Lu Bo, Trabelsi Tarek, Esposito Vincent J, Fortenberry Ryan C, Francisco Joseph S, Zeng Xiaoqing
Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysts and Innovative Materials, Fudan University, Shanghai, 200433, China.
Department of Earth and Environmental Science and Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
J Phys Chem A. 2021 Dec 23;125(50):10615-10621. doi: 10.1021/acs.jpca.1c09311. Epub 2021 Dec 10.
Sulfur-containing radicals HSO and HOSO are key intermediates involved in stratospheric sulfur geoengineering by SO injection. The spectroscopic characterization and photochemistry of both radicals are crucial to understanding the chemical impact of SO chemistry in the stratosphere. On the basis of the efficient generation of HOSO by flash pyrolysis of gaseous sulfinic acid, CHFS(O)OH, a strong absorption is observed at 270 nm along with a shoulder up to 350 nm for HOSO isolated in low-temperature noble gas matrixes (Ar and Ne). These mainly arise from the excitations from the ground state (XA) to the CA/DA and AA/BA states, respectively. Upon a 266 nm laser irradiation, the broad absorption band in the range 320-500 nm for HSO appears, and it corresponds to the combination of three excitations from the XA state to the first (AA), second (BA), and third (CA) excited states. Assignment of the UV-vis spectra is consistent with the photochemistry of HOSO and HSO as observed by matrix-isolation IR spectroscopy and also by the agreement with high-level calculations.
含硫自由基HSO和HOSO是通过注入SO₂进行平流层硫地球工程的关键中间体。这两种自由基的光谱表征和光化学对于理解平流层中SO₂化学的化学影响至关重要。基于气态亚磺酸CHF₂S(O)OH的快速热解高效生成HOSO，在低温稀有气体基质（Ar和Ne）中分离出的HOSO在270 nm处观察到强烈吸收，同时在350 nm处有一个肩峰。这些主要分别来自基态（XA）到CA/DA和AA/BA态的激发。在266 nm激光照射下，HSO在320 - 500 nm范围内出现宽吸收带，它对应于从XA态到第一（AA）、第二（BA）和第三（CA）激发态的三种激发的组合。紫外可见光谱的归属与基质隔离红外光谱观察到的HOSO和HSO的光化学一致，也与高水平计算结果相符。
