Composition, Structural and Optical Properties of Golden Grass

Author(s):Show less -

Francis David, Denis Gilbert ^[1] ; Bargiela, Pascal ^[2] ; Santos da Silva, Marcus Vinicius ^[1] ; Godet, Christian ^[3] ; da Silva Santana, Victor Mancir ^[1] ; Santos Oliveira Magalhaes, Erick Rohan ^[1] ; da Luz, Leonis L. ^[4] ; Alves, Jr., Severino ^[4] ; Diniz Chubaci, Jose Fernando ^[5] ; Baffa, Oswaldo ^[6] ; da Silva, Antonio Ferreira ^{[1, 5]}

Affiliation

^[1] Univ Fed Bahia, Inst Fis, Campus Ondina, BR-40210340 Salvador, BA - Brazil

^[2] Univ Fed Bahia, Inst Quim, Campus Ondina, BR-40170115 Salvador, BA - Brazil

^[3] Univ Rennes 1, Inst Phys Rennes UMR 6251, CNRS, F-35042 Rennes - France

^[4] Univ Fed Pernambuco, Lab Terras Raras BSTR, Av Prof Moraes Rego 1235 Cidade Univ, BR-50670901 Recife, PE - Brazil

^[5] Univ Sao Paulo, Inst Fis, Lab Cristais Ion Filmes Finos & Datacao, BR-05508090 Butanta, SP - Brazil

^[6] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto FF, Dept Fis DF, Av Bandeirantes 3900, BR-14040901 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: Brazilian Journal of Physics; v. 52, n. 1 FEB 2022.
• Web of Science Citations: 0

Abstract

Golden grass is a vegetal fiber used in arts and crafts for its peculiar optical properties, namely, its shiny golden-like reflectivity. Since vegetal fiber structure is usually heterogeneous, complementary techniques have been used to understand the electronic properties of the external and core regions of golden grass fibers. The composition and dielectric function of the few nanometer-thick external surfaces has been investigated using X-ray photoelectron spectroscopy and energy loss spectroscopy (XPS-PEELS), while a comparison of vibrational and optical properties of the few-micron-thick external and fiber core regions was derived from Raman, optical, photoluminescence (PL) and photoacoustic (PAS) spectroscopies. Raman signature and valence-band distribution indicate that the internal and external parts of the fibers are made of some oxygen-depleted lignin-like carbonaceous material. Besides a plasmon peak at 21 eV, two main absorption bands at 3.7 eV and 8.2 eV have been identified as pi-pi{*} and sigma-sigma{*} electronic transitions at aromatic moieties. PL excitation and emission behavior confirm heterogeneous molecular structures at the core and external regions. Specular reflectance spectra calculated from the complex refractive index (derived from XPS-PEELS) do not explain the shiny golden-like aspect of golden grass, which may arise from diffuse reflectance within a collection of heterogeneous hollow fibers. (AU)

• FAPESP's process: 13/07699-0 - Research, Innovation and Dissemination Center for Neuromathematics - NeuroMat
• Grantee: Oswaldo Baffa Filho
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC