Lengyel Jozef, Ončák Milan, Fedor Juraj, Kočišek Jaroslav, Pysanenko Andriy, Beyer Martin K, Fárník Michal
J. Heyrovský Institute of Physical Chemistry v.v.i., Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic.
Phys Chem Chem Phys. 2017 May 17;19(19):11753-11758. doi: 10.1039/c7cp01205e.
Polar stratospheric clouds, which consist mainly of nitric acid containing ice particles, play a pivotal role in stratospheric chemistry. We investigate mixed nitric acid-water clusters (HNO)(HO), m ≈ 1-6, n ≈ 1-15, in a laboratory molecular beam experiment using electron attachment and mass spectrometry and interpret our experiments using DFT calculations. The reactions are triggered by the attachment of free electrons (0-14 eV) which leads to subsequent intracluster ion-molecule reactions. In these reactions, the nitrate anion NO turns out to play the central role. This contradicts the electron attachment to the gas-phase HNO molecule, which leads almost exclusively to NO. The nitrate containing clusters are formed through at least three different reaction pathways and represent terminal product ions in the reaction cascade initiated by the electron attachment. Besides, the complex reaction pathways represent a new hitherto unrecognized source of atmospherically important OH and HONO molecules.
极地平流层云主要由含冰颗粒的硝酸组成，在平流层化学中起着关键作用。我们在实验室分子束实验中，利用电子附着和质谱技术研究了混合硝酸 - 水团簇（HNO）（HO），其中m ≈ 1 - 6，n ≈ 1 - 15，并使用密度泛函理论计算来解释我们的实验。这些反应由自由电子（0 - 14电子伏特）的附着引发，进而导致团簇内后续的离子 - 分子反应。在这些反应中，硝酸根阴离子NO起着核心作用。这与电子附着到气相HNO分子的情况相矛盾，后者几乎只生成NO。含硝酸盐的团簇通过至少三种不同的反应途径形成，并且在由电子附着引发的反应级联中代表最终产物离子。此外，复杂的反应途径代表了一种迄今为止未被认识到的、对大气重要的OH和HONO分子的新来源。
