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1.
利用高分辨的交叉分子束装置研究了F+H2(v=0,j=0, 1)反应在碰撞能1.27 kcal/mol下的动力学行为, 获得了产物HF(v′=1,2,3)转动态分辨的微分散射截面.当反应物H2 处于不同转动量子态j=0和1时,产物HF(v′=2)的散射角分布都主要表现为后向散射,但HF(v′=2)的转动态布居与反应物的转动量子态密切相关,转动激发的H2分子将产生转动“更热”的HF(v′=2) 产物.另外,对于HF(v′=3)产物通道,由于slow-down机理的影响,当H2布居于j=0时前向散射表现更显著.  相似文献   

2.
利用光学-光学双共振光谱技术研究了NaK分子21∑ →61∑ 跃迁线的碰撞增宽.一台单模半导体激光器实现11∑ (v",J")→21∑ (v',J')的跃迁,另一单模半导体激光器激发21∑ (v',J')能级到61∑ 的振转能级,二激光束反向平行通过样品池.谱线总线宽与K原子密度成线性关系,由其斜率得到增宽速率系数kbr=(1.4±0.7)×10-8cm3·s-1.同时研究了21∑ (v=8,J=12)→21∑ (v=8,J=13,14)转动能级间的碰撞激发转移,测量谱线的相对强度,由速率方程得到碰撞转移速率分别为6.1×106和5.2×106S-1.  相似文献   

3.
牛英煜  王荣  修俊玲 《物理学报》2012,61(9):93302-093302
利用两束频率比为1:3的重合脉冲控制分子振转态布居转移. 计算结果表明, 初始态|0,0>到目标态|3,1>的跃迁概率接近100%. 两束脉冲的相位可以控制跃迁概率. 当φ 1 =1.68 π 时, 两束脉冲相互增强, 跃迁概率增加. 当φ 1 =0.64π 时, 两束脉冲相互抵消, 跃迁概率降低. 第二束脉冲的场强对布居转移过程具有较大影响.  相似文献   

4.
利用积分时间分辨荧光光谱方法,研究了RbH(X1∑+,v=0~2)与H2间的振动碰撞能量转移.在Rb-H2混合样品池中,泵浦激光双光子激发Rb原子至6D态,Rb(6D)与H2反应生成RbH(x1∑+)分子,探测激光延迟泵浦激光20 ns,通过激光感应荧光光谱(LIF)的测量,确定了X1∑+(v=0~2,J)原生态的转动...  相似文献   

5.
在Cs-H2混合系统中用激光将Cs原子激发到6P3/2能级,研究了CsH分子的形成机制.利用光学吸收法得到6P3/2态的密度及其空间分布,能量合并过程6P3/2+6P3/2→6D+6S1/2产生6D态原子;猝灭过程Cs(6P3/2)+H2(v=0)→Cs(6S1/2)+H2(v=2)产生H2(v=2)态.由6P3/2态原子密度及6D→6P3/2与6P3/2→6S1/2的荧光比得到碰撞能量合并速率系数,在不同的H2密度下,测量了转移荧光强度I895,得到了H2(2,J)态的产生速率系数kH2(2,J)=1.  相似文献   

6.
采用一束激光为泵浦光另一束激光为探测光的方法,获得CdH分子A~2Π态和X~2∑~+态之间跃迁产生的具有转动结构的多个荧光谱和激发谱带.对荧光的时间分辨研究,给出A~2Π态寿命τ_0=59.5±2.3ns,对A~2Π(v=0)态Cd原子的碰撞猝灭截面为(1.31±0.03)×10~(-15)cm~2;X~2∑~+态寿命τ_0=61.0±4.6μs,引起X~2∑~+(v=0)态寿命衰减的碰撞截面为(1.1±0.1)×10~(-18)cm~2.  相似文献   

7.
本文采用含时波包方法和七维约化量子模型研究了典型碳氢氧化反应O(3P)+CHD3→OH+CD3中反应分子CHD3的转动模式特异性. 发现理论计算反应几率依赖于CHD3转动量子数J在分子对称轴上的投影$K$和在O-CHD3分子间轴上的投影Ktot,即PKtot=K=0>PKtot=K=J>PKtot=J,K=0=PKtot=0,K=J. 这种关系可以用反应物分子相对取向进行解释. 另外,反应物CHD3的转动激发(J≤4)表现出比较弱的促进作用,但是K=0转动态激发的促进作用比K=J的强,主要得益于K=Ktot=0分量的贡献. 该分量对应于CHD3的滚动转动,这种运动形式可以增大初始有效反应碰撞角度的范围.  相似文献   

