器实验上能近似模拟从50到200 ps2的二阶PMD。给出了二阶PMD随偏置电压变化的曲线。实验表明,该器件输出的重复性好,响应时间小于1 ms,实验值与理论值近似符合。     

光纤和光缆的偏振模色散系数研究

综述了偏振模色散的概念、偏振模色散对光传输系统的影响、系统对单模光纤偏振模色散系数的要求,以及获得小的偏振模色散光纤和光缆的方法.     

1.3μm高增益偏振无关应变量子阱半导体光放大器

采用低压金属有机化学气相外延法 (LP MOVPE)生长并制作了 1 3μm脊型波导结构偏振无关半导体光放大器 (SOA) ,有源区为基于四个压应变量子阱和三个张应变量子阱交替生长的混合应变量子阱 (4C3T)结构 ,压应变阱宽为 6nm ,应变量 1 0 % ,张应变阱宽为 11nm ,应变量 - 0 95 % ;器件制作成 7°斜腔结构以有效抑制腔面反射。半导体光放大器腔面蒸镀Ti3 O5/Al2 O3 减反 (AR)膜以进一步降低腔面剩余反射率至 3× 10 -4以下 ;在 2 0 0mA驱动电流下 ,光放大器放大的自发辐射 (ASE)谱的 3dB带宽大于 5 0nm ,光谱波动小于 0 4dB ,半导体光放大器管芯的小信号增益近 30dB ,在 12 80～ 1340nm波长范围内偏振灵敏度小于 0 6dB ,饱和输出功率大于 10dBm ,噪声指数 (NF)为 7 5dB。     

Improvement of n-type OTFT electrical stability by gold electrode modification

N-type organic thin film transistors (OTFT) containing modified gold electrodes have been fabricated to investigate the influence of the self assembled monolayer on the transistor characteristics. We report on the effect of drain/source modification by thiol derivatives on the performances, electrical parameters uniformity and electrical stability of C₆₀ transistors. In the literature, electrical instability is often attributed to organic semiconductor (OSC), OSC-insulator interface and insulator. We found here that OSC-metal interfaces affect dramatically the operational stability for bottom gate/bottom contact structure. These effects have been attributed to morphological evolution at the interface metal-OSC induced by the self-assembled monolayers.     

Efcient Multipartite Polarization Entanglement Distribution Over Arbitrary Noise Channel

We present an efcient faithful multipartite polarization entanglement distribution protocol over an arbitrary noisy channel.The spatial degree of freedom is used to carry the entanglement during the transmission.We describe the principle by distributing n-qubit Greenberge–Horne–Zeilinger state and n-qubit W state.Our scheme can be used to distribute arbitrary n-qubit entangled states to n distant locations.The remote parties can obtain maximally entangled states deterministically on the polarization of photons.Only passive linear optics are employed in our setup,which makes our scheme more feasible and efcient for practical application in long distance quantum communication.     

Synthesis and Characterization of Hydrophilic Trityl Radical TFO for Biomedical and Biophysical Applications

Tetrathiatriarylmethyl (TAM, trityl) radicals have found wide applications as spin probes/labels for EPR spectroscopy and imaging, and as polarizing agents for dynamic nuclear polarization. The high hydrophilicity of TAM radicals is essential for their biomedical applications. However, the synthesis of hydrophilic TAM radicals (e.g., OX063) is extremely challenging and has only been reported in the patent literature, to date. Herein, an efficient synthesis of a highly water-soluble TAM radical bis(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)-mono-(8-carboxyl-2,2,6,6-tetrakis(2-hydroxyethyl)benzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)methyl (TFO), which contains four additional hydroxylethyl groups, relative to the Finland trityl radical CT-03, is reported. Similar to OX063, TFO exhibits excellent properties, including high water solubility in phosphate buffer, low log P, low pK_a, long relaxation times, and negligible binding with bovine serum albumin. On the other hand, TFO has a sharper EPR line and higher O₂ sensitivity than those of OX063. Therefore, in combination with its facile synthesis, TFO should find wide applications in magnetic resonance related fields and this synthetic approach would shed new light on the synthesis of other hydrophilic TAM radicals.