title: Low-frequency Raman scattering of bioinspired self-assembled diphenylalanine nanotubes/microtubes.
abstract: Low-frequency Raman scattering from self-assembled bioinspired diphenylalanine (FF) nanotubes/microtubes (NTs/MTs) has been observed for the first time. Four double peaks are identified as the three-dimensional localized collective (acoustic phonon) vibrations of FF molecules in the subnanometer crystalline structure (biological building block) forming the FF NTs/MTs. The increased energy separations between two subpeaks caused by the loss of water in the nanochannel cores are due to the enhancement of vibrational couplings between the FF molecules as a result of the reduction of the influence from water on the coupling. The results provide experimental evidence of localized but still weakly coupled vibrations in organic crystalline nanostructures in the low-frequency region.
authors.affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China. hkxlwu@nju.edu.cn
authors.forename: Xinglong
authors.initials: X
authors.lastname: Wu
authors.forename: Shijie
authors.initials: S
authors.lastname: Xiong
authors.forename: Minjie
authors.initials: M
authors.lastname: Wang
authors.forename: Jiancang
authors.initials: J
authors.lastname: Shen
authors.forename: Paul K
authors.initials: PK
authors.lastname: Chu
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D004151:Dipeptides; D008027:Light; D008422:Materials Testing; D008870:Microtubules / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D012542:Scattering, Radiation; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D004151:Dipeptides; C026650:phenylalanylphenylalanine; D010649:Phenylalanine