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Alkyl‐Functionalized Oxide‐Free Silicon Nanoparticles: Synthesis and Optical Properties
Author(s) -
RossoVasic Milena,
Spruijt Evan,
van Lagen Barend,
De Cola Luisa,
Zuilhof Han
Publication year - 2008
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.200800066
Subject(s) - alkyl , materials science , nanoparticle , dispersity , silicon , monolayer , x ray photoelectron spectroscopy , analytical chemistry (journal) , covalent bond , infrared spectroscopy , spectroscopy , silicon monoxide , molar absorptivity , nanotechnology , chemical engineering , chemistry , polymer chemistry , organic chemistry , optoelectronics , optics , physics , quantum mechanics , engineering
Highly monodisperse silicon nanoparticles (1.57 ± 0.21 nm) are synthesized with a covalently attached alkyl monolayer on a gram scale. Infrared spectroscopy shows that these silicon nanoparticles contain only a few oxygen atoms per nanoparticle. XPS spectra clearly show the presence of unoxidized Si and attached alkyl chains. Owing to the relatively efficient synthesis (yields ≈100‐fold higher than of those previously reported) the molar extinction coefficient ε can be measured: ε max = 1.7 × 10 −4 M −1 cm −1 , only a factor of 4 lower than that of CdS and CdSe nanoparticles of that size. The quantum yield of emission ranges from 0.12 (C 10 H 21 ‐capping) to 0.23 (C 16 H 33 ‐capping). UV/Vis absorption and emission spectroscopy show clear vibrational progressions (974 ± 14 cm −1 ; up to five vibrational bands visible at room temperature), resembling bulk SiC phonons, which support the monodispersity observed by TEM. This was also confirmed by time‐resolved fluorescence anisotropy measurements, which display a strictly monoexponential decay that can only be indicative of monodisperse, ball‐shaped nanoparticles.