Observation of H2 Aggregation onto a Doubly Charged Anion in a Temperature-Controlled Ion Trap

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 112; no. 51; pp. 13271 - 13274
• Main Authors: Wang, Xue-Bin, Xing, Xiao-Peng, Wang, Lai-Sheng
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 25.12.2008
• ISSN: 1089-5639; 1520-5215; 1520-5215
• DOI: 10.1021/jp808769m

Hydrogen is the second most difficult gas to be condensed due to its weak intermolecular interactions. Here we report observation of H2 aggregation onto a doubly charged anion, −O2C(CH2)12CO2 −(DC2−). Weakly bound DC2−(H2) n clusters were formed in a temperature-controlled ion trap and studied using photoelectron spectroscopy. The onset of clustering was observed at 30 K, whereas extensive condensation was observed at 12 K with n up to 12. Photoelectron spectra were obtained for DC2−(H2) n (n = 0−6) at 193 and 266 nm. The spectra of DC2−(H2) n were observed to be identical to that of the bare DC2− dianion except a slight blue shift, indicating the weak interactions between H2 and the parent dianion. The blue shift on average amounts to ∼34 meV (3.3 kJ/mol) per H2, which represents the lower limit of the H2 binding energy to DC2−.