Progress in in-situ dynamic spectrum monitoring of phase change of selenium colloid in solids

[ China Instrument Network Instrument Development ] Recently, Liang Changhao, a researcher at the Nanomaterials and Nanostructure Laboratory of Solid State, based on the self-built "liquid phase metastable nanoparticle in-situ dynamic spectrum analysis platform", selenium (Se) in different solvents Progress has been made in the monitoring of liquid phase in situ dynamic spectroscopy of nanomaterial growth and phase transition, and the relevant research results are published in full text in Applied Surface Science ( Appl . Surf . Sci . 466, 1000-1006 (2019)).

Schematic diagram of preparation, phase transition and in situ spectroscopic monitoring of Se
Realizing the dynamic monitoring and analysis of the intrinsic growth process of metastable nanoparticles is the key to understanding the mechanism of nanocrystal formation, which is an important technical support for the precise preparation and physical property control of nanostructures at the atomic and molecular levels. Although existing liquid phase in situ transmission electron microscopy and in-situ X-ray diffraction techniques have high spatial resolution, they provide an important research method for exploring the nucleation and growth mechanism of nanomaterials in liquid phase systems, but still There are certain limitations, such as low temporal resolution, limited number of samples monitored in situ, etc. In addition, high-energy electron beams or X-rays are added energy sources for metastable nanoparticles, which interfere with the nanocrystals. Significant growth, affecting in-situ dynamic monitoring and analysis.
Based on this, the research team of Liang Changhao, a researcher in the Nanomaterials and Nanostructure Laboratory of Solid State, built a “liquid phase metastable nanoparticle in-situ dynamic spectrum analysis platform” to reveal the size, structure and physical properties of metastable nanoparticles. The variation law provides scientific basis and key technical support for the precise control of nanocrystal growth and the capture of metastable phase by liquid laser ablation technology.
Taking Se colloid as an example, in order to avoid the interference caused by surfactant and reactive residual ions on the growth of nanocrystals, the researchers firstly used liquid laser ablation technology to melt Se target in deionized water to obtain red amorphous form. a-Se nano colloidal solution. Se nanoparticles were then collected by centrifugation and dispersed in three different polar aprotic solvents, dimethylformamide (DMF), acetone (CP) and ethyl acetate (EAC). Using liquid phase in situ Raman spectroscopy monitoring in the platform (Fig. 2), as the aging process progresses, a-Se (252cm-1) gradually decreases in the three solvents, and t-Se (237cm-1) gradually increase. By analyzing the relationship between the intensity of t-Se Raman peak and the aging time, the researchers observed that the phase transition rate of Se in different solvents is different. Among the three solvents, the Se phase transition rate is DMF>CP>EAC. The function of the scatter plot of t-Se (237cm-1) Raman peak intensity and aging time was further fitted. The results show that the phase transition growth rate and time from a-Se to t-Se in different solvents are Power function relationship, and is positively correlated with solvent molecule polarity.
The work was funded by the National Key Basic Research and Development Program of the Ministry of Science and Technology (973 Project), the Chinese Academy of Sciences Equipment Development Project and the National Natural Science Foundation.
(Original title: Progress in in-situ dynamic spectrum monitoring of selenium colloidal phase transitions in solids)

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