Evidence for the need of a non-Born—Oppenheimer description of excited-state hydrogen transfer

✍ Scribed by Andrzej L. Sobolewski; Wolfgang Domcke

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 531 KB
• Volume: 211
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)80055-t

✦ Synopsis

The HO-CH-CH-CH=NH (enol form) to O=CH-CH=CH-NH2 (keto form) excited-state isomerization of I-amino-3-propenal is considered as a model system for photo-induced intramolecular hydrogen (or proton) transfer. The potential energy surfaces of the electronic ground state as well as of the lowest nx* and mt* excited singlet states have been characterized by ab initio complete-active-space self-consistent-field and multireference configuration-interaction calculations. It is found that the nfl potential energy function exhibits a significant barrier along the proton-transfer reaction coordinate, while the LK* potential energy function is almost barrierless and intersects the nn' surface, providing a pathway for ultrafast photo-induced proton transfer. It is argued that consideration of nn*-Xx:' vibronic coupling is essential in understanding the photo-induced proton-transfer reaction.