Cluster cross sections from pickup measurements: Are the established methods consistent?

0371733 - ÚFCH JH 2012 RIV US eng J - Článek v odborném periodiku
Fedor, J. - Poterya, Viktoriya - Pysanenko, Andriy - Fárník, Michal
Cluster cross sections from pickup measurements: Are the established methods consistent?
Journal of Chemical Physics. Roč. 135, č. 10 (2011), s. 104305. ISSN 0021-9606. E-ISSN 1089-7690
Grant CEP: GA ČR GA203/09/0422; GA ČR GAP208/11/0161; GA AV ČR KJB400400902
Výzkumný záměr: CEZ:AV0Z40400503
Klíčová slova: liquid-helium clusters * water clusters * molecular-beam
Kód oboru RIV: CF - Fyzikální chemie a teoretická chemie
Impakt faktor: 3.333, rok: 2011

Pickup of several molecules, H(2)O, HBr, and CH(3)OH, and Ar atoms on free Ar(N) clusters has been investigated in a molecular beam experiment. The pickup cross sections of the clusters with known mean sizes, (N) over bar approximate to 150 and 260 were measured by two independent methods: (i) the cluster beam velocity decrease due to the momentum transfer of the picked up molecules to the clusters, and (ii) Poisson distribution of a selected cluster fragment ion as a function of the pickup pressure. In addition, the pickup cross sections were calculated using molecular dynamics and Monte Carlo simulations. The simulations support the results of the velocity measurements. On the other hand, the Poisson distributions yield significantly smaller cross sections, inconsistent with the known Ar(N) cluster sizes. These results are discussed in terms of: (i) an incomplete coagulation of guest molecules on the argon clusters when two or more molecules are picked up; and (ii) the fragmentation pattern of the embedded molecules and their clusters upon ionization on the Ar cluster.
Trvalý link: http://hdl.handle.net/11104/0205181