论文标题
使用固定多光子分子R-Matrix方法分析Rabitt时间延迟
Analysis of RABITT time delays using the stationary multi-photon molecular R-matrix approach
论文作者
论文摘要
我们采用最近开发的多光子R-Matrix方法来进行分子高于阈值光电离，以获得控制Rabitt实验干扰的二阶电离幅度。这使我们能够提取与该过程的非扰动时间依赖性模拟更好一致的Rabitt时间延迟，而不是通常使用的一阶（Wigner）延迟和渐近纠正的组合。我们计算分子框架以及h $ _2 $，n $ _2 $，co $ _2 $，h $ _2 $ o和n $ _2 $ o的h $ _2 $，n $ _2 $和n $ _2 $ o和n $ _2 $ o的延迟，并分析时间延迟的各种结构的起源，包括局部波浪交换的影响，形状交流，形状的共鸣和eNientrigation-eimentation-eimentation-eimentation-everigation。 Co $ _2^{+} $的B和C状态的时间延迟受到离子中第二个（IR）光子的吸收的强烈影响。此效果对应于其他贡献，即$τ_ {\ text {coupl}} $，对Rabitt的渐近近似延迟$τ\τ\τ_ {\ text {mol}}} +τ_{cc} +τ_{cc} +τ_{渐近理论的适用性取决于目标和IR光子能量，但通常始于XUV光子能量的30-35 eV。
We employ the recently developed multi-photon R-matrix method for molecular above-threshold photoionization to obtain second-order ionization amplitudes that govern the interference in RABITT experiments. This allows us to extract RABITT time delays that are in better agreement with non-perturbative time-dependent simulations of this process than the typically used combination of first-order (Wigner) delays and asymptotic corrections. We calculate molecular-frame as well as orientation-averaged RABITT delays for H$_2$, N$_2$, CO$_2$, H$_2$O and N$_2$O and analyze the origin of various structures in the time delays including the effects of partial wave interference, shape resonances and orientation-averaging. Time-delays for B and C states of CO$_2^{+}$ are strongly affected by absorption of the second (IR) photon in the ion. This effect corresponds to an additional contribution, $τ_{\text{coupl}}$, to the asymptotic approximation for the RABITT delays $τ\approx τ_{\text{mol}} +τ_{cc} + τ_{\text{coupl}}$. Applicability of the asymptotic theory depends on the target and IR photon energy but typically starts at approximately 30 -- 35 eV of XUV photon energy.
