Stokes and anti‐Stokes blue light emissions of thermal‐evaporated silica sub‐micron wires

Abstract

Based on the thermal evaporation of silicon monoxide at high temperature, an improved method has been developed for large‐scale synthesis of ultralong amorphous silica sub‐micron wires using polished p‐Si wafers as substrates. The synthesis was done with and without thermite. The morphology and structure of the silica wires was investigated through field‐emission scanning electron microscope equipped with energy dispersive X‐ray spectroscopy, and X‐ray diffractometer. Almost uniform sub‐micron wires with average diameters of 300 nm and length up to hundreds of micrometers were obtained in presence of thermite while sub‐micron wires with many curved segments were obtained in absence of the thermite. Both forms of silica wires emitted blue lights at 478 nm (∼2.6 eV) under excitation at 351 nm (∼3.5 eV), while intense anti‐Stokes blue emissions at 464 nm (∼2.7 eV) were observed under the 694 nm (∼1.8 eV) excitation due to the upconversion effect. This effect is associated with defect centers arising from high oxygen deficiency. The emissions from oxygen deficiency centers might be caused by multistep energy transfer from nonbridging oxygen hole centers to oxygen deficiency centers.

Silica Nanowires Decorated with Cryptophane-A for Sensing Methane

“…The 1 H NMR (CDCl 3 ) data of cryptophane-A were acquired and consistent with the literature values [8]. High-purity silica NWs were synthesized via a modified thermal evaporation of silicon monoxide using polished Si wafer as substrate [12,13]. Thereafter, a drop of the solution of cryptophane-A (0.1 g) dissolved in THF (tetrahydrofuran, 5 ml) was deposited on the (3-aminopropyl)triethoxysilane treated silica NWs on the substrate.…”

Study on up-conversion luminescence and energy transfer of Tb3+, Yb3+, Er3+ doped Gd2O2S phosphor

“…Upconversion luminescence is an anti-Stokes luminescence process. In this process, because the metastable energy level has a long lifetime, the luminous center can colonize the higher energy level by continuously absorbing two or more photons, and finally emit a high-energy photon when returning to the ground state [14]. The practical application of rare earth luminescent materials has been limited by their low luminescent efficiency.…”

Up-Conversion Luminescence and Optical Temperature Sensing of Tb3+, Yb3+, Er3+ Doped (Gd, Y, Lu)2O2S Series Phosphors

“…Up-conversion luminescence is an anti-Stokes luminescence process. In this process, the luminous center can colonize the higher energy level by continuously absorbing two or more photons and finally emit a high-energy photon when returning to the ground state 14 because the metastable energy level has a long lifetime. The optical properties of rare-Earth doped luminescent materials are closely related to the energy transfer process between rare Earth ions.…”