title: Size-dependent vibronic coupling in α-Fe2O3.
abstract: We report the discovery of finite length scale effects on vibronic coupling in nanoscale α-Fe2O3 as measured by the behavior of vibronically activated d-d on-site excitations of Fe(3+) as a function of size and shape. An oscillator strength analysis reveals that the frequency of the coupled symmetry-breaking phonon changes with size, a crossover that we analyze in terms of increasing three-dimensional character to the displacement pattern. These findings demonstrate the flexibility of mixing processes in confined systems and suggest a strategy for both enhancing and controlling charge-lattice interactions in other materials.
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: K R
authors.initials: KR
authors.lastname: O'Neal
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Patete
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: P
authors.initials: P
authors.lastname: Chen
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Holinsworth
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Smith
authors.affiliation: Department of Physics and IPAP, Yonsei University, Seoul 120-749, South Korea.
authors.forename: N
authors.initials: N
authors.lastname: Lee
authors.affiliation: Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: S-W
authors.initials: SW
authors.lastname: Cheong
authors.affiliation: Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, USA.
authors.forename: Stanislaus S
authors.initials: SS
authors.lastname: Wong
authors.affiliation: Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA.
authors.forename: C
authors.initials: C
authors.lastname: Marques
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Aronson
authors.affiliation: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Musfeldt