Spectroscopic characterization of two peroxyl radicals during the O(2)-oxidation of the methylthio radical.
Spectroscopic characterization of two peroxyl radicals during the O(2)-oxidation of the methylthio radical.
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DOI：
10.1038/s42004-022-00637-z
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发表时间：
2022-02-17
影响因子：
5.9
通讯作者：
Zeng, Xiaoqing
中科院分区：
文献类型：
--
作者：
Wu, Zhuang;Shao, Xin;Zhu, Bifeng;Wang, Lina;Lu, Bo;Trabelsi, Tarek;Francisco, Joseph S.;Zeng, Xiaoqing
二甲基硫醚（DMS）的大气氧化产生硫酸和甲磺酸（MSA），它们是通过均质成核和在空气团中进一步簇生长形成新颗粒的关键前体。实验和理论研究表明，DMS的氧化反应首先生成甲硫基自由基（CH 3S·），然后通过自由基CH 3SOx·（x = 1-4）的介导进行O2-氧化反应。因此，捕获这些瞬态自由基并揭示它们的反应性对于理解复杂的机制至关重要。在CCSD（T）/aug-cc-pV（X + d）Z（X = D和T）理论水平上，结合基质隔离光谱（IR和UV-vis）和量子化学计算，研究了CH 3S·的O2氧化反应.过氧自由基CH 3SOO·是CH 3S·初始氧化的关键中间体，与O2反应生成。在830 nm的光照射下，CH 3SO·在低温基质（Ar、Ne和N2）中发生异构化反应生成磺酰基自由基CH 3SO 2·，后者在440 nm的光照射下进一步与O2联合收割机结合生成另一个过氧自由基CH 3S（O）2 OO·。随后的紫外光照射（266 nm）导致CH 3S（O）2 OO·分解为CH 3SO 2·、CH 2 O、SO2和SO 3。18 O-和13 C-同位素标记实验也支持了两个过氧自由基CH_3SO·和CH_3S（O）_2 OO·的红外光谱鉴定。二甲基硫醚的大气氧化影响地球的气候，但这种复杂反应的复杂途径仍然没有得到充分的描述。在这里，作者使用一个优化的闪速热解方法气相生成的甲硫基自由基研究其O2-氧化通过基质隔离光谱，并明确确定两个过氧自由基中间体。
The atmospheric oxidation of dimethyl sulfide (DMS) yields sulfuric acid and methane sulfonic acid (MSA), which are key precursors to new particles formed via homogeneous nucleation and further cluster growth in air masses. Comprehensive experimental and theoretical studies have suggested that the oxidation of DMS involves the formation of the methylthio radical (CH3S•), followed by its O2-oxidation reaction via the intermediacy of free radicals CH3SOx• (x = 1–4). Therefore, capturing these transient radicals and disclosing their reactivity are of vital importance in understanding the complex mechanism. Here, we report an optimized method for efficient gas-phase generation of CH3S• through flash pyrolysis of S-nitrosothiol CH3SNO, enabling us to study the O2-oxidation of CH3S• by combining matrix-isolation spectroscopy (IR and UV–vis) with quantum chemical computations at the CCSD(T)/aug-cc-pV(X + d)Z (X = D and T) level of theory. As the key intermediate for the initial oxidation of CH3S•, the peroxyl radical CH3SOO• forms by reacting with O2. Upon irradiation at 830 nm, CH3SOO• undergoes isomerization to the sulfonyl radical CH3SO2• in cryogenic matrixes (Ar, Ne, and N2), and the latter can further combine with O2 to yield another peroxyl radical CH3S(O)2OO• upon further irradiation at 440 nm. Subsequent UV-light irradiation (266 nm) causes dissociation of CH3S(O)2OO• to CH3SO2•, CH2O, SO2, and SO3. The IR spectroscopic identification of the two peroxyl radicals CH3SOO• and CH3S(O)2OO• is also supported by 18O- and 13C-isotope labeling experiments. The atmospheric oxidation of dimethyl sulfide affects the Earth’s climate, but the intricate pathways of this complex reaction are still not fully described. Here, the authors use an optimized flash pyrolysis method for gas-phase generation of the methylthio radical to study its O2-oxidation via matrix-isolation spectroscopy, and unambiguously identify two peroxyl radical intermediates.
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影响因子：
5.2
作者：
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通讯作者：
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影响因子：
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影响因子：
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作者：
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影响因子：
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作者：
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影响因子：
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