Analysis of the S2←S0 vibronic spectrum of the ortho-cyanophenol dimer using a multimode vibronic coupling approach.
The S2←S0 vibronic spectrum of the ortho-cyanophenol dimer (oCP)2 is analyzed in a joint experimental and theoretical investigation. Vibronic excitation energies up to 750 cm(-1) are covered, which extends our previous analysis of the quenching of the excitonic splitting in this and related species [Kopec et al., J. Chem. Phys. 137, 184312 (2012)]. As we demonstrate, this necessitates an extension of the coupling model. Accordingly, we compute the potential energy surfaces of the ortho-cyanophenol dimer (oCP)2 along all relevant normal modes using the approximate second-order coupled cluster method RI-CC2 and extract the corresponding coupling constants using the linear and quadratic vibronic coupling scheme. These serve as the basis to calculate the vibronic spectrum. The theoretical results are found to be in good agreement with the experimental highly resolved resonant two-photon ionization spectrum. This allows to interpret key features of the excitonic and vibronic interactions in terms of nodal patterns of the underlying vibronic wave functions.
Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
Sabine
S
Kopec
Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
Philipp
P
Ottiger
Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
Samuel
S
Leutwyler
Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany.
Horst
H
Köppel
D003198:Computer Simulation; D019281:Dimerization; D006860:Hydrogen Bonding; D016018:Least-Squares Analysis; D016014:Linear Models; D008956:Models, Chemical; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D014732:Vibration
D010636:Phenols; C552841:2-cyanophenol