Photoelectron spectroscopy of pyrene anion clusters: Autodetachmentvia excited states of anion and intermolecular interactions in anion clusters

摘要

This study examined the anion clusters of pyrene (Py) by mass spectrometry, photoelectronspectroscopy, and theoretical calculations. The photoelectron spectra of Py_nˉ (n=1-4) wereobtained at various photon energies. A change in photodetachment wavelength resulted in a largechange in the relative intensities of vibrational progression in the photoelectron spectra. It isproposed that the observed modulation of the Franck–Condon factors by the different photonenergies reflects autodetachment via the excited states of anion. The photoelectron spectra of Py_nˉat 355 nm showed a broad band structure between theS_0andT_1states, which is also due to theautodetachment via a Feshbach resonance state. The photoelectron spectra of Py_2ˉ suggest thepresence of a unique dimeric interaction between the two pyrene moieties, whereas the spectralfeatures of Py_3ˉare similar to those of Py_1ˉ.The stable structures 2and obtained bydensity functional theory calculations support the experimental findings, where differentintermolecular interactions govern the stabilization of these two species.