+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Excitonic Splitting and Vibronic Coupling Analysis of the m-Cyanophenol Dimer

Excitonic Splitting and Vibronic Coupling Analysis of the m-Cyanophenol Dimer

Journal of Physical Chemistry. a 121(1): 73-87

The S1/S2 splitting of the m-cyanophenol dimer, (mCP)2 and the delocalization of its excitonically coupled S1/S2 states are investigated by mass-selective two-color resonant two-photon ionization and dispersed fluorescence spectroscopy, complemented by a theoretical vibronic coupling analysis based on correlated ab initio calculations at the approximate coupled cluster CC2 and SCS-CC2 levels. The calculations predict three close-lying ground-state minima of (mCP)2: The lowest is slightly Z-shaped (Ci-symmetric); the second-lowest is <5 cm-1 higher and planar (C2h). The vibrational ground state is probably delocalized over both minima. The S0 → S1 transition of (mCP)2 is electric-dipole allowed (Ag → Au), while the S0 → S2 transition is forbidden (Ag → Ag). Breaking the inversion symmetry by 12C/13C- or H/D-substitution renders the S0 → S2 transition partially allowed; the excitonic contribution to the S1/S2 splitting is Δexc = 7.3 cm-1. Additional isotope-dependent contributions arise from the changes of the m-cyanophenol zero-point vibrational energy upon electronic excitation, which are Δiso(12C/13C) = 3.3 cm-1 and Δiso(H/D) = 6.8 cm-1. Only partial localization of the exciton occurs in the 12C/13C and H/D substituted heterodimers. The SCS-CC2 calculated excitonic splitting is Δel = 179 cm-1; when multiplying this with the vibronic quenching factor Γvibronexp = 0.043, we obtain an exciton splitting Δvibronexp = 7.7 cm-1, which agrees very well with the experimental Δexc = 7.3 cm-1. The semiclassical exciton hopping times range from 3.2 ps in (mCP)2 to 5.7 ps in the heterodimer (mCP-h)·(mCP-d). A multimode vibronic coupling analysis is performed encompassing all the vibronic levels of the coupled S1/S2 states from the v = 0 level to 600 cm-1 above. Both linear and quadratic vibronic coupling schemes were investigated to simulate the S0 → S1/S2 vibronic spectra; those calculated with the latter scheme agree better with experiment.

Please choose payment method:

(PDF emailed within 0-6 h: $19.90)

Accession: 059714516

Download citation: RISBibTeXText

PMID: 28001398

DOI: 10.1021/acs.jpca.6b10416

Related references

Analysis of the S2←S0 vibronic spectrum of the ortho-cyanophenol dimer using a multimode vibronic coupling approach. Journal of Chemical Physics 142(8): 084308, 2016

Excitonic splitting, delocalization, and vibronic quenching in the benzonitrile dimer. Journal of Physical Chemistry. a 118(47): 11253-11261, 2015

Excitonic splitting and vibronic coupling in 1,2-diphenoxyethane: conformation-specific effects in the weak coupling limit. Journal of Chemical Physics 138(20): 204313, 2014

S(1)/S(2) excitonic splittings and vibronic coupling in the excited state of the jet-cooled 2-aminopyridine dimer. Journal of Chemical Physics 131(20): 204308, 2009

Vibronic coupling in cyclopentadienyl radical: a method for calculation of vibronic coupling constant and vibronic coupling density analysis. Journal of Chemical Physics 124(2): 024314, 2006

The S1/S2 exciton interaction in 2-pyridone·6-methyl-2-pyridone: Davydov splitting, vibronic coupling, and vibronic quenching. Journal of Chemical Physics 135(15): 154311, 2011

Vibronic coupling in naphthalene anion: vibronic coupling density analysis for totally symmetric vibrational modes. Journal of Physical Chemistry. a 112(4): 758-767, 2008

Regular and chaotic dynamics in systems with excitonic-vibronic coupling. Chaos, Solitons & Fractals 4(11): 2067-2075, 1994

Localization of electronic and vibrational energy in the jet-cooled m -cyanophenol/ o -cyanophenol dimer: laser induced fluorescence and fluorescence-dip Ir spectra. Molecular Physics 103(11-12): 1655-1662, 2005

Excitonic-vibronic coupled dimer: Separatrix structure, regular and chaotic behavior of the semiclassical dynamics versus full-quantum evolution. Journal of Luminescence 76-77: 530-533, 1998

Calculation of vibronic coupling constant and vibronic coupling density analysis. Journal of Molecular Structure 838(1-3): 116-123, 2007

Excitonic splitting and coherent electronic energy transfer in the gas-phase benzoic acid dimer. Journal of Chemical Physics 137(20): 204303, 2013

Vibronic coupling in benzene cation and anion: vibronic coupling and frontier electron density in Jahn-Teller molecules. Journal of Chemical Physics 124(15): 154303, 2006

Alignment, vibronic level splitting, and coherent coupling effects on the pump-probe polarization anisotropy. Journal of Physical Chemistry. a 115(16): 4101-4113, 2011

Vibronic-coupling effect on the paramagnetic Fe2+ ions in an insulator: Mössbauer quadrupole splitting in a biological system. Physical Review. B, Condensed Matter 46(2): 632-638, 1992