Abstract
A strong S1-S2 vibronic coupling effect is observed in the time-resolved coherent anti-Stokes Raman spectroscopy (CARS) spectra originating from the first excited singlet state of diphenylhexatriene. As determined from picosecond CARS measurements, the excited state spectrum appears on a subpicosecond time scale. An extremely high excited state hyperpolarizability |γ|exicted state ≃ 3 × 10-31 is derived from a CARS line shape analysis and is attributed to the increased delocalization after excitation in accordance with semiempirical calculations of bond lengths. We observe two strongly frequency-broadened vibrations being upshifted with respect to the C=C double bond stretching region of the ground state and assign them to the totally symmetric C=C stretching motion of the chain. Both frequencies depend on the solvent polarizability, giving evidence of strong S1-S2 vibronic coupling in the lowest excited singlet states. We discuss a model of S1-S2 vibronic coupling via an asymmetric low frequency mode. According to this model a double-well potential for the respective vibrational coordinate is generated in the first excited singlet state, resulting in two frequencies originating from the same type of vibration.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4211-4217 |
| Number of pages | 7 |
| Journal | Journal of Physical Chemistry A |
| Volume | 104 |
| Issue number | 18 |
| State | Published - May 11 2000 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
Cite this
Strong S1-S2 Vibronic Coupling and Enhanced Third Order Hyperpolarizability in the First Excited Singlet State of Diphenylhexatriene Studied by Time-Resolved CARS. / Werncke, W.; Wachsmann-Hogiu, Sebastian; Pfeiffer, M.; Lau, A.; Kummrow, A.
In: Journal of Physical Chemistry A, Vol. 104, No. 18, 11.05.2000, p. 4211-4217.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Strong S1-S2 Vibronic Coupling and Enhanced Third Order Hyperpolarizability in the First Excited Singlet State of Diphenylhexatriene Studied by Time-Resolved CARS
AU - Werncke, W.
AU - Wachsmann-Hogiu, Sebastian
AU - Pfeiffer, M.
AU - Lau, A.
AU - Kummrow, A.
PY - 2000/5/11
Y1 - 2000/5/11
N2 - A strong S1-S2 vibronic coupling effect is observed in the time-resolved coherent anti-Stokes Raman spectroscopy (CARS) spectra originating from the first excited singlet state of diphenylhexatriene. As determined from picosecond CARS measurements, the excited state spectrum appears on a subpicosecond time scale. An extremely high excited state hyperpolarizability |γ|exicted state ≃ 3 × 10-31 is derived from a CARS line shape analysis and is attributed to the increased delocalization after excitation in accordance with semiempirical calculations of bond lengths. We observe two strongly frequency-broadened vibrations being upshifted with respect to the C=C double bond stretching region of the ground state and assign them to the totally symmetric C=C stretching motion of the chain. Both frequencies depend on the solvent polarizability, giving evidence of strong S1-S2 vibronic coupling in the lowest excited singlet states. We discuss a model of S1-S2 vibronic coupling via an asymmetric low frequency mode. According to this model a double-well potential for the respective vibrational coordinate is generated in the first excited singlet state, resulting in two frequencies originating from the same type of vibration.
AB - A strong S1-S2 vibronic coupling effect is observed in the time-resolved coherent anti-Stokes Raman spectroscopy (CARS) spectra originating from the first excited singlet state of diphenylhexatriene. As determined from picosecond CARS measurements, the excited state spectrum appears on a subpicosecond time scale. An extremely high excited state hyperpolarizability |γ|exicted state ≃ 3 × 10-31 is derived from a CARS line shape analysis and is attributed to the increased delocalization after excitation in accordance with semiempirical calculations of bond lengths. We observe two strongly frequency-broadened vibrations being upshifted with respect to the C=C double bond stretching region of the ground state and assign them to the totally symmetric C=C stretching motion of the chain. Both frequencies depend on the solvent polarizability, giving evidence of strong S1-S2 vibronic coupling in the lowest excited singlet states. We discuss a model of S1-S2 vibronic coupling via an asymmetric low frequency mode. According to this model a double-well potential for the respective vibrational coordinate is generated in the first excited singlet state, resulting in two frequencies originating from the same type of vibration.
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M3 - Article
VL - 104
SP - 4211
EP - 4217
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 18
ER -