3月21日的《科學(xué)》（Science）雜志報道說,，新的實驗顯示，帶有電子負(fù)荷的二氧化氮與水的反應(yīng)是地球較低大氣層中羥基基團(tuán)（OH）的一個關(guān)鍵性的來源,。正如Shuping Li及其同事所發(fā)現(xiàn)的,，即使在相對較低濃度的情況下，羥基基團(tuán)仍然是大氣中的重要成分,，因為它們充當(dāng)?shù)氖?ldquo;凈化劑”的角色,，即它們控制著大氣清除污染物的能力。到現(xiàn)在為止,，對流層OH被認(rèn)為主要是由于日光將位于大氣層中的臭氧分子進(jìn)行分解之后產(chǎn)生的,。但是Li及其同事經(jīng)過計算后發(fā)現(xiàn)，在某些情形下,，處于激發(fā)態(tài)的二氧化氮和水的反應(yīng)可以產(chǎn)生多達(dá)50%的大氣層較低部位的OH,。正如Paul Wennberg 及 Donald Dabdub在一則相關(guān)的Perspective中所討論的，這一發(fā)現(xiàn)對城市空氣質(zhì)量模型的制作可能有意義,，因為OH與二氧化氮基團(tuán)之間的反應(yīng)對決定臭氧產(chǎn)生的速率是很重要的,。（來源：EurekAlert!中文版）
生物谷推薦原始出處：
（Science），Vol. 319. no. 5870, pp. 1657 - 1660,，Shuping Li,，Amitabha Sinha
Atmospheric Hydroxyl Radical Production from Electronically Excited NO2 and H2O
Shuping Li, Jamie Matthews, Amitabha Sinha*
Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(1D) + H2O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation.
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0314, USA.
