On the spectral line width broadening for simulation of the two-photon absorption cross-section of para-Nitroaniline in liquid environment

Autor(es)

Ramos, Tarcius N. ^[1] ; Silva, Daniel L. ^[2] ; Cabral, Benedito J. C. ^{[3, 4]} ; Canuto, Sylvio ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis, Rua Matao 1371, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Fed Sao Carlos, Dept Ciencias Nat Matemat & Educ, Rod Anhanguera Km 174, BR-13600970 Araras, SP - Brazil

^[3] Univ Lisbon, Fac Ciencias, Dept Quim & Bioquim, P-1749016 Lisbon - Portugal

^[4] Univ Lisbon, Fac Ciencias, Biosyst & Integrat Sci Inst BioISI, P-1749016 Lisbon - Portugal

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF MOLECULAR LIQUIDS; v. 301, MAR 1 2020.
• Citações Web of Science: 0

Resumo

The calculated two-photon absorption (TPA) cross-section amplitude depends on the spectral line width (Gamma) of the transition and there is not a consensus on the most appropriate way to obtain the Gamma value. Usually it is arbitrarily defined or ambiguously estimated based on experimental data or using a transition energy variation determined from a quantum mechanics/molecular mechanics approach. In this study we compare different procedures to estimate Gamma values and different methods of spectral convolution to simulate TPA cross-section for para-Nitroaniline (pNA) in liquid environment. The effects of the liquid environment on the nonlinear absorption were approximated using Monte Carlo and Born-Oppenheimer Molecular Dynamics as well as the commonly used Polarizable Continuum Model. The different procedures adopted here provided large difference in the calculated TPA amplitudes, mainly because of the underestimate/overestimate of the homogeneous and/or inhomogeneous contributions to the spectral line width. Based on these difficulties, we suggest a new procedure in which the value assigned to Gamma is the one used to induce the total line width of the simulated TPA spectrum to reproduce the experimental one-photon absorption line width. Within this procedure the Gamma value, which becomes a fitting parameter (Gamma(fit)), represents part of the homogeneous contribution to the spectral line width. Finally, although time dependent density functional theory calculations reproduced only reasonably well the energy of the lowest-energy pi -> pi{*} is transition of pNA, the fitting procedure here proposed provided the calculated TPA cross-section in good agreement with the available experimental data. (C) 2020 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 15/14189-3 - Espectroscopia de Absorção de Dois Fótons em Moléculas Orgânicas Incluindo Efeitos do Solvente
• Beneficiário: Tárcius Nascimento Ramos
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 15/20032-0 - Estudo das Propriedades Ópticas Não Lineares e de Transporte de Carga de Moléculas Multiramificadas via Métodos de Química Quântica.
• Beneficiário: Daniel Luiz da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Regular