title: Inelastic x-ray scattering study of exciton properties in an organic molecular crystal.
abstract: Excitons in a complex organic molecular crystal were studied by inelastic x-ray scattering (IXS) for the first time. The dynamic dielectric response function is measured over a large momentum transfer region, from which an exciton dispersion of 130 meV is observed. Semiempirical quantum chemical calculations reproduce well the momentum dependence of the measured dynamic dielectric responses, and thus unambiguously indicate that the lowest Frenkel exciton is confined within a fraction of the complex molecule. Our results demonstrate that IXS is a powerful tool for studying excitons in complex organic molecular systems. Besides the energy position, the IXS spectra provide a stringent test on the validity of the theoretically calculated exciton wave functions.
authors.affiliation: Department of Physics, and Applied Surface Physics State Key Laboratory, Fudan University, Shanghai 200433, China.
authors.forename: K
authors.initials: K
authors.lastname: Yang
authors.forename: L P
authors.initials: LP
authors.lastname: Chen
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Cai
authors.forename: N
authors.initials: N
authors.lastname: Hiraoka
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.forename: J F
authors.initials: JF
authors.lastname: Zhao
authors.forename: D W
authors.initials: DW
authors.lastname: Shen
authors.forename: H F
authors.initials: HF
authors.lastname: Song
authors.forename: H
authors.initials: H
authors.lastname: Tian
authors.forename: L H
authors.initials: LH
authors.lastname: Bai
authors.forename: Z H
authors.initials: ZH
authors.lastname: Chen
authors.forename: Z G
authors.initials: ZG
authors.lastname: Shuai
authors.forename: D L
authors.initials: DL
authors.lastname: Feng
mesh_terms: D003460:Crystallization; D008958:Models, Molecular; D010078:Oxazines / Q000737:chemistry*; D012542:Scattering, Radiation; D013057:Spectrum Analysis / Q000379:methods*; D013141:Spiro Compounds / Q000737:chemistry*; D014965:X-Rays
chemical_list: D010078:Oxazines; D013141:Spiro Compounds