Chemical probes of metal cluster ionization potentials

Journal Article · Thu Mar 15 00:00:00 EST 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.457839· OSTI ID:6962981

Parks, E K; Klots, T D; Riley, S J ^[1]

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1. Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (US)

A procedure is described for the determination of metal cluster ionization potentials (IPs) using available excimer laser lines that gives error limits substantially smaller than traditional bracketing experiments. It is based on the observation that the adsorption of ammonia on cluster surfaces lowers cluster IPs, and that the IP lowering is linear in the number of adsorbed NH{sub 3} molecules. By determining the minimum number of NH{sub 3} molecules needed for ionization by the various excimer lasers, an approximation to the dependence of IP on coverage can be deduced. Extrapolation of this dependence to zero coverage gives the bare cluster IPs. Results are presented for clusters of iron, cobalt, and nickel having from 4 to 100 atoms. The effect of molecular adsorption on cluster IPs is analyzed theoretically, and the comparison with experimental results used to estimate the effective dipole moment of NH{sub 3} molecules adsorbed on these clusters. Comparison of the bare cluster IPs with the simple spherical drop model suggests that for transition metal clusters the Fermi level can be a significant function of cluster size.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6962981
• Journal Information: Journal of Chemical Physics; (USA), Vol. 92:6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AMMONIA
ADSORPTION
COBALT
IONIZATION POTENTIAL
SORPTIVE PROPERTIES
IRON
NICKEL
LASER RADIATION
PARTICULATES
SIZE
ELECTROMAGNETIC RADIATION
ELEMENTS
HYDRIDES
HYDROGEN COMPOUNDS
METALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
PARTICLES
RADIATIONS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties