Franck-Condon simulation for unraveling vibronic origin in solvent enhanced absorption and fluorescence spectra of rubrene

Ying Hu, Chen Wen Wang, Chaoyuan Zhu*, Fenglong Gu, Sheng Hsien Lin

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Quantum chemistry calculations at the level of (TD)-DFT plus PCM solvent models are employed for analyzing potential energy surfaces and as a result two local minima with D2, two local minima with C2H, and one second-order transition state with D2H group symmetry are found in both ground S0 and excited-state S1 potential energy surfaces. Simulated vibronic coupling distributions indicate that only second-order transition states with D2H group symmetry are responsible for observed absorption and fluorescence spectra of rubrene and vibrational normal-motions related with atoms on the aromatic backbone are active for vibronic spectra. The Stokes shift 1120 cm−1 (820 cm−1) and vibronic-band peak positions in both absorption and fluorescence spectra in non-polar benzene (polar cyclohexane) solvent are well reproduced within the conventional Franck-Condon simulation. By adding damped oscillator correction to Franck-Condon simulation, solvent enhanced vibronic-band intensities and shapes are well reproduced. Four (three) normal modes with vibration frequency around 1550 cm−1 (1350 cm−1) related to ring wagging plus CC stretching and CH bend motions on the backbone are actually interpreted for solvent enhanced absorption (fluorescence) spectra of rubrene in benzene and cyclohexane solutions.

Original languageEnglish
Pages (from-to)12407-12418
Number of pages12
JournalRSC Advances
Volume7
Issue number20
DOIs
StatePublished - 1 Jan 2017

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