Photoionization studies of niobium clusters: Ionization potentials for Nb sub 2 --Nb sub 76

Journal Article · Mon Oct 15 00:00:00 EDT 1990 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.459570· OSTI ID:6412236

Knickelbein, M B; Yang, S ^[1]

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

The photoionization efficiency (PIE) spectra for niobium clusters up to Nb{sub 76} are measured using laser ionization time-of-flight mass spectrometry. Ionization potentials (IPs) assigned from the PIE spectra evolve with the same general pattern observed for other transition metal clusters ({ital M}{sub {ital n}}) studied to date: a rapid yet nonmonotonic decrease in IP to {ital n}{approx equal}15 followed thereafter by a relatively slow and smooth evolution. The measured IPs evolve with cluster radius {ital R} according to the predictions of the conducting spherical droplet model if the limiting ({ital R}{r arrow}{infinity}) IP is chosen to be 0.5 eV lower than the bulk polycrystalline work function. Kinetics experiments using D{sub 2} as the coreactant indicate the existence of two structural forms, one highly reactive, one relatively unreactive for clusters in the size range Nb{sub 9}--Nb{sub 12}, with the reactive forms predominant in each case. PIE spectra for Nb{sub 9}--Nb{sub 12} were recorded using sufficient D{sub 2} added to the cluster source to selectively titrate the reactive forms of these clusters, leaving the unreactive forms as the predominant isomers. It is found that the unreactive forms of Nb{sub 9} and Nb{sub 12} possess higher IPs than those of the reactive forms, while both forms of Nb{sub 10} possess approximately the same IP.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6412236
• Journal Information: Journal of Chemical Physics; (USA), Vol. 93:8; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
NIOBIUM
PHOTOIONIZATION
SOLID CLUSTERS
IONIZATION POTENTIAL
CHEMICAL REACTIONS
DEUTERIUM
ISOMERIZATION
LASER RADIATION
TIME-OF-FLIGHT MASS SPECTROMETERS
WORK FUNCTIONS
DYNAMIC MASS SPECTROMETERS
ELECTROMAGNETIC RADIATION
ELEMENTS
FUNCTIONS
HYDROGEN ISOTOPES
IONIZATION
ISOTOPES
LIGHT NUCLEI
MASS SPECTROMETERS
MEASURING INSTRUMENTS
METALS
NUCLEI
ODD-ODD NUCLEI
RADIATIONS
SPECTROMETERS
STABLE ISOTOPES
TIME-OF-FLIGHT SPECTROMETERS
TRANSITION ELEMENTS
360104* - Metals & Alloys- Physical Properties
360102 - Metals & Alloys- Structure & Phase Studies