Volume-conserved Twist Excited-state of π-Conjugated Molecules

The excited state characters of HY103 have been studied by means of time-resolved photon emission (time-correlated single photon counting) and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normal fluorescence state, and a weak fluorescence emission around 670 nm. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted (VCT) state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of ?-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of ?-conjugated molecules in restricted environment is complex.     

华尔卫星数字电视接收机LNB的供电电路和保护电路的原理及维修

一台已使用五年的华尔HY2000型卫星数字电视接收机,因故障返修。用户自述收不到信号。连接电源试机时,机上数码管显示正常。首先考虑可能是用户误将接收机恢复默认设置,因而接收不到目前中星六号的节     

4′-(对-胺苯基)-2,2′:6′,2′′-三联吡啶光物理性质

用稳态吸收和荧光光谱技术研究4′-(对-胺苯基)取代的三联吡啶配体(APT)分子在不同极性溶剂中的光谱和光物理性质. 在极性溶剂中APT分子存在着双荧光现象,它分别对应于局域激发态和分子内电荷转移态. APT分子的胺基N原子与醇类溶剂之间的氢键作用使该分子在质子性与非质子性溶剂中具有不同的线性关系. 此外,APT分子的三联吡啶部分与锌离子络合以及三联吡啶N4—N8—N14与甲醇分子形成氢键后,在低能区域出现新的吸收光谱带与荧光光谱带,表明在基态和激发态均形成了新的络合物. 时间分辨单光子计数技术测量的APT分子的荧光衰减过程,证明了APT分子的分子内电荷转移机制符合〝两态〞模型.     

飞秒时间分辨实验中相关函数和时间零点的确定

结合飞秒激光在研究分子激发态弛豫动力学中的应用,介绍了几种飞秒时间分辨实验中确定泵浦激光脉冲与探测激光脉冲的相关函数和时间零点的方法.对于波长在可见波段的泵浦和探测激光脉冲,我们可以利用非线性光学的技术手段,探测泵浦光与探测光的和频光的强度随二者间的时间延迟的变化来确定相关函数和时间零点;对于波长在紫外甚至更短的波段的泵浦和探测激光脉冲,由于单脉冲能量比较低,目前还很难利用技术手段来测定泵浦激光与探测激光的相关函数及时间零点,可以利用某些原子气体(如Xe)或某些具有短寿命态的分子作平行实验进行间接测量.     

GPCR A2AAR腺苷受体蛋白的激动剂结合及其诱导的蛋白活性开关构象变化

运用分子动力学模拟,研究了腺苷酸(激动剂)与A_2AAR腺苷受体蛋白的相互作用和配体结合诱导的蛋白动力学变化.识别了与腺苷酸结合力强于0.5 kcal/mol的关键基团：A63^2.61,I66^2.64, V84^3.32, L85^3.33, T88^3.36, F168^5.29, M177^5.38, L249^6.51     

ETC系统中路侧单元下行链路的频谱特性研究

文章介绍了一种采用ADS软件数据流仿真获得射频电路频谱特性的方法,并采用该方法对ETC系统中路侧单元下行链路的频谱特性进行了分析,详细讨论了影响输出信号带外杂散电平的因素,给出了满足国标频谱模板的射频电路合理设计方法即中频调制法,通过解调信号与原信号对比一致性验证了该方法的正确性。该方法虽然稍微增加了射频电路的硬件成本,但给出的射频电路性能指标优异,可有效降低杂散发射电平及对临近信道的干扰,并且工程易实现。     

Experimental investigation about the effect of non-axisymmetric wake impact on a low speed axial compressor

Non-axisymmetric wake impact experiments were carried out after the best exciting frequency for a low speed axial compressor had been found by axisymmetric wake impact experiments. When the number and circumferential distribution of inlet guide vanes （IGV） are logical, the wakes of non-axisymmetric IGVs can exert beneficial unsteady exciting effect on their downstream rotor flow fields and improve the compressor＇s performance. In the present paper, four non-axisymmetric wake impact plans were found working better than the axisymmetric wake impact plan. Compared with the base plan, the best non-axisymmetric plan increased the compressor＇s peak efficiency, and the total pressure rise by 1.1 and 2%, and enhanced the stall margin by 4.4%. The main reason why non-axisymmetric plans worked better than the axisymmetric plan was explained as the change of the unsteady exciting signal arising from IGV wakes. Besides the high-frequency components, the nonaxisymmetric plan generated a beneficial low-frequency square-wave exciting signal and other secondary frequency components. Compared with the axisymmetric plan, multifrequency exciting wakes arising from the non-axisymmetric plans are easier to get coupling relation with complex vortices such as clearance vortices, passage vortices and shedding vortices.     

飞秒荧光亏蚀光谱技术研究液相体系取向弛豫

溶液中分子的快速弛豫过程直接反映了溶液中溶质和周围溶剂分子间的相互作用[1- 3 ] .在液相体系中分子取向通常是随机分布的 .当溶质分子被线偏振光激发至激发态时 ,其分子取向将由原来各向同性的球形分布瞬间变成各向异性的椭球分布 .由于溶质分子周围大量溶剂分子的存在 ,通过二者之间相互作用 ,激发态溶质分子在一定方向上的取向优势将很快弛豫掉 .这种溶液中的取向弛豫过程通常是几个到几百皮秒[1- 3 ] .飞秒分辨荧光亏蚀光谱原理和实验方法见文献[4 - 7] .当溶液中的溶质分子被线偏振飞秒激光脉冲激发至电子激发态时 ,经过一定的延迟…     

用动力学Lie代数方法研究H2在 Ni(100)面离解吸附量子动力学

用动力学Lie代数方法处理H     

一种P波段小型化表贴型T/R组件研制

文章介绍了小型化、表贴型雷达T/R组件的设计方法和实现形式,详细阐述了其工作原理及核心电路设计过程,给出了一体化封装方式的实现途径,并通过T/R组件实物的研制验证了其性能指标。研制结果表明该组件尺寸仅为40mm×25mm×4.8mm,重量不到10g,具有小型、轻质、器件化的特质,已经在某雷达中得到了应用。