UNIGE document Scientific Article
previous document  unige:3319  next document
add to browser collection
Title

A theoretical study of the lowest electronic states of azobenzene: the role of torsion coordinate in the cis-trans photoisomerization

Authors
Orlandi, Giorgio
Bernardi, Fernando
Cembran, Alessandro
Garavelli, Marco
Published in Theoretical Chemistry Accounts. 2004, vol. 111, no. 2-6, p. 363-372
Abstract In the present paper we report the results of a multiconfigurational computational study on potentialenergy curves of azobenzene along the NN twisting to clarify the role of this coordinate in the decay of the S2(ππ*) and S1(nπ*) states. We have found that there is a singlet state, S3 at the trans geometry, on the basis of the doubly excited configuration n2π*2, that has a deep minimum at about 90°of twisting, where it is the lowest excited singlet state. The existence of this state provides an explanation for the short lifetime of S2(ππ*) and for the wavelength-dependence of azobenzene photochemistry. We have characterized the S1(nπ*) state by calculating its vibrational frequencies, which are found to correspond to the recently observed transient Raman spectrum. We have also computed the potential-energy curve for the triplet T1(nπ*) at the density functional theory B3LYP level, which indicates that in this state the isomerization occurs along the twisting coordinate.
Keywords AzobenzeneExcited electronic statesPhotoisomerizationMulticonfigurational wave function methods
Identifiers
Full text
Structures
Research group Groupe Gagliardi
Citation
(ISO format)
GAGLIARDI, Laura et al. A theoretical study of the lowest electronic states of azobenzene: the role of torsion coordinate in the cis-trans photoisomerization. In: Theoretical Chemistry Accounts, 2004, vol. 111, n° 2-6, p. 363-372. https://archive-ouverte.unige.ch/unige:3319

211 hits

156 downloads

Update

Deposited on : 2009-09-21

Export document
Format :
Citation style :