Presentation Information
[B1-5]Red fluorescence matter distribution in prismatic layer of pearl oyster shell
○Arma Lukmanul Hakim1,2 (1.Graduate School of Science and Engineering, Ehime University, 2.Department of Mechanical Engineering, Hasanuddin University)
司会:中野博昭(九州大学)
Keywords:
Fluorescence,Prismatic layer,Pearl oyster
Molluscan shell consisted of nacre and prismatic layers demonstrates optical characteristics such as absorbing, transmitting and reflecting light. For instance, nacre of Haliotis glabra and Pinctada margaritifera show iridescent color due to interference and diffraction of light, whereas prismatic layers of Pinctada vulgaris emit red fluorescence under UV light. We investigated the red fluorescence matter and its distribution in prismatic layers of pearl oyster. Our shell samples were Pinctada vulgaris as one of the pearl oyster or well known as Persian lingah oyster. SEM-EDX and TG-DTA were utilized to characterize prismatic layers. TG-DTA curves of heat flow and weight loss of powdered prismatic layers sample show exothermic reactions started from 190 oC to 670 oC with ~7.1 % weight loss indicating burn out of organic substances. Excitation spectrum for red fluorescence determined by a spectrophotometer demonstrates a strong absorption band at 320–460 nm with a peak wavelength of 402 nm and four weak bands with peak wavelengths at 506, 542, 564, and 581 nm. This spectrum indicates that the fluorescent matter in the organic substances is porphyrin compound derivatives. By using a fluorescence microspectroscope, the cross section of prismatic layers shows red fluorescence forming lamellar pattern. The lamellar pattern consists of red and black parallel zones with a modulation of emission intensity. Elemental mapping results show that sulphur-rich zones occupy the prismatic layers in the black zones. This suggests that the sulphur-rich zones absorb the excitation blue light for the fluorescent porphyrin.
<a href="http://confit-fs.atlas.jp/customer/mmij2014b/pdf/B1-5.pdf" target="_blank"></a>
<a href="http://confit-fs.atlas.jp/customer/mmij2014b/pdf/B1-5.pdf" target="_blank"></a>