摘要或動機

高二上學期化學第一章，就討論到電子組態及原子光譜，雖然課本上有美麗的光譜插圖，但是觀念還是覺得十分抽象。所以老師為了提高我們學習的興趣，在實驗課中教我們自製簡易分光器，實際去觀賞各種光源及有色溶液的光譜，觀賞過程我們發現下列的問題：（1）為何一般離子是帶狀光譜，而MnO₄^- 光譜卻像線光譜？（2）MnO₄^- （深紫）和Mn²⁺（幾近無色），兩者顏色差異很大。是否與Mn 離子是否單獨存在有關係？（3）而另外CrO₄^2- （黃）、Cr₂O₇^2- （橙）和Cr³⁺（深藍色），三者顏色差異，是否與MnO₄^- 和Mn²⁺原因類似？為了尋找這些答案，於是開始了這個題目研究的過程。這期間我們花了很多時間與方法，嘗試將肉眼觀察到的影像，在自設的簡單暗房中，將光柵卡在數位相機的鏡頭前，以腳架或翻拍架拍攝下來。另外我們也應用到高三上學期平衡常數測定實驗中比色法的觀念，以及物理學上單狹縫繞射的觀念，使課本中的理論與實驗研究相互結合！最後我們藉分光光譜儀測定各有色溶液的可見光吸收光譜，再去定量分析這些有色溶液的顏色深淺，並查閱相關的文獻資料。最後發現MnO₄^-應該是一種電荷傳遞的遷移，所引起特別深顏色的現象。




至於CrO₄^2-  、Cr₂O₇^2- 和Cr³⁺三者顏色比較上是否和MnO₄^-

和Mn²⁺一樣的情形？我們推測應該也是如此！初見Cr³⁺有很深的顏色時，的確嚇了一跳，不過最後我們還是從它們的可見光吸收光譜中發現：
CrO₄^2-  、Cr₂O₇^2- 在λ_max

的吸光度比Cr³⁺還要大！但是為何肉眼觀察到的Cr³⁺顏色會比較深？那是因為我們視覺上對藍綠色比較敏感的緣故！請參考表一。




We have discussed some electronic configurations and atomic spectrums in chemistry
class. Although there were a few beautiful spectrums in textbook , but it’s difficult
to understand. So we made a simple spectroscope by ourselves to observe spectrums
of different light source and color solution . After some observation we have found
some problems below ：

（1）Why the spectrum of color solution is band spectrum , but the spectrum of permanganate
ion (MnO₄^- ) like line spectrum？


（2）MnO₄^- （deep purple）and Mn2＋（pink）, their color are different
very much. Is it because of the lone existence and binding with oxygen atom of manganese
ion?


（3）Additionally CrO₄^2-  （yellow）、Cr₂O₇^2- 

（orange）、Cr³⁺（deep blue），Are their color’s difference same as MnO₄^- 
and Mn²⁺？

In order to solve it , we started to do the reasrech. We tested different methods
much time to record . Finally , We found a good method . That’s placed a grating
in front of the digital camera len to take single slit diffraction spectrum pictures
in the dark space. Additionally we used spectrophotometer to measure the visible
light absorption spectrum. We compared and matched with single slit diffraction
spectrums and visible light absorption spectrums. Then we found the intense color
of MnO₄^-  due to charge transfer in reference book.




How about color’s difference between CrO₄^2- 、Cr₂O₇^2- 
、Cr³⁺group and  MnO₄、 Mn²⁺ group? We guess they had the same result .
We can find the λmax of CrO₄^2- 

、Cr₂O₇^2-  is larger than Cr³⁺  from the absorption
spectrum. But the observation from naked eyes was inverse . This is owing to our
vision is more sensitive to blue color. Refer Table 1.