Features and mechanism of H- anion emission from 12 CaO x 7 Al2O3 surface.
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).
Huang
Fan
F
Department of Chemical Physics, Lab of Biomass Clean Energy, University of Science & Technology of China, Hefei, Anhui, 230026, PR China.
Li
Jiang
J
Wang
Lian
L
Dong
Ting
T
Tu
Jing
J
Torimoto
Yoshifumi
Y
Sadakata
Masayoshi
M
Li
Quanxin
Q
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
D000838:Anions; D017610:Calcium Compounds; D010087:Oxides; D011522:Protons; C016538:lime; D000537:Aluminum Oxide