Hee-Jung Im

Temperature dependence of fluorescence for EuCl3 in LiCl–KCl eutectic melt

The fluorescence of EuCl(3) in LiCl-KCl eutectic melt according to temperature changes was investigated, and the spontaneous partial reduction of Eu(3+) to Eu(2+) at high temperature was confirmed by the fluorescence results. The fluorescence decreases when the temperature increases, and this was examined in detail. The studies of fluorescence provided information regarding the chemical and physical behavior of europium ions in the molten salt according to the temperature changes. It is applicable for monitoring species and concentrations and estimating the approximate chemical structure of the ions in molten salts.

Classification of materials for explosives from prompt gamma spectra by using principal component analysis

Data from the elemental composition-ratios and experimental prompt gamma spectra of samples were used to develop suitable discriminant classes for suspect samples. The collected data and gamma spectra were applied to principal component analysis (PCA) to discriminate explosives from non-explosive materials.

Explosives Detection Using Deuterium-Deuterium Neutron Generator

Gamma spectra of general and explosive materials were obtained by using the developed neutron induced prompt gamma-ray spectrometry system containing a neutron generator, where the neutron source was created from a deuterium-deuterium reaction, and they were examined to establish whether the samples were explosives or not by using the pattern recognition method. When the gamma spectra of real explosives (or general materials) were projected into the already prepared training set for the pattern recognition, they were placed in the categories of explosives (or general materials) properly.

Investigation of gaseous wet methyl iodide adsorption on Ag nanoparticles embedded in organic–inorganic hybrid silica gels

X-ray photoelectron spectroscopy (XPS), single-particle photoluminescence, and lifetimes were adopted to investigate the interaction properties between gaseous wet methyl iodide (CH3I) and Ag nanoparticles (Ag NPs), which are embedded into a propylethylenediamine (NH2CH2CH2NHCH2CH2CH2-, PEDA) anchored silica gel. Based on the obtained XPS resolutions and shifts of binding energies, a stronger interaction of CH3I than Ag NPs toward SiO2, methylation of amines and silanols by CH3I, the partial interaction in the Ag NPs and CH3I interface, condensation of SiO2 and PEDA, and stabilization of Ag NPs by PEDA were explained. In addition, an enhanced luminescence of Ag NP-embedded PEDA-anchored SiO2 gel (Ag NP-PEDA gel) by surrounding CH3I, and Ag NP stabilization by PEDA and CH3I were also observed from the single-particle photoluminescence and lifetimes.