Kim Jeong Hyun, Lee Sang Hak, Song Jae Kyu
School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea.
J Chem Phys. 2009 Mar 28;130(12):124321. doi: 10.1063/1.3093032.
This study examined the anion clusters of pyrene (Py) by mass spectrometry, photoelectron spectroscopy, and theoretical calculations. The photoelectron spectra of Py(n)(-) (n=1-4) were obtained at various photon energies. A change in photodetachment wavelength resulted in a large change in the relative intensities of vibrational progression in the photoelectron spectra. It is proposed that the observed modulation of the Franck-Condon factors by the different photon energies reflects autodetachment via the excited states of anion. The photoelectron spectra of Py(n)(-) at 355 nm showed a broad band structure between the S(0) and T(1) states, which is also due to the autodetachment via a Feshbach resonance state. The photoelectron spectra of Py(2)(-) suggest the presence of a unique dimeric interaction between the two pyrene moieties, whereas the spectral features of Py(3)(-) are similar to those of Py(1)(-). The stable structures of Py(2)(-) and Py(3)(-) obtained by density functional theory calculations support the experimental findings, where different intermolecular interactions govern the stabilization of these two species.
本研究通过质谱、光电子能谱和理论计算对芘（Py）的阴离子簇进行了研究。在不同光子能量下获得了Py(n)(-)（n = 1 - 4）的光电子能谱。光解离波长的变化导致光电子能谱中振动进程的相对强度发生很大变化。有人提出，不同光子能量对弗兰克 - 康登因子的观测调制反映了通过阴离子激发态的自解离。Py(n)(-)在355 nm处的光电子能谱在S(0)和T(1)态之间显示出宽带结构，这也是由于通过费什巴赫共振态的自解离所致。Py(2)(-)的光电子能谱表明两个芘部分之间存在独特的二聚体相互作用，而Py(3)(-)的光谱特征与Py(1)(-)相似。通过密度泛函理论计算得到的Py(2)(-)和Py(3)(-)的稳定结构支持了实验结果，其中不同的分子间相互作用决定了这两种物质的稳定性。
