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The angular distributions of CO^+ from the dissociation of CO2^2+ and CO2^+ in intense femtosecond laser fields (45 fs, about 5 × 10^15 W/cm^2) are studied at a laser wavelength of 800nm based on the time-of-flight mass spectra of CO^+ fragment ions. The experimental results show that structural deformation occurs in the charge state of CO2^2+ and the CO^+ maintains linear geometrical structure. 相似文献
2.
近年来在可见光谱范围内已经把激光脉冲压缩到接近一个光学周期(2~3 fs)的物理极限,几fs的时间分辨精度可以描述分子化学反应过程,但是要探测远小于可见光周期的电子跃迁过程则需要阿秒(as)量级的光脉冲。利用脉冲间具有相同载波包络相位的阿秒脉冲序列能把可见光波段的光学频率梳向极紫外波段扩展;利用电子和离子碰撞复合过程短于一个光周期这个时间窗,通过测量激光场椭圆极化率对电子轨迹的微扰实现了as精度的分辨率;通过测量碰撞复合过程中的高能电子的辐射谱可以重构阿秒X光脉冲以及探测强场下束缚态和连续态电子动力学。 相似文献
3.
Role of highest occupied molecular orbitals in molecular field-free alignment by a femtosecond pulse 下载免费PDF全文
This paper studies the molecular rotational excitation and
field-free spatial alignment in a nonresonant intense laser field
numerically and analytically by using the time-dependent Schr?dinger
equation. The broad rotational wave packets excited by the
femtosecond pulse are defined in conjugate angle space, and
their coefficients are obtained by solving a set of coupled linear
equations. Both single molecule orientation angles and an ensemble
of O2 and CO molecule angular distributions are calculated in
detail. The numerical results show that, for single molecule highest
occupied molecular orbital (HOMO) symmetry σ tends to have a
molecular orientation along the laser polarization direction and
the permanent dipole moment diminishes the mean of the orientation angles; for
an ensemble of molecules, angular distributions provide more complex
and additional information at times where there are no revivals in
the single molecule plot. In particular, at the revival peak
instant, with the increase of temperature of the molecular ensemble, the
anisotropic angular distributions with respect to the laser polarization
direction of the π g orbital gradually transform to the
symmetrical distributions regarding the laser polarization vector and
for two HOMO configurations angular distributions of all directions
are confined within a smaller angle when the temperature of the molecular
ensemble is higher. 相似文献
4.
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
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