Quantum coherence in A-three-level system driven by bichromatic coupling field

<正>We present a theoretical study of quantum coherent effects in a A-three-level system with a strong bichromatic coupling field and a weak probe field.When one component of the strong bichromatic coupling field is resonant with a corresponding transition and the other is detuning with an integer fraction of the Rabi frequency of the resonant field, the absorption spectrum exhibits a series of symmetrical doublets.While two frequencies of the strong bichromatic coupling field are symmetrically detuned from the transition,the position and the relative intensity of the absorption peak are both affected by the coupling field intensity and detuning.An explanation of the spectrum is given in term of the dressed-state formalism.     

茶叶及其组份的红外光谱研究

采用光学方法针对四种茶叶及其四种主要组份在800～3800 cm-1中红外"指纹"特征区域的光谱进行系统研究,采集了不同产地的碧螺春和铁观音以及决定茶叶品质的主要成份中咖啡因、谷氨酸和表儿茶素和花青素类物质的中红外光谱.通过建立模型对各特征光谱进行主成份拟合分析了茶叶品种、产地差异与各主要成份含量的关系.结果表明,不同茶叶之间的差异可表现在其主成份相对含量上:对于不同种类茶叶的碧螺春和铁观音,差异主要表现在茶叶有效成份的含量不同,前者中的各组份含量相对较低;对于不同产地的同种茶叶,差异主要表现在咖啡因和表儿茶素的相对含量不同,其中原产地茶叶中含量相对较高.此研究为利用光学方法对茶叶的种类和品质实现快速检测提供重要参考.     

双能级系统中的光场驱动吸收特性和粒子布居调控

摘要：原子系统中的相干效应一直是当前科学研究的热点。本文在典型的双能级系统中引入光场激发能级之间粒子的相干跃迁,通过讨论光场开启后直到系统达到稳定的量子相干过程,分析系统从瞬态到达稳态的吸收特性和粒子布居特性,并进一步讨论通过改变光场强度对其特性进行的调控。     

NO（D^2∑）共振增强的多光子离化谱

利用皮秒Nd：YAG激光器泵浦的光学参量发生傲大器作激发源，获得了NO分子在460～570nm波长范围内的多光子离化谱，测量了离化信号随激光强度的关系，其近五次方关系表明在460～570nm波长范围内NO分子吸收5个光子而离化。通过对谱线的归属，确认在此波长范围内，NO分子的离化过程是通过高激发态D^2∑的共振增强的多光子离化过程。用最小二乘法拟合，获得了D^2∑态的基振动频率和相互作用的力常数。     

NO分子A~2Σ←X~2Π跃迁的激光双光子荧光激发谱

以Nd :YAG脉冲激光器泵浦的光学参量发生器 放大器 (OPG OPA)作激发光源 ,获得了 4 2 0～ 4 72nm波长范围内NO分子的双光子激光荧光激发谱 ,并利用此技术对NO分子的能级结构进行了实验研究 ,将所得谱线峰归属为NO(A2 Σ←X2 Π)的跃迁 ,荧光强度随激光强度的二次方变化关系表明此过程是一双光子激发过程。利用实验所得峰值波长计算了NO(A2 Σ)态的基振动频率ωe 和平衡位置的力常数k。通过对NO分子A2 Σ→X2 Π跃迁的荧光时间分辨光谱进行实验研究 ,得到 2 6 6Pa气压下A2 Σ(v′ =0 )态的能级寿命τ=5 3 76ns。测量荧光寿命随气压的变化 ,利用曲线拟合得到NOA2 Σ(v′=0 ,1) 两振动态的自发辐射寿命和无辐射跃迁驰豫速率常数     

日常生活与表面活性剂

本文介绍了表面活性剂在日常生活中的应用,并介绍了它的分类、结构特点、洗涤原理以及今后的发展趋势。     

碘分子高激发态光学双共振多光子离化光谱

本文利用双色双共振多光子离化技术（ＯＯＤＲ－ＭＰＩ）,对Ｉ２分子离子对态Ｆ０＋ｕ态进行了较为仔细的研究,利用已知的分子常数,对所得谱线进行了标识和归属,将Ｔｅ＝５２４００ｃｍ－１,间隔为３７ｃｍ－１的振动序列归属为Ｆ０＋ｕ态的高振动激发态,并确定了多光子激发及离化的跃迁通道     

Variation of electronic transition moment versus internuclear distance for NO (A2∑→ X2∏) transition

Two-photon laser-induced fluorescence spectrum (TP-LIF) of NO is obtained with a Nd:YAG pumpedoptical parametric generator and amplifier as radiation source. Spectral intensity distribution shows thatthe electronic transition moment for NO (A2∑→ X2∏) transition varies significantly with inter-nucleardistance. The variation relationship of the electronic transition moment versus inter-nuclear distance isdeduced with polyminal fit procedure. The spontaneous radiative coefficients for NO (A2∑→ X2∏)transition from v′ = 0, 1 are obtained by combing this transition moment variation with the measurementsof spontaneous radiative lifetime.     

Variation of electronic transition moment versus internuclear distance for NO (A~2∑→X~2Ⅱ) transition

Two-photon laser-induced fluorescence spectrum (TP-LIF) of NO is obtained with a Nd:YAG pumped optical parametric generator and amplifier as radiation source. Spectral intensity distribution shows that the electronic transition moment for NO (A2∑→ X2Ⅱ) transition varies significantly with inter-nuclear distance. The variation relationship of the electronic transition moment versus inter-nuclear distance is deduced with polyminal fit procedure. The spontaneous radiative coefficients for NO(A2∑→ X2Ⅱ) transition from v'= 0,1 are obtained by combing this transition moment variation with the measurements of spontaneous radiative lifetime.     

The asymmetry of the Autler－Townes doublet in a three-level system

The effect of the Bloch－Siegert shift on a strongly driven transition is studied in a three-level double-resonance configuration and the result is presented in this paper. We show that when a resonantly driven transition is probed to a third level, the Bloch－Siegert shift leads to an asymmetric Autler－Townes doublet. An important conclusion is that the asymmetry depends only on the driving field intensity, in contrast to a previous study where it is reported that the asymmetry depends not only on the driving field intensity but also on the characteristics of the three-level system. Our result implies an alternative way of measuring the Bloch－Siegert shift.