Alkis, S.Okyay, Ali KemalOrtac, B.2015-07-282015-07-282012-01-111932-7447http://hdl.handle.net/11693/13295Blue luminescent colloidal silicon nanocrystals (Si-NCs) were produced in a two-stage process. In the first step, synthesis of Si-NCs was achieved by femtosecond pulsed laser ablation of a silicon wafer, which was immersed in deionized water. The size and the structural and the chemical characteristics of colloidal Si-NCs were investigated by TEM and EDAX analyses, and it is found out that the Si-NCs are in spherical shape and the particle diameters are in the range of 5-100 nm. In the second step, ultrasonic waves and filtering chemical-free post-treatment of colloidal Si-NCs solution was performed to reduce the particle size. High-resolution TEM (HRTEM) studies on post-treated colloidal solution clearly show that small (1-5.5 nm in diameter) Si-NCs were successfully produced. Raman spectroscopy results clearly confirms the generation of Si nanoparticles in the crystalline nature, and the Raman scattering study of post-treated Si-NCs confirms the reduction of the particle size. The UV-vis absorption and photoluminescence (PL) spectroscopy studies elucidate the quantum confinement effect of Si-NCs on the optical properties. The colloidal Si-NCs and post-treated Si-NCs solutions present strong absorption edge shifts toward UV region. Broadband PL emission behavior is observed for the initial colloidal Si-NCs, and the PL spectrum of post-treated Si-NCs presents a blue-shifted broadband PL emission behavior due to the particle size reduction effect.EnglishAbsorption edgesBlue-shiftedChemical characteristicColloidal solutionsCrystalline natureFemtosecond pulsed laser ablationHigh-resolution temLuminescent nanocrystalsParticle diametersParticle size reductionPl emissionPl spectraPost treatmentQuantum confinement effectsSi nanoparticlesSilicon nanocrystalsSpherical shapeTwo-stage processUv regionUv-vis absorptionsArticle10.1021/jp211521k