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Degenerate two-photon absorption spectra in azoaromatic compounds
Leonardo De Boni1, Lino Misoguti, Sergio C Zílio
1Departamento de Física e Ciência dos Materiais, Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970, São Carlos, SP, Brazil.
Summary
This study investigated degenerate two-photon absorption (2PA) in azoaromatic compounds using the Z-scan technique. Molecular symmetry influences 2PA peak observation, with resonance enhancement observed across all tested compounds.
Area of Science:
- Nonlinear Optics
- Photochemistry
- Materials Science
Background:
- Azoaromatic compounds are crucial in various optical applications.
- Understanding two-photon absorption (2PA) is vital for designing advanced optical materials.
- Previous studies on 2PA in azoaromatics are limited, especially concerning spectral characteristics.
Purpose of the Study:
- To systematically investigate the degenerate two-photon absorption (2PA) spectra of seven azoaromatic compounds.
- To correlate molecular structure, specifically symmetry, with 2PA behavior.
- To explore resonance enhancement effects in 2PA cross-sections.
Main Methods:
- Utilized the Z-scan technique with femtosecond laser pulses.
- Studied compounds in dimethyl sulfoxide solution.
- Covered spectral range from the absorption band edge up to 1100 nm.
Main Results:
- Observed 2PA peaks for pseudostilbene-type azo compounds at twice the linear absorption peak wavelength.
- Did not observe distinct 2PA peaks for symmetrical PAMINO and DIAMINO compounds.
- Confirmed resonance enhancement of 2PA cross-section in all investigated azoaromatic compounds.
Conclusions:
- Molecular symmetry plays a critical role in the observation of 2PA peaks in azoaromatic compounds.
- A perturbation theory-based model effectively describes the 2PA peak and nonlinear resonance enhancement.
- Findings provide a foundation for understanding and tailoring 2PA properties in azoaromatic systems.