8.
光外差磁旋转浓度调制激光光谱技术属于一种高灵敏度的吸收光谱测量方法 ,可以用于瞬态分子和激发态分子光谱的检测。采用这种技术分别在 16 4 0 0~ 16 6 5 0cm-1和 174 5 0~ 1775 0cm-1波段内直接观测到CO三重带系d3 Δ←a3 Π(4,0 ) (5 ,0 )振转吸收光谱。这种跃迁的上态d3 Δ1(v =4 ) ,d3 Δ2 (v =4 ) ,d3 Δ1(v =5 )分别与A1Π(v =0 ) ,D1Δ(v =0 )和A1Π(v =1)态存在微扰相互作用。通过对所测量到的 CO三重带系 (4,0 ) (5 ,0 )振转谱带作了包含微扰相互作用在内的分析 ,获得了上态d3 Δ(v =4 ,5 )的精确的分子转动光谱常数。  相似文献   

9.
本文使用交叉分子束方法研究了氟原子和振动激发态氘分子D2(v=1, j=0)的反应. 使用受激拉曼抽运的方法制备了振动激发的D2分子. 实验中未观测到来自于旋轨耦合激发态氟原子F*(2P1/2)与振动激发态D2分子的贡献. 观测到来自于旋轨耦合基态氟原子F(2P3/2)和振动激发态D2的反应信号,相应的产物DF分子布居于v''=2,3,4,5振动态上. 与振动基态反应F+D2(v=1,j=0)相比,振动激发态反应F+D2(v=1,j=0)生成的DF产物转动分布更“热”. 获得了振动激发反应的四个碰撞能在0.32至2.62 kcal/mol范围内的微分反应截面. 在最低的碰撞能0.32 kcal/mol下,所有振动态的DF产物都以后向散射为主. 随着碰撞能的增加,DF产物的角分布逐渐从后向转移到侧向. 测量了DF(v''=5)产物的前向微分散射截面随碰撞能变化的曲线. 前向散射的DF(v''=5)信号出现于1.0 kcal/mol. 在2.62 kcal/mol碰撞能下DF(v''=5)主要为前向散射.  相似文献   

10.
用一束波长为 2 10 .2 7nm的激光将CS2 分子激发至预离解态1B2 (1Σ+ u) ,用另一束激光通过激光诱导荧光 (LIF)方法检测碎片CS ,在 2 5 0 .5~ 2 86 .5nm获得了CS碎片A1Π←X1Σ+ 振转分辨的激发谱 .通过对光谱强度的分析 ,获得了CS碎片v″ =0~ 8的振动布居和v″=1,4~ 8振动态的转动布居 .结果发现 ,碎片CS的振动布居呈双模结构 ,分别对应于CS2 分子1B2 (1Σ+ u)态的两个解离通道 ,即CS(X1Σ+ ,v″=0~ 9) +S(3 PJ)和CS(X1Σ+ ,v″ =0~ 1)+S(1B2 ) .由此得到两个解离通道的分支比S(3 PJ) :S(1B2 )为 5 .6± 1.2 .与前人 193nm处的研究结果相比 ,2 10 .2 7nm激发更有利于S(3 PJ)通道的生成 .此外 ,实验还发现CS的转动布居不满足热平衡分布 ,为两个Boltzmann分布的合成  相似文献   

11.
We report the preparation of D2 molecules in v=2 level in molecular beam condition. A single longitudinal mode laser system was used for excitation of D2 from (v=0, j=0) to (v=2, j=0) with the scheme of stimulated Raman pumping. An excitation efficiency of 25.2% has been achieved, which was determined by the scheme of resonance-enhanced multiphoton ionization. Dependence of relative excitation efficiency on laser energy has been measured. We found that the increasing rate of excitation efficiency became slower as pulse energy of Stokes laser increase, while the excitation efficiency still increases approximately linearly with pump pulse energies up to 60 mJ. The spectral line shapes of Raman transition was also measured at different laser energies and considerable dynamical Stark effect was observed. A single peak was found on the three dimension surface of relative excitation efficiency, indicating the process occurred in the present study is a process of stimulated Raman pumping instead of stimulated adiabatic Raman passage.  相似文献   

12.
The scattering of slow positrons from and NO molecules is treated using exact static interactions and a model potential for correlation-polarisation forces. The quantum coupled equations for the elastic scattering are extended to vibrationally inelastic processes and the different excitation probabilities are evaluated. Comparison with existing experiments for the NO target indicates that the present calculations provide a realistic treatment of positron scattering below Ps formation and give computational estimates on the efficiency of such projectiles in producing vibrationally excited molecules in the ambient gas. Received: 23 April 1999 / Received in final form: 3 June 1999  相似文献   

