Dynamics of molecular alignment steered by a few-cycle terahertz laser pulse

The field-free alignment of molecule ClCN is investigated by using a terahertz few-cycle pulse (THz FCP) based on the time-dependent density matrix theory. It is shown that a high degree of molecular alignment can be obtained by changing the matching number of the THz FCPs in the adiabatic regime and the non-adiabatic regime. The matching number can affect both the maximum value of the alignment and the time at which it is achieved. It is also found that a higher degree of alignment can be achieved by using the THz FCP at lower intensity and there exists an optimal threshold of molecular alignment with the increase of the field amplitude. Also found is the frequency sensitive region in which the degree of maximum alignment can be enhanced greatly by modulating the center frequencies of different THz FCPs. The investigation demonstrates that comparing with a THz single-cycle pulse, a better result of the field-free alignment can be created by a THz FCP at a constant rotational temperature of molecule.     

应用于神经通路研究的微机电系统探针与低功耗低噪声单集成芯片系统

针对神经内海马区谷氨酸化学递质与神经电生理信号的并行双模检测需要, 设计了8通道电化学递质与电生理双模并行检测传感芯片微系统, 系统组件包括:基于SOI(Silicon-on-insulator)工艺衬底制备的微机电系统MEMS(Micro-electro-mechanical system)神经信息检测探针、低噪声颅内神经电小信号放大器、低功耗中速SAR(Successive approximation register)-ADC(Analog/Digital Converter)模/数转换器、精简低能耗OOK(On-Off-Keying)/FSK(Frequency-Shift-Keying)调制射频发射器.本微型神经信息传感芯片系统具有体积小、抗干扰、化学递质与电生理信号并行检测、灵敏性好、线性度高等特点.对电生理裸探针的4个电生理位点表面沉积铂黑, 电极阻抗优化为35.0 kΩ;通过酶固定技术在谷氨酸检测位点上纳米定向修饰酶复膜结构(Pt-mPD-GluOx)以形成具有特异选择性的生物识别点, 实现神经化学递质谷氨酸的检测;在6～35 μmol/L谷氨酸浓度范围内线性度是0.97, 单位面积灵敏度是0.0069 pA/(μmol/L), 电流响应误差<3.0 pA, 表明此探针可以实现特异选择功能.同时, 基于数模混合180 nm的ASIC(Application specific integrated circuit)芯片制造工艺(SmicRF180 nm 1Poly6M)制造的神经电生理传感后端信息调理单芯片, 其内部关键测试指标:微弱小信号低噪系电压放大器(等效输入噪声电压≤0.7 μV rms, 增益>70 dB, 电源/共模抑制比>100 dB等)、SAR-ADC(有效量化位数是12 bits, 功耗1.2 mW, 最大转换速率1 Msps, 信噪比为60.9 dB)、ASK/FSK调制的射频发射器(功放PA 4～5 dBm, 输出功率满足10 m辐射距离).此微型神经信息感知处理芯片集成检测系统, 可为海马区神经通路的研究提供便携、普适性的无线可穿戴设备.