钾蒸汽中双光子激发产生2^3Пg—a^3Σ^＋u扩散带受激辐射

本文报道了在Ｋ２－Ｋ中通过双光子共振激发原子或双光子激发分子产生２＾３Пｇ－ａ＾３Σ＾＋ｕ扩散带辐射的实验结果，并对激发机制以及扩散带辐射随激发能量和温度的变化进行了讨论。     

锂分子2~3π_g-a~3∑_u~+受激扩散带辐射线型的理论计算

本文利用由RKR方法计算得到的锂分子2~3∏_g态和a~3∑_u~+态(束缚部分)的势能曲线求解振动薛定谔方程,获得了2~3∏_9—a~3∑_u~+跃迁的F-C因子,自发辐射系数,进而计算了该跃迁的荧光强度和受激辐射带强度的光谱分布,其结果与实验测得的由双光子激发锂分子产生的受激扩散带辐射相吻合.     

K_2分子2~3∏_g—1~3∑_u~+漫射谱强度的碰撞诱导增强效应

用4415.6ACW激光线获得了5730A附近的K_2分子2~3∏_g—1~3∑_u~+漫射荧光谱。实验研究了缓冲气体Ar气压强P对漫射谱峰值强度I_(diff)的碰撞诱导增强效应。用稳态碰撞模型描述了C~1∏_u—2~3∏_g间的能量转移过程,推导出了I_(diff)-P函数关系,对实验数据进行了令人满意的拟合。这种拟合表明:适当变更实验装置,利用本文模型可以得到C~1∏_u—2~3∏_g间的能级交叉速率和碰撞诱导转移速率。     

钠分子2~3∏_g←X~1∑_g~＋双光子跃迁的研究

通过比较园偏振和线偏振两种激发方式下，钠分子的等频双光子跃迁谱线的强度变化和２３Ⅱｇ→α３∑＋ｕ辐射谱的数值拟合计算，对２３Ⅱｇ←Ｘ１∑＋ｇ的双光子跃迁进行了标识．     

产生钾分子扩散带辐射的碰撞传能研究

用三能级瞬态速率方程，建立了钾分子１ΛＡｇ和２３∏ｇ态的碰撞能量转移的模型，实验上测量了不同温度的２３∏ｇ→α３∑辐射跃迁的荧光寿命，由此给出了１Λｇ和２３∏ｇ态的碰撞截面，理论与实验结果进行了比较。     

钾双原子分子2^3Пg——x^3∑^＋u跃迁扩散带增益特性研究

报道了用单光子激发产生Ｋ２２＾３Пｇ－ｘ＾３∑＾＋ｕ跃迁扩散带的实验结果，讨论了此扩散带发射增益特性随温度和缓冲气体压力等条件的变化规律，实验测得了１．２％ｃｍ＾－１的增益系数。     

不等频两步激发Li蒸汽产生红外受激辐射特性研究

本文首次报道了利用不等频两步激发Li蒸汽,获得了五条红外受激辐射和串级辐射.并对受激辐射特性进行了研究.     

激波管壁AlO自由基B~2∑~+-X~2∑~+和C~2∏_r-X~2∑~+带系辐射光谱的研究

爆轰驱动过程中产生的高温高压气流对铝质膜片、激波管壁产生烧蚀和冲刷作用,以致激波管壁、端盖上附有氧化铝等杂质,而高温下AlO自由基在气体分子的高速碰撞下被激发并产生强烈的辐射,从而干扰了高温气体辐射光谱的分析.用爆轰驱动加热技术将空气加热到4 000～7 000 K,利用多通道光学分析仪对AlO自由基辐射光谱进行分析,实验发现在460～530 nm波长范围内有多支辐射非常强烈的AlO自由基B~2∑~+-X~2∑~+(T_(00)=20 689 cm~(-1))带系辐射谱带,且每支谱带都由多个带头组成,带头间隔约为2 mn,带头处于高频位置并向低频方向伸延.通过实验与理论计算相结合,重点分析了AlO自由基B~2∑~+-X~2∑~+带系辐射光谱的结构特征.AlO自由基C~2∏_r-X~2∑~+(T_(00)=33 047 cm~(-1))带系辐射光谱处于270～335 nm波长范围内,其辐射强度相对于B~2∑~+-X~2∑~+带系较弱,并且与OH基A~2∑~+-X~2∏(T_(00)=32 682 cm~(-1))带系辐射光谱互相干扰而难以分辨,对该波段高温空气的辐射光谱分析产生不利的影响.     

宽波段多步激发K_2-系统产生的钾原子高位态辐射

本文首次报道以690.0～715.0nm宽波段范围内任何波长的脉冲染料激光激发K_2—K系统,由高位钾分子与钾原子碰撞以及分子-原子的混合激发等过程而产生钾原子404.4,404.7和470.05～590.0nm波段内高位态辐射的实验结果,并对激发机制进行了探讨.     

599.2 nm diffuse band radiation generated by two-photon exciting molecular and atomic potassium

Diffuse band radiation around 599. 2 nm in K_2 was generated by the two photon pumping potassium dimers or by the two-photon resonant pumping atomic potassium with following atoms-molecules collision energy transfer. The pumping wavelengths are in a wide range of 697-745 nm. The relevant mechanisms were discussed.     

