Electronic and Vibrational Structure of Bucky Bowl

Abstract

Bucky bowl is the molecule of nonplanar polycyclic aromatic hydrocarbons. We analyzed the vibronic sructure in the S 1 ← S 0 fluorescence excitation spectra of jet-cooled sumanene and corannulene. The spectrum is congested with a large number of vibronic bands, which are mostly assigned to out-of-plane vibrational modes. The S 1 state of corannulene is identified to 1 E 2 by the normal mode analysis, which is consistent with the result of SAC-CI calculation. The excitation energy of 1 A 2 state was lower than that of the 1 E 2 state by the TD-DFT method. The isolated corannulene molecule is considered to be a normal pentagon with considerable out-of-plane distortion (C 5v ).We observed the IR spectrum of corannulene in solid para-H 2 , which also indicates that the moelcule has a structure with five-fold symmetry in the S 0 state. We found the IR bands originated from protonated corannulene molecules, which are produced by the chemical reaction with a proton.