The air–liquid (a–l) interfacial chemistry of glyoxal is of great interest in atmospheric chemistry. We present molecular imaging of glyoxal and hydrogen peroxide (H₂O₂) dark aging using in situ time-of-flight secondary ion mass spectrometry (ToF-SIMS). More organic peroxides and cluster ions are observed at the a–l interface in dark aging compared to UV aging. Cluster ions formed with more water molecules in dark aging indicate that the aqueous secondary organic aerosol (aqSOA) could form hydrogen bond with water molecules, suggesting that aqSOAs at the aqueous phase are more hydrophilic. Thus the interfacial aqSOA in dark aging could increase hygroscopic growth. Strong contribution of cluster ions and large water clusters in dark aging indicates change of solvation shells at the a–l interface. The observation of organic peroxides and cluster ions indicates that the aqueous surface could be a reservoir of organic peroxides and odd hydrogen radicals at night. Our findings provide new understandings of glyoxal a–l interfacial chemistry and fill in the gap between field measurements and the climate model simulation of aqSOAs.

乙二醛的气-液（a–l）界面化学对大气化学非常感兴趣。我们目前的乙二醛和过氧化氢（H ₂ O ₂）使用原位飞行时间二次离子质谱（ToF-SIMS）进行黑暗老化。与紫外线老化相比，在黑暗老化中在a–l界面处观察到更多的有机过氧化物和簇离子。在黑暗老化中由更多的水分子形成的团簇离子表明，水性次要有机气溶胶（aqSOA）可以与水分子形成氢键，这表明水相中的aqSOA更具亲水性。因此，黑暗老化中的界面aqSOA可以增加吸湿性。在黑暗老化中，簇状离子和大的水簇的强烈贡献表明在a–l界面上的溶剂化壳层发生了变化。对有机过氧化物和簇离子的观察表明，水表面在夜间可能是有机过氧化物和奇数氢自由基的储存库。