title: Application of time- and space-resolved fluorescence spectroscopy to the distribution of guest species into micrometer-sized zeolite crystals.
abstract: We measured the fluorescence decays and spectra of perylene adsorbed from solution into zeolite X crystals of 2-3 microm in diameter at the level of individual crystals by the application of a microscopy method coupled with a single photon counting apparatus and a multichannel spectrophotometer. We found that both decays and spectra are particle-dependent, i.e. a particle-to-particle difference was observed for the fluorescence decay curves at a fixed loading level along with a particle-dependent spectral change due to the various contribution of excimer emission band relative to those of three monomers. These findings are due to a non-homogeneous distribution which is confirmed by the various emission intensities of perylene-loaded zeolite crystals observed by fluorescence microscopy. Previously, a homogeneous distribution of the guest between zeolite crystals has been just taken for granted and not justified by experiment. The present result suggests that commonly employed collective measurements such as UV-VIS absorption and emission spectroscopies, IR and Raman spectroscopies, and NMR of bulk zeolite powders provide only averaged results and may sometimes suffer from acquiring precise molecular level pictures.
authors.affiliation: Department of Ecosystem Engineering, Graduate School of Engineering, The University of Tokushima, Tokushima-shi, Tokushima, 770-8506, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Ken
authors.initials: K
authors.lastname: Uehara
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sogawa
authors.forename: Mamiko
authors.initials: M
authors.lastname: Takada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fukumura
mesh_terms: D003461:Crystallography; D007700:Kinetics; D008832:Microchemistry / Q000379:methods; D008958:Models, Molecular; D010569:Perylene / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013055:Spectrophotometry, Infrared; D017641:Zeolites / Q000737:chemistry*; D015032:Zinc
chemical_list: D017641:Zeolites; D010569:Perylene; D015032:Zinc