利用雷射光解-共振螢光法測量氯原子與 HCFC-141b(CH3CFCl2)於室溫下(298K)之反應速率係數值

Abstract

本研究利用雷射光解-共振螢光法測量氯原子與CH3CFCl2 (HCFC-141b)於室溫下(298K)之反應速率係數值。 Cl + CH3CFCl2 → HCl + CH2CFCl2 吾人嘗試使用下列兩種方法來產生氯原子: (1)CCl4 + hν(l93 nm) → Cl(2P) + CCl3 (1-19) CCl4 + hν(l93 nm) → 2Cl(2P) + CCl2 (1-20) (2)Cl2 + hν(355 nm) → 2Cl(2P3/2) (1-21) 結果顯示以光解Cl2製造Cl較適用於此動力學之研究。在反應壓力為45torr時得到反應(1-19)之kⅡ= (5.12─6.07) ╳lO-14 cm3 molecule-1 s-1。我們發現光解雷射能量 (1.1─18.6 mJ/cm2)對實驗結果並不會影響。 當[Cl]增至1╳1013 molecule cm-3， Cl則有再生現象。

The absolute rate coefficient for the reaction of Cl atoms with CH3CFCl2 (HCFC-l41b) has been determined using laser photolysis-resonance fluorescence technique at 298 K and 45 torr. Cl + CH3CFCl2 → HCl + CH2CFCl2 (1-19) Two Cl radicals source reactions were tested, (1)CCl4 + hν(l93 nm) → Cl(2P) + CCl3 CCl4 + hν(l93 nm) → 2Cl(2P) + CCl2 (1-20) (2)Cl2 + hν(355 nm) → 2Cl(2P3/2) (1-21) Cl2 was found to be a better precursor for the rate coefficient measurements. We obtained a second-order rate coefficient : kⅡ=(5.12─6.07) ╳lO-14 cm3 molecule-1 s-1.The energy of photolysis laser (1.1─18.6 mJ/cm2) did not affect the measured rate coefficient. When [Cl] was higher than 1 ╳1013 molecule cm-3, Cl regenerations were observed .