NO_2分子~2B_2电子激发态荧光辐射寿命的实验研究

采用准分子激光泵浦的染料激光诱导的高分辨荧光技术 ,测定了NO2 分子 A2 B2 电子激发态的荧光辐射寿命及其与激发波长、NO2 分子气体压力之间的关系 ,结果表明荧光衰减曲线是单指数的 ,辐射寿命在 2 0 .4 4～ 72 .53μs之间变化 ,利用光谱涨落统计理论对 A 2 B2 电子态的反常长寿命进行了讨论。     

NO2分子(A)2B2电子激发态荧光辐射寿命的实验研究

采用准分子激光泵浦的染料激光诱导的高分辨荧光技术,测定了NO2分子2B2电子激发态的荧光辐射寿命及其与激发波长、NO2分子气体压力之间的关系,结果表明荧光衰减曲线是单指数的,辐射寿命在20.44～72.53 μs之间变化,利用光谱涨落统计理论对(A)2B2电子态的反常长寿命进行了讨论.     

NO2分子2B2电子激发态荧光辐射寿命的实验研究

采用准分子激光泵浦的染料激光诱导的高分辨荧光技术,测定了NO2分 子2B2电子激发态的荧光辐射寿命及其与激发波长、NO2分子气体压力之 间的关系,结果表明荧光衰减曲线是单指数的,辐射寿命在20.44～72.53 μs之间变化,利 用光谱涨落统计理论对2B2电子态的反常长寿命进行了讨论。     

NO2分子电子激发态荧光辐射寿命的测定

利用激光诱导荧光技术,实验测定了NO2分子513～520 nm范围内AA～U22B2电子激发态6个不同振转能级激光诱导荧光衰减寿命,研究了激发态荧光寿命与气压和激发波长的关系,得到了无碰撞衰减寿命和碰撞猝灭系数,并对其反常长寿命进行了讨论     

NO2分子荧光辐射的时间分辨谱

以Nd∶YAG脉冲激光器抽运的光学参量发生器/放大器作激发光源,采用激光诱导荧光光谱技术对NO2分子激发电子态的荧光辐射寿命进行了实验研究。结果显示,NO2分子的荧光辐射寿命与激发波长、样品气压密切相关。不同波长的激光激发NO2分子,激发电子态荧光辐射的时间分辨谱均以双指数规律衰减,荧光辐射由长、短两种寿命成分组成,短寿命成分产生于NO2分子A2B2和B2B1←X2A1激发跃迁的荧光辐射,而长寿命成分产生于NO2分子由X2A1向A2B2与X2A1耦合能级激发跃迁的荧光辐射。通过分析两种寿命成分随样品气压变化的机理,确定了产生短寿命荧光的受激分子主要通过辐射荧光和快速的内转换过程退激发;而产生长寿命荧光的受激分子除辐射荧光外,则主要通过碰撞无辐射跃迁过程退激发。     

NO2分子在440～495 nm范围内的激光诱导荧光激发谱

以 NdYAG脉冲激光器泵浦的光学参量发生器/放大器作激发光源, 获得了室温、低气压条件下, NO2分子在440～495 nm波长范围内的激光诱导荧光激发谱, 将所得谱线峰归属为NO2由基电子态X2A1态向第二电子激发态B2B1态的跃迁, 利用实验所得峰值波长计算了NO2分子B2B1态的角振动频率ωe. 通过对NO2分子B2B1→X2A1跃迁的荧光时间分辨光谱进行实验研究, 得到15 Pa气压下B2B1(0, 9, 0)振动态的能级寿命τ=49 μs. 测量了荧光寿命随气压的变化关系, 利用曲线拟合得到NO2 B2B1(0, 9, 0)振动态的自发辐射寿命τ0≈55 μs和无辐射跃迁弛豫速率常数. kq=1.2×10-9 cm3 molecule-1s-1.     

