H2的振动及转动受激喇曼散射研究

本文研究了不同泵浦光偏振态及氢气气压时,氢的振动及转动受激喇曼散射的竞争效应.在5atm的氢喇曼池中,以波长为532nm的椭偏激光为泵浦源,当椭圆的压缩系数为tg26°～tg32°时,获得了60多条Q(1)和S(1)混合谱线.并在低压氢及线偏或准线偏光泵浦条件下,观察到迄今尚未见报道的受激R(1)喇曼谱线.     

双折射光纤受激喇曼散射的研究

本文详细地研究了双折射光纤的受激喇曼散射.观测到9级斯托克斯受激喇曼谱.文中讨论和测试了阈值和频移与泵浦光偏振方向间的关系;当泵浦光偏振方向与光纤椭圆核的长轴或短轴平行时的传输损耗.并根据测得的阈值在理论上计算了各级斯托克斯线的喇曼增益系数.     

紫外激光离解四氯化钛产生的钛原子的受激喇曼散射

紫外激光(259—300nm)离解四氯化钛产生了大量钛原子,它们主要处于钛原子的基态a³F₂和亚稳态a³F_3,4上。通过近共振跃迁对处于a³F_2,3,4态上的钛原子进行泵浦,观测到一系列钛原子的受激喇曼散射和受激辐射,并对所有谱线进行了认证。钛原子的受激喇曼散射的脉宽和时间分辨谱表明,紫外激光离解四氯化钛产生钛原子的过程非常迅速,估计所需时间≤1ns。 关键词：     

单纵模Nd:YAG激光泵浦H2气中的受激喇曼散射

用单纵模Nd:YAG激光(波长1.06μm,脉宽9ns,线宽0.003cm-1)泵浦氢气中的受激喇曼散射,产生很强的后向一级斯托克斯.当泵浦能量为120mJ,压力为1.5MPaH2时,后向和前向喇曼的光子转化效率分别为66%和15%,而在4MPa时两个数值分别为46%和39%.由于后向喇曼与前向喇曼和泵浦光的传播方向相反,二者的相互竞争产生了张弛振荡,使得后向和前向喇曼的时间波形都分裂为两个峰,后向喇曼的两个峰都被压窄到1ns,使峰值功率达到了泵浦光功率的二倍,这在前向喇曼是不可能的.而且后向喇曼的光束质量要大大优于泵浦光和前向喇曼的光束质量,在4MPaH2和脉冲重复频率为10Hz时,喇曼过程的放热使前向喇曼的光束质量变坏,但对后向喇曼的光束质量影响不大.计算表明,该实验条件下受激喇曼过程没有达到稳态,所有实验结果都可以而且只能用相关的瞬态受激喇曼理论解释.     

鉴别CS2介质受激喇曼散射和受激布里渊散射阈值的微小差异的实…

本文提出一个测试ＣＳ２介质受激喇曼散射和受激布里渊散射阈值的微小差异的实验方法，并成功地获得阈值稍低的受激喇曼散射，而抑制了受激布里渊散射。     

高压氢激发态之间的受激喇曼散射

本文采用非稳腔输出的XeCl准分子激光,首次观察到高压氢高激发态之间的受激喇曼散射,并讨论了它们产生的条件.     

金属蒸气受激喇曼散射的原子基态抽空效应

将受激Raman散射原子基态及终态粒子数变化的速率方程与聚焦的泵浦光束及喇曼光束功率变化的微分方程组联立并进行数值求解;研究了金属蒸气受激Raman散射过程中基态粒子数的抽空现象及其对Raman能量转换过程的影响。     

LDS751染料的受激喇曼散射

报道了用532nm激光抽运LDS751染料产生720—780nm可调谐染料激光输出的同时,观察到喇曼频移为102和45cm-1的反斯托克斯线,前者谱线较强,后者较弱.与这两条强线对应的斯托克斯线未能观察到.另外,还观察到喇曼频移为34cm-1的一级和二级斯托克斯线与反斯托克斯线 关键词： LDS751染料 受激喇曼散射 喇曼位移 斯托克斯线 反斯托克斯线     

CBrCl3液芯光纤中的受激喇曼散射

以1.06μm调Q-锁模激光泵浦CBrCl_3液芯光纤,观察到11级受激喇曼散射,测量了各级受激喇曼散射的相对峰值功率及第9、10和11级的频谱.这种液芯光纤中的受激喇曼散射可作为获得2μm以上波段红外相干光的手段.     

转动喇曼散射截面的群论计算

本文利用群链U(4)U(3)O(3)描述双原子分子N_2和O_2振转谱的对称性质,并利用群论方法计算了N_2和O_2分子转动喇曼散射的跃迁矩阵元,给出了它们的转动喇曼散射的截面。结果与实验较好地符合。     

三原子分子的喇曼散射

利用U(5)群链描述三原子分子振转谱的对称性质,并用群论方法计算了CO_2分子喇曼散射的跃迁矩阵元,给出了它的振动与转动喇曼散射截面.结果与实验较好地符合.     

