Naslov
An ab initio surface hopping dynamics study on the photodeactivation processes in protonated formamide

Autori
Antol, Ivana ; Vazdar, Mario ; Barbatti, Mario ; Eckert-Maksić, Mirjana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Electron correlation and molecular dynamics for excited states and photochemistry Symposium in honor of Hans Lischka´s 65th birthday : Book of Abstracts / Aquino, A. J. Adélia - Beč : Erwin Schrödinger Institute (ESI), 2008, 34-34

Skup
Electron correlation and molecular dynamics for excited states and photochemistry Symposium in honor of Hans Lischka´s 65th birthday

Mjesto i datum
Beč, Austrija, 03.07.2008. - 04.07.2008

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
surface hopping dynamics; formamide; photodeactivation process; protonation effect

Sažetak
Photoinduced fragmentation of charged small polypeptides has been intensively investigated in recent years due to their importance in ‘ soft’ ionization methods such as MALDI and ESI. These studies revealed that photofragmentation patterns depend strongly on the peptide composition, on electronic state excited by the photon (excitation of aromatic amino acid residues at 266 nm or amide chromophore of the peptide backbone at 193 or 157 nm), on the mass analyzer employed and its time regime. In this study, the protonated formamide will be used as a model molecule for analysis of photofragmentation of protonated peptide groups which do not incorporate an aromatic chromophore and in which excitation to low lying excited states takes place primarily at the C=O double bond of the amide moiety. The calculations were carried out using the multireference configuration interaction calculations with singles and doubles (MR-CISD) method while dynamics were simulated by employing the mixed quantum-classical direct trajectory method with surface hopping based on multi-configurational self-consistent wave functions. The photodeactivation from the first excited singlet state in O-protonated formamide resembled those found for the second valence excited state of the parent molecule. Two photodissociation processes were found: the C-N (major) and C-O (minor) dissociations with very short lifetimes (33 fs). Similarly, the major process for photodecomposition in the first excited state of N-protonated formamide resembles that for the parent formamide, and involves C-N dissociation with a lifetime around 390 fs. However, 55% of trajectories remained undissociated and undeactivated until 1000 fs, indicating existence of other deactivation processes on a longer time scale.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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