Prediction of the photoelectron spectra of C122 by computing Franck-Condon factors

Abstract

The computation of Franck-Condon factors plays a key role for unraveling vibronic spectra and nonradiative process of molecules. In this work the photoelectron spectra of C122 were predicted by computing Franck-Condon factors. The equilibrium geometries and harmonic vibrational frequencies of five allotropes of C60C2C60 with dumbbell structures, including their cations and anions, were calculated at the B3LYP/6-31G(d) level. To facilitate the computation of Franck-Condon factors, a prescreening process for selecting transitions with stronger intensities was developed. The efficiency was further improved by rearranging the order of normal mode as the larger the maximum vibrational quantum number, the higher the order. The photoelectron spectra of C122- → C122 + e- and C122 → C122+ + e- were simulated. The simulated spectra are distinct for each molecule, indicating that the five allotropes of C122 can be identified by the experiment of photoelectron spectroscopy.

Theoretical Study of the Negative Ion Photoelectron Spectrum of Cyclooctatetraene via Computation of Franck–Condon Factors

“…32 The same technique has been applied to correlate the vibrational modes between two electronic states by our group. 18 The calculated vibrational frequencies are generally in agreement between different approaches adopted. For example, taking the B3LYP results of COT − as reference, the agreement is within 1% for the other two DFT computations and within 6% for the three CAS computations.…”

“…The correlation is based on the rule that the larger the absolute value (or square) of the matrix element, the more similar the two vibrational modes, given that the Duschinsky matrix describes the mixing of normal modes between two states . The same technique has been applied to correlate the vibrational modes between two electronic states by our group …”

“…The signal of the ring-breathing mode, as observed by Wenthold et al, is not present in the simulated PES of Tokizaki et al On the other hand, it is unclear why the ring-inversion mode, as identified by Tokizaki et al, is not taken into account by Wenthold et al In short, both theoretical studies are only in partial agreement with the experimental PES of 3 COT. Using the approach developed by our group for computing FCFs, − we hope that the PES of 3 COT can be interpreted within a unified theoretical framework.…”

Reassignment of the Photoelectron Spectrum of Methylketene Using a Hybrid Model of Harmonic and Anharmonic Oscillators to Compute Franck–Condon Factors

“…In the past decade, we have developed some approaches for computing FCFs of harmonic oscillators. ,− The Duschinsky effect has been taken into account in our model for polyatomic molecules . Our harmonic model for computing FCFs has been successfully applied to the studies of the PES of some molecules. − However, the excitation energies computed by the harmonic model are usually larger than the experimental values.…”

Modification of Vibrational Parameters of a D∞h-Symmetric Triatomic Molecule in a Laser Plasma

“…Refs. [16,17] deal with the FCFs in fullerenes. For photoluminescence in solids, the FCFs were involved, e.g., in [18].…”