利用雷射光實驗研究溶液的折射率梯度

科展類別
臺灣國際科展
屆次
2003年
科別
物理科
學校名稱
國立嘉義高級中學
指導老師
李文堂、陳宏昌
作者
蘇桓誼
關鍵字
雷射光,折射率

摘要或動機

溶液和溶劑置於同一容器中,當溶質向上擴散時,會形成濃度梯度及\r
折射率梯度dn/dy,且dn/dy 對高度y 的關係圖會呈現隨著高度改變的現\r
象。\r
半徑r 的D形容器,下方置溶液,上方置溶劑,以雷射光照射容器的\r
平面部份時,雷射光沿著法線出射,受折射率梯度的作用而向下偏Ζ距\r
離,a 為容器至屏的距離,得到dn/dy=Z/ar 的關係式;改變雷射光的高\r
度y 可得dn/dy 圖。\r
以硫代硫酸那作實驗,其dn/dy-y 圖為以原始界面為對稱軸,因其擴\r
散係數不隨濃度改變;甘游水溶液的dn/dy-y 圖呈現不對稱,圖形的極\r
大值往甘油方偏,主要係因為甘油的擴散係數隨濃度的增大而減少。\r
我們成功第把不同時間對同一溶液的實驗結果予以模型化,得到的\r
dn/dy-y 曲線隨時間改變,並發現該曲線所涵蓋的面積為定值。\r
\r
The mixing in a vertical column between a pure liquid and a solution produced a concentration gradient, which in turn produced the refractive index gradient. As the solute particles diffused upward into the pure liquid, the gradient was generated by the varying solute concentration. The plot of the refractive index gradient versus vertical position y (dn/dy vs y) is found to be varied with time. A D-shape container of radius r is partly filled with denser solution, and partly filled with solvent which is on the top of solution. When laser beam enters perpendicularly to the flat surface of the container, the outgoing beam strikes the container at normal incidence, and deflected down a vertical distance Z by the refractive index gradient. We can get dn/dy=Z/ar, where a is the distance between the container and the screen,. By changing the vertical position (y) of laser beam, we can get the plot of dn/dy vs y. For a sodium thiosulfate-water solution, the trace of dn/dy vs y is symmetric with respect to the position of original boundary. Since the diffusion coefficient of sodium thiosulfate is independent of concentration. For the trace of dn/dy vs y of a glycerol-water solution, it will no longer be symmetric. A skewed curve which reaches its maximum position is displaced to the glycerol side, because the diffusion coefficient of glycerol is decreased with concentration. We have successfully modeled the time-dependent experimental gradient curves on the same solution. The trace of dn/dy vs. y at different time is found to keep the area constant.


「為配合國家發展委員會「推動ODF-CNS15251為政府為文件標準格式實施計畫」,以及 提供使用者有文書軟體選擇的權利,本館檔案下載部分文件將公布ODF開放文件格式, 免費開源軟體可至LibreOffice 下載安裝使用,或依貴慣用的軟體開啟文件。」

檔案名稱 檔案大小 格式
利用雷射光實驗研究溶液的折射率梯度 726 KB Adobe Reader(Pdf)檔案