Electronic and vibronic contributions to two-photon absorption of molecules with multi-branched structures

• DOI: 10.1063/1.1313559
• Publication Date: 2002-07-26T12:41:43Z
• Authors: Peter Macak; Yi Luo; Patrick Norman; Hans Ågren
• Keywords: 01 natural sciences; 0104 chemical sciences

The electronic and vibronic contributions to the two-photon absorption of a series molecules with multi-branched structures have been studied using ab initio response theory. The results indicate that the electronic coupling between different branches alone cannot explain the experimental finding of a strong enhancement of the two-photon absorption cross section over the single branch structure, whereas it is predicted that vibronic contributions can play an important role in this respect. It is shown that for multi-branched molecules the use of circularly polarized light can increase the two-photon absorption cross section by a factor of 1.5 over linearly polarized light excitation.