Nucleation of Mixed Nitric Acid–Water Ice Nanoparticles in Molecular Beams that Starts with a HNO3 Molecule

0384182 - ÚFCH JH 2013 RIV US eng J - Journal Article
Lengyel, Jozef - Pysanenko, Andriy - Kočišek, Jaroslav - Poterya, Viktoriya - Pradzynski, Ch. C. - Zeuch, T. - Slavíček, Petr - Fárník, Michal
Nucleation of Mixed Nitric Acid–Water Ice Nanoparticles in Molecular Beams that Starts with a HNO3 Molecule.
Journal of Physical Chemistry Letters. Roč. 3, č. 21 (2012), s. 3096-3101. ISSN 1948-7185
R&D Projects: GA ČR GAP208/11/0161; GA ČR GA203/09/0422
Institutional support: RVO:61388955
Keywords : aerosol * polar stratospheric clouds * acidic dissociation
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 6.585, year: 2012

Mixed (HNO3)m(H2O)n clusters generated in supersonic expansion of nitric acid vapor are investigated in two different experiments, (1) time-of-flight mass spectrometry after electron ionization and (2) Na doping and photoionization. This combination of complementary methods reveals that only clusters containing at least one acid molecule are generated, that is, the acid molecule serves as the nucleation center in the expansion. The experiments also suggest that at least four water molecules are needed for HNO3 acidic dissociation. The clusters are undoubtedly generated, as proved by electron ionization; however, they are not detected by the Na doping due to a fast charge-transfer reaction between the Na atom and HNO3. This points to limitations of the Na doping recently advocated as a general method for atmospheric aerosol detection. On the other hand, the combination of the two methods introduces a tool for detecting molecules with sizable electron affinity in clusters.
Permanent Link: http://hdl.handle.net/11104/0213906