Degenerate two-photon absorption in all-trans retinal: nonlinear spectrum and theoretical calculations.
In this work we investigate the degenerate two-photon absorption spectrum of all-trans retinal in ethanol employing the Z-scan technique with femtosecond pulses. The two-photon absorption (2PA) spectrum presents a monotonous increase as the excitation wavelength approaches the one-photon absorption band and a peak at 790 nm. We attribute the 2PA band to the mixing of states (1)B(u)(+)-like and |S(1)>, which are strongly allowed by one- and two-photon, respectively. We modeled the 2PA spectrum by using the sum-over-states approach and obtained spectroscopic parameters of the electronic transitions to |S(1)>, |S(2)> ("(1)B(u)(+)"), |S(3)>, and |S(4)> singlet-excited states. The results were compared with theoretical predictions of one- and two-photon transition calculations using the response functions formalism within the density functional theory framework with the aid of the CAM-B3LYP functional.
Vivas
M G
MG
Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, SP.
Silva
D L
DL
Misoguti
L
L
Zaleśny
R
R
Bartkowiak
W
W
Mendonca
C R
CR
D000042:Absorption; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D017785:Photons; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry*; D013057:Spectrum Analysis
D012172:Retinaldehyde