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21.
A four-state model considering the relative velocity distribution function for calculating the cross section of laserinduced collisional energy transfer in a Sr-Li system is presented and profiles of laser-induced collision cross section are obtained.The resulting spectra obtained from different intermediate states are strongly asymmetrical in an opposite asymmetry.Both of the two intermediate states have contributions to the final state,and none of the intermediate states should be neglected.The peak of the laser-induced collisional energy transfer(LICET) profile shifts toward the red and the FWHM becomes narrower obviously with laser field intensity increasing.A cross section of 1.2 × 10-12 cm 2 at a laser field intensity of 2.17 × 10 7 V/m is obtained,which indicates that this collision process can be an effective way to transfer energy selectively from a storage state to a target state.The existence of saturation for cross section with the increase of the laser intensity shows that the high-intensity redistribution of transition probabilities is an important feature of this process,which is not accounted for in a two-state treatment. 相似文献
22.
以现有的激光感生碰撞能量转移的四能级理论模型为基础,通过直接积分态振幅的运动方程,对弱场、强场两种情况下Ba-Sr系统的激光感生碰撞能量转移过程进行了数值计算,得到了两种情况下的激光感生碰撞跃迁概率和碰撞截面的谱线线型.在弱场情况下的数值计算结果与近似解析解的计算结果符合很好.对强场情况下的数值积分计算结果表明:激光感生碰撞作用随转换激光强度的增大而增强;强场时激光感生碰撞截面谱线的峰值位置明显偏离了共振频率并向紫端移动,且碰撞截面谱线的半宽度(即调谐范围)较之弱场明显变小.
关键词:
激光感生碰撞能量转移
碰撞截面
Ba-Sr系统
强场 相似文献
23.
Solid-state samples based on modified polymethyl methacrylate (MPMMA) with methanol doped with the dye pyrromethene 650 (PM650) are prepared.The effects of a volume percentage of methanol on the laser characteristics of the sample,including spectra properties,slope efficiency,photostability and tunable properties,are investigated.The broadband dye laser output wavelength is around 655 nm and a highest slope efficiency of 32.23% is achieved.Pumping the samples at a repetition rate of 5 Hz with a pulse energy of as high as 100 mJ (the fluence is 0.26 J/cm 2),the longest lifetime (168000 shots) is obtained in the sample (MMA:methanol=18:2),and the corresponding normalized photostability reaches 109.19 GJ/mol.When the sample (MMA:methanol=18:2) is placed in a Shoshan-type oscilla-tor,the narrow-linewidth operation is a continuous tuning range (up to 64 nm).The results indicate that the laser characteristics of solid-state dyes can be greatly enhanced by using modified PMMA with methanol serving as the solid host. 相似文献
24.
We present a valence orbital method of calculating
high-order harmonic generation from a diatomic molecule with arbitrary
orientation by using a space rotation operator. We evaluate the
effects of each valence orbital on harmonic emissions from N2
and O2 molecules in detail separately. The calculation
results confirm the different properties of harmonic yields from
N2 and O2 molecules which are well consistent with available
experimental data. We observe that due to the orientation dependence
of \sigma and \pi orbitals, the bonding orbital (\sigma
_{2pz} )^2 of N2 determines the maximum of harmonic emission
when the molecular axis of N2 is aligned parallel to the laser
vector, and the magnitude of the high harmonic signal gradually
weakens with the orientation angle of molecular axis increasing. But
for O2 molecule the antibonding orbitals (\pi _{2py}^\ast )^1
and (\pi _{2pz}^\ast )^1 contribute to the maximum of harmonic
yield when O2 is aligned at 45^{\circ} and bonding orbitals
(\pi _{2py} )^2 and (\pi _{2pz} )^2 slightly influence the
orientation angle of maximum of harmonic radiation not exactly at
45^{\circ}. 相似文献