Effect of Sm valence changes on photoemission spectra

Journal Article · Fri Apr 15 04:00:00 EDT 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.6605· OSTI ID:5452160

denBoer, M L; Chang, C L; Horn, S; Murgai, V

We have used low-energy (h..nu.. = 17--45 eV) photoemission to study thin films of Sm evaporated on Nb. We find that Sm evaporated onto a room-temperature Nb substrate is initially entirely divalent. On a time scale of the order of 50 min at room temperature a valence transition to mixed-valent or trivalent Sm occurs. This is accompanied by dramatic changes in the photoemission spectra, including a large increase in the total yield of photoelectrons and the appearance of a series of new constant-kinetic-energy peaks. The photon-energy dependence of these peaks indicates that they are due to Auger recombination of the Sm 5p level. We also observe a 5p..-->..5d resonance in Sm for the first time. The underlying cause of these effects appears to be an ordering transition in the Sm film, which changes the Sm 5d occupancy and increases the resonance amplitude. This mechanism is evidently a very sensitive indicator of a Sm valence change.

• Research Organization: Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10021
• OSTI ID: 5452160
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 37:12; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
BREMSSTRAHLUNG
CORRELATIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION
ENERGY SPECTRA
FILMS
METALS
NIOBIUM
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
PHOTOEMISSION
RADIATIONS
RARE EARTHS
SAMARIUM
SECONDARY EMISSION
SPECTRA
SUBSTRATES
SYNCHROTRON RADIATION
THIN FILMS
TRANSITION ELEMENTS
VALENCE