Hydrogen bonding on iron: Correlation of adsorption and desorption states on Fe(100) and perturbation of the Fe-H bond with coadsorbed CO

SURFACE SCIENCE

卷:347

Article

Merrill, PB ; Madix, RJ

关键词: adsorption kinetics;    carbon monoxide;    catalysis;    chemisorption;    electron energy loss spectroscopy;    hydrogen;    iron;    low index single crystal surfaces;    molecule-solid reactions;    thermal desorption;    thermal desorption spectroscopy;    vibrations of adsorbed molecules;   

DOI  :  10.1016/0039-6028(95)01016-5

来源: Elsevier

【 摘 要 】

Electron energy loss vibrational spectra suggest that hydrogen first adsorbs on Fe(100) in four-fold hollows (beta(2)) and converts to sites of lower ligancy (beta(1)) with increasing coverage. The beta(1) state desorbs with pseudo first-order kinetics with an activation energy of 14.1 kcal/mol. The beta(2) state exhibits a vibrational frequency of 700 cm(-1), indicative of adsorption in four-fold hollows. With increasing coverage this mode is replaced by a vibration at 1000 cm(-1), indicative of conversion of adsorbed H to an asymmetric position within the four-fold hollow. Adsorption of CO onto the H-covered surface causes an increase in the frequency of the mode near 1000 cm(-1) associated with movement to a position of lower ligancy within the four-fold hollow.

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