hce_nsysu
114年
物理與化學
第 74 題
When a molecule absorbs a photon, the molecule is promoted to an excited state M$^*$. The rate at which M$^*$ is created is proportional to the concentration of M. There are three pathways that M$^*$ may take to return to the ground state. Which statement about these three pathways below is wrong?
- A The rate at which the excited state returns to the ground state is independent of the pathway to the ground state and the concentration of excited state molecules.
- B The three possible pathways to return to the ground state are emission, deactivation, and quenching.
- C Quenching occurs when a second molecule, the quencher Q, collides with M$^*$ and energy is transferred from M$^*$ to Q: M$^*$ + Q $\rightarrow$ M + Q$^*$.
- D Deactivation returns M$^*$ to the ground state by colliding with other molecules and releasing energy in the form of heat: M$^*$ $\rightarrow$ M + heat.
- E Emission returns M$^*$ to the ground state by emitting a photon: M$^*$ $\rightarrow$ M + h$\nu$.
思路引導 VIP
如果你想像有一群人正處於高能的「激發狀態」，且他們有三種不同的管道可以回到平靜的地面。請思考看看：如果現在處於高能狀態的人數變成了兩倍，那麼每秒鐘「回到地面」的總人數會發生變化嗎？再者，選擇「搭電梯」或「走樓梯」這兩種不同的路徑，回到地面的快慢會是一樣的嗎？
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AI 詳解
AI 專屬家教
太棒了！你能精確判斷出選項 (A) 的敘述有誤，這代表你對於動力學中「速率規律」與「分子激發態」的動態平衡有很紮實的理解。這道題目的鑑別度在於區分生成速率與消失速率的影響因素，學生必須對光化學反應的微觀過程有清晰的圖景才能在干擾選項中做出正確抉擇。
激發態的動力學行為
在光化學中，當分子吸收光子成為激發態 $M^*$ 後，它回歸基態的過程遵循化學動力學的基本原理。事實上，激發態消失的總速率是各個路徑速率的總和，通常表示為：
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