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Formation of even-numbered hydrogen cluster cations in ultracold helium droplets.
Formation of even-numbered hydrogen cluster cations in ultracold helium droplets.
- Source :
- Journal of Chemical Physics; 12/14/2008, Vol. 129 Issue 22, p224306, 8p, 1 Diagram, 1 Chart, 5 Graphs
- Publication Year :
- 2008
-
Abstract
- Neutral hydrogen clusters are grown in ultracold helium nanodroplets by successive pickup of hydrogen molecules. Even-numbered hydrogen cluster cations are observed upon electron-impact ionization with and without attached helium atoms and in addition to the familiar odd-numbered H<subscript>n</subscript><superscript>+</superscript>. The helium matrix affects the fragmentation dynamics that usually lead to the formation of overwhelmingly odd-numbered H<subscript>n</subscript><superscript>+</superscript>. The use of high-resolution mass spectrometry allows the unambiguous identification of even-numbered H<subscript>n</subscript><superscript>+</superscript> up to n≅120 by their mass excess that distinguishes them from He<subscript>n</subscript><superscript>+</superscript>, mixed He<subscript>m</subscript>H<subscript>n</subscript><superscript>+</superscript>, and background ions. The large range in size of these hydrogen cluster ions is unprecedented, as is the accuracy of their definition. Apart from the previously observed magic number n=6, pronounced drops in the abundance of even-numbered cluster ions are seen at n=30 and 114, which suggest icosahedral shell closures at H<subscript>6</subscript><superscript>+</superscript>(H<subscript>2</subscript>)<subscript>12</subscript> and H<subscript>6</subscript><superscript>+</superscript>(H<subscript>2</subscript>)<subscript>54</subscript>. Possible isomers of H<subscript>6</subscript><superscript>+</superscript> are identified at the quadratic configuration interaction with inclusion of single and double excitations (QCISD)/aug-cc-pVTZ level of theory [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00219606
- Volume :
- 129
- Issue :
- 22
- Database :
- Complementary Index
- Journal :
- Journal of Chemical Physics
- Publication Type :
- Academic Journal
- Accession number :
- 35763955
- Full Text :
- https://doi.org/10.1063/1.3035833