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MICHAEL asked in 科學其他:科學 · 1 decade ago

儀器分析,請舉一些 IR active及inactive物質

請『簡單』介紹物質為何會有 IR active 及 IR inactive 的特性

(請稍微解釋一下謂何有些dipole物質能被infrared spectrum吸收)

主要的問題為:

請舉出一些 IR active 及 IR inactive 的物質

不用太多,一些常見的物質就好,

例如 CO (C=O)為 IR active;CO2 (O=C=O)為 IR inactive 等等

1 Answer

Rating
  • ?
    Lv 7
    1 decade ago
    Favorite Answer

    iR active或inactive關鍵在分子鍵的振動是否產生偶極矩的變化.這跟分子的對稱性很有關係.

    一個有i對稱的分子沒有永久的偶極矩,它對於i對稱的振動不會產生偶極矩的變化,所以是iR inactive,但是如果振動不是i對稱,則有偶極矩的變化,是iR active.

    例: CO2的對稱伸張(1340 cm-1)是iR inactive,不對稱伸張(2349 cm-1)是iR active. 丙炔的C=C對稱伸張(2150 cm-1)是iR active. 二丁炔的C=C對稱伸張(2150 cm-1)是iR inactive. 1,2-二氯乙烯中C=C和C-Cl的對稱擺動(1580和840 cm-1)是iR inactive, C-Cl的不對稱擺動(895 cm-1)是iR active.

    希望這個解說對你有幫助.

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