599.2 nm diffuse band radiation generated by two-photon exciting molecular and atomic potassium

Diffuse band radiation around 599. 2 nm in K_2 was generated by the two photon pumping potassium dimers or by the two-photon resonant pumping atomic potassium with following atoms-molecules collision energy transfer. The pumping wavelengths are in a wide range of 697-745 nm. The relevant mechanisms were discussed.     

双光子激发NO分子里德伯态H~(''''2)Ⅱ~-的光谱研究

本文采用激光双光子激发的方法对NO分子的里德伯态H~(12)Ⅱ-(v=1,2)进行了研究,得到了该能级的光谱常数;观测到了H~(12)Ⅱ-与非里德伯态B~2Ⅱ之间的相互作用现象,并计算出了相应的转动能级位移;研究了H~(12)Ⅱ-能级的主要荧光跃迁通道。     

双光子激发时间分辨荧光光谱测量技术

建立了一台基于高重复频率扫描相机的双光子激发时间分辨荧光光谱测量系统，能够同时测量样品的荧光光谱和寿命. 该系统的时间分辨率为6.5—200ps，光谱分辨率为1—3nm，能够实现快速数据采集以及可靠和可重复的寿命和光谱测量. 利用标准荧光染料(若丹明6G、香豆素314)及其混合溶液对该系统进行了测试，所得到的荧光光谱分布和寿命值与文献报道一致. 实验结果表明，该系统能有效区分多组分荧光团. 这为鉴别多荧光团或多组分生物组织提供了一种独特的对比方法，可用于多光谱分辨荧光寿命成像和荧光共振能量转移成像等方面. 关键词： 荧光寿命 荧光光谱 双光子激发 高重复频率扫描相机     

Light quenching of tetraphenylbutadiene fluorescence observed during two-photon excitation

We observed the steady-state and time-resolved emission of tetraphenylbutadiene (TPB) whea excited by simultaneous absorption of two photons (514 to 610 nm). The intensity initially increased quadratically with laser power, as expected for a two-photon process. At higher laser powers the intensity increases in TPB were subquadratic. The intensity and anisotropy decay times of TPB were unchanged under the locally intense illumination. Importantly, the time zero anisotropy of TPB was decreased under conditions where the intensity was subquadratic. Furthermore, the subquadratic dependence on incident power was not observed for two-photon excitation of 2,5-diphenyloxazole (PPO), for which the incident wavelength does not overlap with the emission spectrum. These results are consistent with stimulated emission (light quenching) of TPB at high laser intensities. The phenomenon of light quenching may be important for other fluorophores used in biochemical research, particularly for the high local intensities used for two-photon excitation.     

Collisional redistribution of energy in the infrared spectrum of potassium vapor under two-photon excitation

The cascade decay of the 6S(4D) levels of the potassium atom, 6S(4D)-5P-5S(3D)-4P, following two-photon excitation of potassium vapor (4S-4P-6S) is investigated experimentally. The dependences of 11 resonant IR line intensities on potassium and buffer gas densities are presented. It is shown that the presence of buffer gas leads to collisional redistribution of radiation, causing suppression of some lines and production of new ones.     

双光子激发钠分子荧光寿命的测量

本文研究了钠分子高位三重态荧光寿命的测量方法。利用倍频晶体模拟等频双光子激发过程和对荧光衰变曲线求卷积的数值计算方法。有效地消除了测量仪器响应函数的影响,测量了Na_2高位三重态2~3∏_g→a~3∑_u~+的荧光寿命。     

基于双光子激发荧光的单分子探测技术研究

介绍采用双光子激发荧光方法进行单分子探测的原理和自行研制的实验装置,激发光聚焦和荧光收集采用共焦方式。选择香豆素C445水溶液作为研究对象,从样品流速、浓度、激光功率、信噪比和检测限等方面探讨了双光子激发荧光的特性。该谱仪目前己达到探测灵敏区内C445的平均分子数为1.5个的检测限     

Fluorescence of horse liver alcohol dehydrogenase using one- and two-photon excitation

We examined the steady-state and time-resolved emission of liver alcohol dehydrogenase resulting from one-photon and two-photon excitation. Previous studies with one-photon excitation revealed that the two nonidentical tryptophan residues display different emission spectra and decay times. The use of two-photon excitation resulted in similar emission spectra, multiexponential intensity decays, time-resolved emission spectra, and anisotropy decays as was observed for one-photon excitation. These results suggest that both nonidentical tryptophan residues are excited to a similar extent for one- and two-photon excitation. However, the limiting anisotropy (r ₀) with two-photon excitation from 585 to 610 nm is below 0.1 and appears distinct from that observed previously forN-acetyl-l-tryptophanamide.Abbreviations LADH liver alcohol dehydrogenase - -NAD⁺ -nicotinamide adenine dinucleotide - OPE one-photon excitation - OPIF one-photon induced fluorescence - TPE two-photon excitation - TCSPC time-correlated single photon counting - TPIF two-photon induced fluorescence     

原子双光子激发截面的计算

在不可约张量法基础上,利用二次量子化方法计算了原子的双光子激发截面.作为一个实例,计算了Hg原子的双光子激发截面.理论结果与实验结果在数量级上有较好的符合.