運用電磁理論與生物實驗探討植物光合作用結構的光學特性

Using Electromagnetic Theory and Biological Experiments to Study the Optical Properties of Photosynthesis Structures in Plants

張孝邦(Shiou-Pang Chang)

指導教授 ： 李佳翰

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10772

摘要

光合作用是地球上植物獲取太陽能量的最初始的機制，且是對所有生物而言最重要的生化反應。植物可以藉由光合作用以有效率的方式以
花費低廉的能量吸收太陽光之能量。在葉綠體中，葉綠餅是一個圓柱狀結構由數層囊狀膜堆疊而成，此結構可視為是一個可以吸收太陽光之繞射元件，堆疊的囊狀膜可視為光的波導或共振腔，直徑及堆疊層數是葉綠餅吸收特定波長的兩個重要參數。我們採用的植物為菸草，為了解其葉綠餅之繞射特性，我們進行電磁模擬與生物實驗。利用紅光LED (波長640 nm)、綠光LED (波長520 nm)、藍光LED (波長460 nm)和三色光混合LED燈設置了四個不同的光生長環境。利用穿透式電子顯微鏡所得到顯微結構圖，我們對不同光照條件下的變異數作統計
分析比較。為了解不同結構參數的葉綠餅在不同波長下的傳遞模態，利用時域有限差分法與有限元素法等兩種模擬方法來計算葉綠餅的電場分布和吸收能量。我們的研究結果將可以提供為解釋光合作用中植物葉綠餅之光學繞射行為的依據，我們建立之物理模型可作為未來獲取太陽光能之仿生設計元件的基礎。

關鍵字

光合作用 ； 時域有限差分法 ； 有限元素法 ； 生物光子學 ； 葉綠餅 ； 囊狀膜

並列摘要

Photosynthesis of plants is the primary sun energy harvesting mechanism on the earth, and it is one off the most important and efficient bio-chemical reactions for all features. Grana is a cylindrical structure stacked by layers of thylakoid membranes in chloroplasts and it can be seen as an diffractive optical element which can catch light energy. Furthermore, the stacked membranes are like the waveguides or resonators for light. The diameter and stacked number of grana are two important key parameters for specific wavelength light absorption. The tobacco is chosen for our study. To explain its optical diffraction characteristics, we use electromagnetic simulation and take the biology experiments. We set four light conditions using different LEDs (light emitting diodes), which are red LED (wavelength 640 nm), green LED (wavelength 520 nm), blue LED (wavelength 460 nm), and mixed light treatments. The TEM (Transmission Electron Microscopy) photos are taken and the statistics analyses are given. To know the modes in the grana with different structure parameters for different light wavelength, FDTD (Finite-Difference Time-Domain) and FEM (finite Element Method) simulations were used to calculate the fields and absorbed energy of different grana structures. Our results can be used to explain the optical diffraction characteristics of chloroplasts in plants during photosynthesis, and the physical modeling we established forms the basis to design biomimetric devices for solar energy harvesting in the future.

並列關鍵字

photosynthesis ； finite-difference time-domain ； finite element method ； biophotonic ； grana ； thylakoid

參考文獻

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