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asked in 科學化學 · 1 decade ago

何謂紅外線活潑 (infrared active)

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請問何謂紅外線活潑 (infrared active)?

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  • 1 decade ago
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    1.就是物質(分子)的化學鍵的振動(vibration)能量與紅外線的某個或某段頻率(或波長)相同而產生共振吸收

    To be "active" means that absorption of a photon to excite the vibration is allowed by the rules of quantum mechanics.

    [Aside: the infrared "selection rule" states that for a particular vibrational mode to be observed (active) in the infrared spectrum, the mode must involve a change in the dipole moment of the molecule.]

    但量子力學在紅外光譜的共振吸收的選擇律("selection rule")

    是分子的振動必須要有極性變化

    2.例如: 二氧化碳的兩個C=O共價鍵的振動模式有四種:

    其中A是 IR inactive

    B ,C,D都是IR active

    B的吸收在2349

    圖片參考:http://www.wag.caltech.edu/home/jang/genchem/img21...

    (4.26 um)

    C和D的吸收在667

    圖片參考:http://www.wag.caltech.edu/home/jang/genchem/img21...

    (15.00 um)

    圖片參考:http://www.wag.caltech.edu/home/jang/genchem/ir_im...

    The asymmetric stretch (B) is infrared active because there is a change in the molecular dipole moment during this vibration.

    參考網頁:

    http://www.wag.caltech.edu/home/jang/genchem/infra...

    2007-11-06 22:44:25 補充:

    IR active可譯為"具有紅外線吸收的活性"

    IR inactive可譯為"不具有紅外線吸收的活性"

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