【摘要】：本文采用195.8 nm飛秒激光將丁酮分子激發(fā)到S_2(n,3s)里德堡態(tài),在800 nm探測光的作用下獲得時(shí)間分辨的飛行時(shí)間質(zhì)譜.對實(shí)驗(yàn)結(jié)果的分析表明,由于丁酮α位置具有一個(gè)甲基和一個(gè)乙基,使得NorrishⅠ型解離反應(yīng)表現(xiàn)出豐富的動(dòng)力學(xué)特征.母體離子瞬態(tài)衰減的時(shí)間常數(shù)為(2.23±0.02)ps.丙酰基離子瞬態(tài)衰減與母體類似,只有一個(gè)為(2.15±0.02)ps的時(shí)間常數(shù),說明丙�；x子來自于母體的解離性電離.乙�；x子的時(shí)間曲線擬合得到四個(gè)時(shí)間常數(shù):τ_1=(2.40±0.15)ps,τ_2=(1.10±0.25)ps,τ_3=(0.08±0.02)ps,τ_4=(17.72±0.80)ps,分別對應(yīng)于S_2→S_1的內(nèi)轉(zhuǎn)換,S_1態(tài)生成CH_3CO(A)的初步解離,CH_3CO(A)快速內(nèi)轉(zhuǎn)換為CH_3CO(X),以及CH_3CO(X)基態(tài)上的二次解離.丁酮分子α-C-C鍵的解離存在分子內(nèi)振動(dòng)能量再分配(IVR)與勢壘解離兩種競爭的解離通道,但在該實(shí)驗(yàn)條件下,我們認(rèn)為是通過分子內(nèi)振動(dòng)能量再分配通道發(fā)生解離的結(jié)果.
[Abstract]:In this paper, a 195.8 nm femtosecond laser is used to excite the butanone molecule to the S _ S _ 2 (n ~ 3s) Rydberg state. The time-resolved time-of-flight mass spectrometry is obtained under the action of 800nm probe light. The analysis of the experimental results shows that the dissociation reaction of Norrish type I exhibits rich kinetic characteristics due to the presence of one methyl and one ethyl in the 偽 position of butanone. The time constant of the transient decay of the parent ion is (2.23 鹵0.02) PS. The transient decay of propionyl ions is similar to that of the parent, with only one time constant of (2.15 鹵0.02) PS, which indicates that the propionyl ion comes from the dissociation ionization of the parent. Four time constants were obtained by fitting the time curve of acetyl ions: 蟿 _ 1 = (2.40 鹵0.15) pss, 蟿 _ s _ 2 = (1.10 鹵0.25) pss, 蟿 _ 3 = (0.08 鹵0.02) pss, 蟿 _ 4 = (17.72 鹵0.80) pss, respectively, corresponding to the initial dissociation of S _ 2 / S _ 2 / S _ (1) and the initial dissociation of Ch _ 3CO (A) to CH_3CO (X), and the second dissociation of CH_3CO (X) in ground state. The dissociation of the 偽 -C-C bond of butanone molecule has two competitive dissociation channels: intramolecular vibrational energy redistribution (IVR) and barrier dissociation. However, under these experimental conditions, we believe that the dissociation results occur through the intramolecular vibrational energy redistribution channel.
【作者單位】： 昆明學(xué)院物理科學(xué)與技術(shù)系;中國科學(xué)院武漢物理與數(shù)學(xué)研究所波譜與原子分子物理國家重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃(批準(zhǔn)號:2013CB922200) 國家自然科學(xué)基金(批準(zhǔn)號:21573279,21273274)資助的課題~~
【分類號】：O623.521
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本文編號：2142939