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     

NO2分子激光诱导荧光辐射寿命的碰撞猝灭速率的实验研究

实验测定了激发波长在５９１～５９４ｎｍ范围,压力在０．１～１５ｐａ时,ＮＯ２分子激光诱导荧光衰减曲线,作几何修正后应用Ｓｔｅｒｎ－Ｖｏｌｍｅｒ模型,得到了零压辐射寿命τ０（１／ｋ０）和碰撞猝灭速率常数ｋｑ,民文献报道基本一致。对ＮＯ２分子激光态能级的反常长寿命和一定压力下出现的双指数衰减等进行了较详细的讨论。     

NO分子A^2∑←X^2∏跃迁的激光双光子荧光激发谱

以Nd：YAD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420～472nm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N0分子的能级结构进行了实验研究,将所得谱线峰归属为NO(A^2∑←X^2∏)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(A^2∑)态的基振动频率ωe和平衡位置的力常数k。通过对NO分子A^2∑←X^2∏跃迁的荧光时间分辨光谱进行实验研究,得到266Pa气压下A^2∑(v′=0)态的能级寿命r=53．76ns。测量荧光寿命随气压的变化,利用曲线拟合得到NOA。三(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。     

NO分子A2∑←X2Ⅱ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420～472nm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∑←X2Ⅱ)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∑)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∑→X2Ⅱ跃迁的荧光时间分辨光谱进行实验研究,得到266 Pa气压下A2∑(v′=0)态的能级寿命τ=53.76ns.测量荧光寿命随气压的变化,利用曲线拟合得到NOA2∑(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.     

Measurement of cross-section of excitation transfer from 3s2 to 4s1 and 5s1 energy levels of neon

Collision induced non-radiative transitions in neon plasma have been studied using high intra-cavity radiation field of a 633 nm He-Ne laser. The transitions, induced from 3s ₂ energy level to 4s₁ and 5s₁ groups of energy levels, have been detected as changes in intensities of the spectral lines originating from these energy levels. From these intensity measurements, the quantities governing the transitions i.e. (i)S ₃ ^e /S _3RT , the ratio of the probabilities of electronic deexcitation to the total radiative deexcitation of energy level 3 (ii) 〈r ₂₃ ^e v _e〉, rate of excitation transfer per particle and (iii)S ₂₃ ^e , the total probability for excitation transfer from level 2 to level 3 at a certain value of electron density have been calculated.     

转动传能中的量子干涉: 干涉角和相对速度的关系

考虑一级含时波恩近似和长程相互作用势 ,Sun提出了转动传能中的量子干涉模型 .在静态池中COA1Π～e3Σ- 和He碰撞的实验已经成功模拟 .为了从实验中直接获得碰撞速度和干涉角的关系 ,Sha提出了利用分子束和离子速度成像技术的实验 .作为理论研究干涉角和碰撞速度的关系 ,计算了不同速度下的干涉角 ,同时获得了变化的趋势 .对在分子束条件下 (通过控制碰撞速度来控制干涉角 )实验具有指导意义     

Collisional contribution to stimulated scattering in plasmas

The influence of collisions on stimulated Brillouin scattering in magnetized plasmas is discussed. It is shown that new effects occur when the magnitude of the electron quiver velocity exceeds the electron thermal velocity.     

Ar- and air-broadening coefficients in the ν3 band of CS2 at room and low temperatures

Using a diode-laser spectrometer, Ar-broadening coefficients for 16 spectral lines in the fundamental ν₃ band of CS₂ have been measured at five temperatures: 298.0, 273.2, 248.2, 223.2 and 198.2 K. These lines with J values ranging from 2 to 64 are located in the spectral range 1519-1547 cm⁻¹. The broadening coefficients are also calculated from a semiclassical impact model performed by using a simple empirical intermolecular potential. From the theoretical and experimental results obtained at the different temperatures, we have determined the n exponent values governing the temperature dependence of the broadening coefficients. The air-broadening coefficients for four spectral lines in the ν₃ band of CS₂ have also been measured experimentally at the same temperatures. They are compared to the values derived from those obtained previously for the perturbers N₂, O₂ and also Ar.     

