title: Features and mechanism of H- anion emission from 12 CaO x 7 Al2O3 surface.
abstract: The hydrogen anion (H-) and other anionic species (O-, OH-, e-) in the gas phase, emitted from the synthesized crystal surface of 12 CaO x 7 Al2O3-H- (C12A7-H-), have been observed. The emission intensity of all the anionic species strongly depends on the sample surface temperature and the extraction field. H- has the highest emission branch ratio, and the extraction field can reduce its apparent activation energy. H- emission current at a microA/cm2-level has been achieved, which is about 4 orders of magnitude higher than that obtained from the thermal desorption process of CaH2. The observed anions of H- and OH- are attributed to their migration from the C12A7-H- cages onto the surface [i.e., Y-(cages) --> Y-(surface) --> Y-(gas phase) (Y = H, OH)]. The weak O- and electron emission would both arise from the dissociation of O2-: O2-(surface) --> O-(surface) + e-(surface) --> O-(gas phase) + e-(space).
authors.affiliation: Department of Chemical Physics, Lab of Biomass Clean Energy, University of Science & Technology of China, Hefei, Anhui, 230026, PR China.
authors.forename: Fan
authors.initials: F
authors.lastname: Huang
authors.forename: Jiang
authors.initials: J
authors.lastname: Li
authors.forename: Lian
authors.initials: L
authors.lastname: Wang
authors.forename: Ting
authors.initials: T
authors.lastname: Dong
authors.forename: Jing
authors.initials: J
authors.lastname: Tu
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Torimoto
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Sadakata
authors.forename: Quanxin
authors.initials: Q
authors.lastname: Li
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D000838:Anions / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D004583:Electrons; D013058:Mass Spectrometry; D010087:Oxides / Q000737:chemistry*; D011522:Protons; D013499:Surface Properties; D013696:Temperature
chemical_list: D000838:Anions; D017610:Calcium Compounds; D010087:Oxides; D011522:Protons; C016538:lime; D000537:Aluminum Oxide