Picosecond stimulated Raman scattering of BaWO4 crystal

In single-pass configuration, a picosecond pulse laser was used to investigate the stimulated Raman scattering in different BaWO₄ crystals. Using the thresholds for the first Stokes line along the a- and c-axis, the Raman gain coefficients of the BaWO₄ crystals were calculated along their respective direction. The higher Stokes (fourth) and anti-Stokes (third) lines were observed. Compared with other well-known Raman crystals, such as KGd(WO₄)₂ and Ba(NO₃)₂, BaWO₄ has favorable properties for scattering the pump radiation with picosecond pulse duration. The Raman gain coefficients of BaWO₄ are different, but do not vary for different transmission directions, which means that this Raman material can be selected more freely.     

Elastic differential cross sections of electron scattering by CF_4 at intermediate energies

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Elastic differential cross sections of electron scattering by CF_4 at intermediate energies

The elastic differential cross sections(DCS)for electron scattering from CF 4 are calculated at six impact energies(in 100—700 eV)employing the independent atom model(IAM)with partial waves. The atoms are presented by a model complex optical potential which is composed of static, exchange, polarization, and absorption terms. The electron density function ρ(r) is obtained by a fitting procedue to the Dirac Hartree Fock Slater sef consistent data. Compared with available experimental data, the presen...     

Inelastic neutrino scattering off stable even-even Mo isotopes at low and intermediate energies

Inelastic neutrino scattering cross sections for the even-even Mo isotopes (contents of the MOON detector at Japan), at low and intermediate electron neutrino energies (?_i≤100 MeV), are calculated. MOON is a next-generation double beta and neutrino-less double-beta-decay experiment which is also a promising facility for low-energy neutrino detection. The nuclear wave functions required in this work have been constructed in the context of the quasi-particle random phase approximation (QRPA) and the results presented refer to , , , and isotopes.     

He-HF体系势能模型对散射截面影响的理论研究

用BFW势函数拟合在CCSD(T)/aug-cc-pVQZ理论水平下计算的He-HF相互作用能，获得了He原子与HF分子相互作用的各向异性势，并与其他势模型进行比较，验证了拟合势的可靠性；然后采用量子密耦(Close-Coupling)方法分别计算了He-HF碰撞体系在五种不同势能模型下的微分散射截面、分波散射截面和总截面，并对计算结果进行了详细的比较和分析.研究表明：势能球平均零点能位置、势阱深度、排斥势的强度以及势能在势阱附近的方向性都对散射截面有较大影响. 关键词： 势能模型 密耦方法 散射截面     

Continuous wave stimulated Raman scattering of benzene by fluorescence enhancement in hollow fused silica fiber

We present continuous wave stimulated Raman scattering (SRS) of benzene (C₆H₆) influenced by the fluorescent dye m‐cresol purple in a hollow fused silica fiber (HFSF). Because of the transmission loss of the HFSF filled with C₆H₆, the SRS occurs when the Stokes gain equals the transmission loss, with the loss taken at the Stokes wavelength. The 992 cm⁻¹ stimulated Stokes line has been obtained at the pump wavelength 658 nm, which cannot be obtained at 532 nm because the Stokes wavelength (562 nm) does not locate in the transmission loss. Also, the pump power is 35 mW with m‐cresol purple which is much lower than 800 mW without the dye. The profile of the 992 cm⁻¹ stimulated Stokes is changed, and the weak shoulders of the profile are amplified by fluorescence. These results are expected to be of relevance in applications on the tunable Raman laser at new wavelengths. Copyright © 2011 John Wiley & Sons, Ltd.     

Positron scattering from alkaline-earth elements

The total (elastic + inelastic) cross sections fore ⁺ impact on alkaline-earth elements from Be to Ra are calculated by employing a complex spherical optical potential. This potential has static, polarization and absorption components. The positron energy range is from a few eV to several thousand eV. We have compared our elastic cross sections for Mg and Ca with the other available results and the agreement is good for energies above 100eV. We have also compared our absorption cross sections withe ⁻ ionization cross sections at high energies where our absorption cross sections are in good accord. We have made Bethe plots fore ⁺ scattering on these elements.     

Light scattering and absorption by densely packed groups of spherical particles

Light scattering by clusters of spheres is investigated using numerical light scattering simulations. We consider clusters with density of 0.1-30%. Simulations are carried out for various real part of refractive indices (i.e., 1.01, 1.10, 1.31, 1.60, and 2.00) and for two values of the imaginary part of the refractive index (0 and 0.01) of spheres in the cluster. All spheres in the cluster have the same size (kr=4, k=2π/λ, r is the radius of the sphere, λ is the wavelength of the incident light).The obtained results include behaviors of cross sections as functions of densities (up to 30%), investigation of the influence of multiple scattering inside the media on the cross sections, and influence of densities on phase matrix elements (PMEs) and parameters obtained from the PMEs such as the cross polarization ratio, degree of linear depolarization, entropy, etc.In addition, we also investigate the influence of particle size for the same total volume of the cluster on cross sections. The outer radius R of the cluster of spheres was constant and equal to 40/k in all calculations.