Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study

IF 1.6 3区地球科学 Q2 MINERALOGY

Gems & Gemology Pub Date : 2020-08-01 DOI:10.5741/gems.56.2.258

Chunhui Zhoi, T. Tsai, Nicholas Sturman, Nanthaporn Nilpetploy, Areeya Manustrong, Kwanreun Lawanwong

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引用次数: 4

Abstract

GEMS & GEMOLOGY SUMMER 2020 Optical brightening agents (OBAs) are chemical compounds that can absorb light in the ultraviolet and violet region of the electromagnetic spectrum and emit light in the blue region as fluorescence, due to their extended conjugation and/or aromaticity. They are sometimes called fluorescent brightening agents or fluorescent whitening agents, and have been frequently used to enhance the appearance of fabric and paper (Lanter, 1966; Leaver and Milligan, 1984; Esteves et al., 2004; Bajpai, 2018). While many types of brighteners are listed in the Colour Index (https://colour-index.com), only a handful are commercially important. Some examples are shown in figure 1. Photoluminescence is light emission from any form of matter after the absorption of photons. Fluorescence is a type of photoluminescence in which a molecule dissipates its absorbed energy through the rapid emission of a photon, while phosphorescence is the emission of radiation in a similar manner to fluorescence but on a longer timescale, so that emission continues after excitation ceases. Fluorescence can be generated by exciting the substance via a range of energy sources. The molecule in the substance absorbs the source energy and once excited moves from a lower electronic state to a higher one. Immediately after absorbing energy, it loses the energy by emitting a photon; this process of photon emission is called luminescence. Typically, fluores-

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珍珠的光学增白增亮:荧光光谱研究

GEMS&GEMOLOGY SUMMER 2020光学增亮剂（OBAs）是一种化合物，由于其延长的共轭性和/或芳香性，可以吸收电磁光谱中紫外线和紫色区域的光，并在蓝色区域发出荧光。它们有时被称为荧光增白剂或荧光增白剂，并经常用于增强织物和纸张的外观（Lanter，1966；Leaver和Milligan，1984；Esteves等人，2004年；Bajpai，2018）。虽然颜色指数中列出了许多类型的增白剂(https://colour-index.com)，只有少数具有商业重要性。一些示例如图1所示。光致发光是任何形式的物质在吸收光子后发出的光。荧光是一种光致发光，分子通过光子的快速发射来耗散其吸收的能量，而磷光是以与荧光类似的方式但在更长的时间尺度上发射辐射，因此在激发停止后发射仍在继续。荧光可以通过一系列能量源激发物质而产生。物质中的分子吸收源能量，一旦被激发，就会从较低的电子态移动到较高的电子态。在吸收能量后，它立即通过发射光子来损失能量；这种光子发射的过程称为发光。通常，氟化物-

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来源期刊

Gems & Gemology 地学-矿物学

CiteScore

2.90

自引率

19.20%

发文量

期刊介绍： G&G publishes original articles on gem materials and research in gemology and related fields. Manuscript topics include, but are not limited to: Laboratory or field research; Comprehensive reviews of important topics in the field; Synthetics, imitations, and treatments; Trade issues; Recent discoveries or developments in gemology and related fields (e.g., new instruments or identification techniques, gem minerals for the collector, and lapidary techniques); Descriptions of notable gem materials and localities; Jewelry manufacturing arts, historical jewelry, and museum exhibits.