Department of Physics, University of Gothenburg, 41296 Gothenburg, Sweden.
J Chem Phys. 2011 Dec 7;135(21):214310. doi: 10.1063/1.3663618.
To clarify the ionization mechanism of large molecules under multi-photon ionization conditions, photo-electron spectroscopic studies on anthracene have been performed with electron imaging technique. Electron kinetic energy distributions below a few eV reveal that three kinds of ionization channels coexist, viz., vertical ionization, ionization from Rydberg states, and thermionic hot electron emission. Their relative yield is determined by the characteristic of the laser pulse. The duration in particular influences the ratio between the first two processes, while for higher intensities the last process dominates. Our results provide strong evidence that internal conversion plays an important role for the ionization of the molecule.
为了阐明多光子电离条件下大分子的电离机制，我们采用电子成像技术对蒽进行了光电子能谱研究。在几电子伏特以下的电子动能分布表明，三种电离通道共存，即垂直电离、里德堡态电离和热电子热发射。它们的相对产率取决于激光脉冲的特性。特别是持续时间影响前两个过程的比例，而对于更高的强度，最后一个过程占主导地位。我们的结果为分子的电离过程中内转换起着重要作用提供了有力的证据。
