title: Excitons at the B K edge of boron nitride nanotubes probed by x-ray absorption spectroscopy.
abstract: We have performed a near-edge x-ray absorption fine-structure (NEXAFS) investigation of multi-walled boron nitride nanotubes (BNNTs). We show that the one-dimensionality of BNNTs is clearly evident in the B K edge spectrum, while the N K edge spectrum is similar to that of layered hexagonal BN (h-BN). We observe a sharp feature at the σ* onset of the B K edge, which we ascribe to a core exciton state. We also report a comparison with spectra taken after an ammonia plasma treatment, showing that the B K edge becomes indistinguishable from that of h-BN, due to the breaking of the tubular order and the formation of small h-BN clusters.
authors.affiliation: Istituto Nazionale di Fisica Nucleare (INFN) and Dipartimento di Fisica Università della Calabria, Cosenza, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Pacilé
authors.forename: M
authors.initials: M
authors.lastname: Papagno
authors.forename: T
authors.initials: T
authors.lastname: Skála
authors.forename: V
authors.initials: V
authors.lastname: Matolín
authors.forename: T
authors.initials: T
authors.lastname: Sainsbury
authors.forename: T
authors.initials: T
authors.lastname: Ikuno
authors.forename: D
authors.initials: D
authors.lastname: Okawa
authors.forename: A
authors.initials: A
authors.lastname: Zettl
authors.forename: K C
authors.initials: KC
authors.lastname: Prince