Two-photon states in squaraine monomers and oligomers

Scherer, Dieter; Dörfler, Robert; Feldner, Andreas; Vogtmann, Thomas; Schwoerer, M.; Lawrentz, Ulf; Grahn, Walter; Lambert, Christoph

doi:10.1016/s0301-0104(02)00384-1

Cited by 87 publications

(142 citation statements)

References 58 publications

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“…35 , for which we estimate ρ ≈ 0.3, with a TPA cross section of the order of 9.000 GM, in reasonable agreement with the reported one. This squaraine dye is then also placed in region II of the phase diagram in Figure 1, with no symmetry breaking phenomena in either the ground state or excited state.…”

Section: Highly-quadrupolar Symmetry-preserving Systemssupporting

confidence: 91%

“…As for TPA spectra in CHCl 3 we confirm results in Ref. 35 , with a maximum at 820 nm, even if the actual cross section is about 40% lower than reported in Ref. 35 (in which TPA measurements were conducted using nanosecond pumping).…”

Section: Highly-quadrupolar Symmetry-preserving Systemssupporting

confidence: 89%

“…35 , with a maximum at 820 nm, even if the actual cross section is about 40% lower than reported in Ref. 35 (in which TPA measurements were conducted using nanosecond pumping). Measurements in other solvents however suggest that the peak at 820 nm does not correspond to the maximum of the TPA band but that the TPA signal increases further in the region below 800 nm that, quite unfortunately, is not accessible with our experimental setup.…”

Section: Highly-quadrupolar Symmetry-preserving Systemsmentioning

confidence: 61%

“…70 For these chromophores only one study of two-photon absorption is available in the literature, reporting data collected with nanosecond excitation pulses. 35 To obtain more reliable data, we…”

Section: Highly-quadrupolar Symmetry-preserving Systemsmentioning

confidence: 99%

“…A large body of experimental data is available for many families of quadrupolar 5,7,[9][10][11]13,18,[33][34][35][36] and octupolar chromophores 15,17,18,34,[37][38][39][40][41][42][43][44][45] as well as for branched and dendritic systems. 16,40,43,44,46,47 Due to their highly symmetric structure, all these systems have no permanent dipole moment and of course vertical (unrelaxed) states are non-dipolar as well.…”

Section: Introductionmentioning

confidence: 99%

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Charge Instability in Quadrupolar Chromophores: Symmetry Breaking and Solvatochromism

et al. 2006

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We present a joint theoretical and experimental work aimed to understand the spectroscopic behavior of multipolar dyes of interest for nonlinear optics (NLO) applications. In particular, we focus on the occurrence of broken-symmetry states in quadrupolar organic dyes and their spectroscopic consequences. To gain a unified description, we have developed a model based on a few-state description of the charge-transfer processes characterizing the low-energy physics of these systems. The model takes into account the coupling between electrons and slow degrees of freedom, namely, molecular vibrations and polar solvation coordinates. We predict the occurrence of symmetry breaking in either the ground or first excited state. In this respect, quadrupolar chromophores are classified in three different classes, with distinctively different spectroscopic behavior. Cases of true and false symmetry breaking are discriminated and discussed by making resort to nonadiabatic calculations. The theoretical model is applied to three representative quadrupolar chromophores: their qualitatively different solvatochromic properties are connected to the presence or absence of broken-symmetry states and related to two-photon absorption (TPA) cross-sections. The proposed approach provides useful guidelines for the synthesis of dyes for TPA application and represents a general and unifying reference frame to understand energy-transfer processes in multipolar molecular systems, offering important clues to understand basic properties of materials of interest for NLO and energy-harvesting applications.

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Section: Highly-quadrupolar Symmetry-preserving Systemssupporting

confidence: 91%