Lineshape analysis of the J = 3 ← 2 and J = 5 ← 4 rotational transitions of room temperature CO broadened by N2, O2, CO2 and noble gases

Collisional relaxation has been considered for millimeter lines of carbon monoxide at room temperature. Accurate measurements of carbon dioxide- and rare gases-broadened widths have been performed on the J = 3 ← 2 rotational line of ¹²CO by using a video-type spectrometer. Measurements of nitrogen-, oxygen-, and xenon-broadened widths of the J = 5 ← 4 rotational line of ¹³CO were also carried by using a frequency-modulated spectrometer. A lineshape study performed on all the investigated binary systems provide confirmation that Voigt profile is not a suitable model to analyse experimental lines in the millimeter-waves region. On one hand, using this profile in the low pressure range, i.e. in the Doppler regime, the retrieved collisional linewidths do not follow a linear variation with the perturbing gas pressure. On the other hand, regardless of the pressure, lineshapes exhibit a narrowed profile. An accurate analysis of the pressure dependence of relaxation rates show that the Galatry profile is not appropriate and that experimental lineshapes are actually Speed Dependent Voigt profiles. Accurate broadening parameters were retrieved from this profile and compared to previous reported values and predictions calculated from the Robert-Bonamy formalism. Finally a variation of the ratio of relaxation speed dependence to broadening parameters versus relative masses of the collision partners is presented.     

Cs蒸气中的碰撞能量合并和6P3/2和6P1/2间的激发转移

通过激发转移和碰撞能量合并研究了Cs(62P)精细结构混合.单模半导体激光器激发基态Cs原子至6P3/2态,直接荧光是由6P3/2态发射的,敏化荧光是由精细结构碰撞转移和碰撞能量合并产生的.由相对荧光强度得到了转移截面σ(6P3/2→6P1/2)=(1.5±0.5)×10-15cm2,与其它实验结果进行了比较.     

Excitation dynamics during the multiphoton absorption in SF6+buffer-gas mixtures

A detailed analysis of the total average number of absorbed photons 〈n〉_total during Infrared multiphoton absorption processes in mixtures of SF₆-Ar, N₂ and CH₄ buffer gases is presented. The results for 〈n〉_total are deduced using pulsed photoacoustic technique in collisional regime. Complete analysis is based on the theoretical generalized coupled two-level model (GCT) and its application to different gas mixtures. Evaluation of partial 〈n〉_coll. values is presented too, obtained using the results from time-resolved optoacoustic (TROA) and time-resolved absorption (TRA) methods for V-T relaxation times (τ_V-T) and the saturable absorber (SA) method for R,R-T relaxation times (τ_rot.-rel.), and applying them directly to the GCT model. All methods (TROA and SA) and the GCT model use the same photoacoustic results from our experiment under identical experimental conditions.     

NaK分子激发态的预离解和碰撞激发转移

用Ar+激光器固定频率488.0nm线激发Na-K混合蒸汽,NaK分子激发态通过自发辐射、预离解和与基态原子的碰撞激发转移而去布居,测量在不同K原子密度下原子荧光对分子荧光的强度比,结合NaK(E)态寿命,得到了预离解率和碰撞激发转移率.     

An analytic map for space charge in a nonlinear lattice

We propose a simple analytical model for an intense beam in a lattice with localized nonlinearities. In the thin lens limit a single nonlinearity leads to a Hénon like map. When the space charge is present and the core radius is small with respect to the dynamic aperture, the use of a frozen core distribution like KV is justified. In this case we define an analytic map M by composing the phase advance due to space charge, computed at the first perturbation order, with the kick due to the nonlinear force. The corresponding dynamics is almost indistinguishable from the dynamics of the “exact” map, which requires an accurate symplectic integration, if the tune depression is weak enough. The same accuracy is preserved for parametric modulations of the perveance or the beam core radius. The extension to any other distribution is straightforward.     

钠分子高位2~1Ⅱ_g与C~1Ⅱ_u态之间的碰撞能量转移

通过双光子激发和探测后向受激辐射光谱的方法观察了钠分子高位单态2~1Π_g与C~1Π-x间的碰撞能量转移过程。理论上计算的C~1Π_x态的布居分布和由C~1Π_x→X~1∑_g~+跃迁产生的紫外受激辐射光谱,均与实验结果相符。还同时采用二台不同波长的染料激光器分别激发钠分子和钠原子,研究了不同激发态钠原子对钠分子高位激发态能量转移过程的影响。