13.
The influence of vibrational excitation of molecules on negative-ion formation in bulk and in surface is analyzed. The magnetron method is used to study the influence of laser emission on the formation of negative ions of the molecules SF 6 and 12. The SF 6 molecules were excited by absorption of C02-1aser emission in the v 3 band. The 12 molecules were excited by Stokes scattering of the second harmonic of a neodymium laser. It is shown that the cross section for dissociative capture in the presence of vibrationally excited 12 molecules is increased by 3-4 orders. With SF~ molecules vibrationally excited in the beam, studies were made of the effects of formation of negative ions from a hot polycrystallinetungsten filament. The physics of the influence of vibrational excitation on negative-ion formation on a surface is analyzed. The maximum sensitivities of methods of vibrationally excited molecules are estimated.Translated from Lazernye Sistemy, pp. 121–142 1982.  相似文献   

14.
The multiple photon excitation and dissociation of SF6 and hydrogen mixtures is measured by using simultaneously pulsed optoacoustic detection to monitor the energy deposition and time resolved HF fluorescence to monitor the production of vibrationally hot HF. From these studies we deduce that at least three mechanisms lead to production of vibrationally excited HF. One mechanism produces free F from the unimolecular laser-induced decomposition of SF6. The second mechanism involves the reaction between two vibrationally hot SF6 molecules to produce free F. In both of these cases the F atom subsequently react with H2 to produce vibrationally hot HF. The third involves the reaction between a vibrationally hot SF6 molecule and a hydrogen molecule producing vibrationally hot HF directly.  相似文献   

15.
The heat produced in conjunction with the processes of stimulated Raman scattering and four-wave Raman mixing in hydrogen was measured by photothermal refraction spectroscopy. Many vibrational, rotational, and vibrationally shifted rotational Raman lines are exclusively/simultaneously generated by changing the polarization of the laser beam and the hydrogen pressure. Thermal loss occurs predominantly from vibrational Raman scattering, which can be ascribed to a large Raman shift frequency of 4155 cm-1 for the vibrational transition. In contrast to stimulated Raman scattering, little or no thermal loss is observable during the process of four-wave Raman mixing. Received: 12 April 1999 / Revised version: 12 July 1999 / Published online: 20 October 1999  相似文献   

16.
Abstract

Intensities and decay rates of delayed fluorescence initiated by CO2 laser excitation of the triplet-state molecules are used to probe collisional relaxation of vibrationally excited polyatomic molecules. Collisional efficiencies for large polyatomic molecules are found not to exceed the value of 10?2-10?3 even in most favourable case of vibrational energy exchange in collisions between parent molecules. At intermediate levels of excitation (1500—12000 cm?1) the average energies <ΔE> transferred per collision with polyatomic molecules increase as vib>rn, where m≥2, and decrease with increasing numbers of atoms in the excited molecules.  相似文献   

17.
A method of selecting molecules embedded in nanodroplets (clusters) of superfluid helium is proposed, which is based on the selective vibrational excitation of embedded molecules by intense IR laser radiation. This action leads to a significant decrease in size of the excited clusters, after which these clusters are separated with respect to size via scattering of the cluster beam on a crossing atomic beam. The method is described in detail and the possibility of selecting SF6 molecules in liquid helium nanodroplets using the excitation by CO2 laser radiation and the angular separation via scattering on a xenon atomic beam is demonstrated. The results show that, by using this technique, it is possible to separate molecules with respect to isotope (element) composition. Advantages and drawbacks of the method are analyzed.  相似文献   

18.
It has been found that molecules (e.g., SF6, CF3I) excited in a molecualr beam by intense infrared laser radiation into high vibrational states (with energy E v ≥ 0.5–2.0 eV) pass through a multichannel metal plate, which is cooled to T s ? 80–85 K and inclined to the beam axis, much more efficiently than unexcited (vibrationally cold) molecules. This property provides the possibility of separating excited and unexcited molecules in the beam. The method is described and the first experimental results are reported.  相似文献   

19.
The multiphoton-excited CF3Br molecules are investigated by the method of Raman light scattering spectroscopy at frequencies of overtones and compound vibrations. It is demonstrated that highly nonequilibrium energy distribution of molecules is formed under excitation. The physical parameters characterizing this distribution, including the part of excited molecules and their average excitation level, are determined. The pattern of vibrational energy distribution formed in the CF3Br molecules under multiphoton excitation is reconstructed.  相似文献   

20.
We investigate the potential of a single subwavelength aperture milled in an aluminium film to enhance the local electromagnetic field. We compare the Raman scattering of unadsorbed chlorobenzene molecules and the fluorescence emission of Cyanine-5 dyes, having the same excitation and collection setup for both experiments. For the optimal nanoaperture diameter, we report a clear enhancement factor of about 5 of the Raman scattering intensity per unit volume. Since Raman scattering probes the molecular vibrational levels and avoids the resonant pumping of a real excited state, the observed Raman enhancement is disconnected from the effects of the molecular energy levels alteration previously reported for fluorescent dyes. The observations are similar for both Raman and fluorescence experiments, and stand in good agreement with numerical electromagnetic computations of the excitation intensity inside the nanoaperture.  相似文献   

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