Poullain S Marggi, Cireasa R, Cornaggia C, Simon M, Marin T, Guillemin R, Houver J C, Lucchese R R, Dowek D
Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France.
Phys Chem Chem Phys. 2017 Aug 23;19(33):21996-22007. doi: 10.1039/c7cp02057k.
We investigate the multiphoton ionization of NO using tunable (430-375 nm) femtosecond pulses and photoelectron-photoion coincidence momentum spectroscopy. In order to understand the complex electronic and nuclear photodynamics at play following absorption of three to five photons, we also report extended photoionization calculations using correlated targets and coupled channels. Exploring the multiphoton dissociative ionization (MPDI) and multiphoton ionization (MPI) processes over such a broad energy range enables us to lend further support to our work carried out around 400 nm of a femtosecond laser [S. Marggi Poullain et al., J. Phys. B: At., Mol. Opt. Phys., 2014, 47, 124024]. Two excitation energy regions are identified and discussed in terms of the proposed reaction pathways, highlighting the significant role of Rydberg states, such as the [R*(6a), 3pσ] Rydberg state, in the NO multiphoton excitation and photoionization. These new results support our previous assumption that different bent and linear geometries of the NO(XΣ) ionic state contribute to the MPDI and MPI, consistent with the reported calculations which reveal an important vibronic coupling characterizing the photoemission. Remarkably, the strong anisotropy of the recoil frame photoelectron angular distribution (RFPAD) previously observed at 400 nm appears as a fingerprint across the whole explored photon energy range.
我们使用可调谐（430 - 375纳米）飞秒脉冲和光电子 - 光离子符合动量光谱研究了一氧化氮（NO）的多光子电离。为了理解在吸收三到五个光子后发生的复杂电子和原子核光动力学过程，我们还报告了使用相关靶和耦合通道的扩展光电离计算。在如此宽的能量范围内探索多光子解离电离（MPDI）和多光子电离（MPI）过程，使我们能够进一步支持我们在飞秒激光400纳米附近开展的工作[S. Marggi Poullain等人，《物理学报B：原子、分子和光学物理》，2014年，47卷，124024]。根据提出的反应途径确定并讨论了两个激发能区域，突出了里德堡态，如[R*(6a)，3pσ]里德堡态，在NO多光子激发和光电离中的重要作用。这些新结果支持了我们之前的假设，即NO(XΣ)离子态的不同弯曲和线性几何结构对MPDI和MPI有贡献，这与所报道的计算结果一致，这些计算揭示了表征光发射的重要振动 - 电子耦合。值得注意的是，先前在400纳米处观察到的反冲框架光电子角分布（RFPAD）的强烈各向异性在整个探索的光子能量范围内都表现为一个特征。
