Molecular insights into reversible redox sites in solid-phase humic substances as examined by electrochemical in situ FTIR and two-dimensional correlation spectroscopy

2018 ◽  
Vol 494 ◽  
pp. 136-143 ◽  
Author(s):  
Yong Yuan ◽  
Xixi Cai ◽  
Bin Tan ◽  
Shungui Zhou ◽  
Baoshan Xing
Keyword(s):  
Humic Substances ◽  
Solid Phase ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
In Situ Ftir ◽  
Redox Sites ◽  
Reversible Redox

scholarly journals Acrylamide precipitation polymerization in a continuous flow reactor: an in situ FTIR study reveals kinetics

2020 ◽  
Author(s):  
Pascal Fandrich ◽  
Lars Wiehemeier ◽  
Maxim Dirksen ◽  
Oliver Wrede ◽  
Tilman Kottke ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Monomer Conversion ◽  
Precipitation Polymerization ◽  
Correlation Spectroscopy ◽  
In Situ Monitoring ◽  
In Situ Ftir ◽  
Absorption Bands ◽  
Continuous Flow Reactor

AbstractIn this work, we present a combination of a continuous flow reactor with in situ monitoring of the monomer conversion in a precipitation polymerization. The flow reactor is equipped with a preheating area for the synthesis of thermoresponsive microgels, based on N-isopropylacrylamide (NIPAM). The reaction progress is monitored with in situ FTIR spectroscopy. The monomer conversion at defined residence times is determined from absorbance spectra of the reaction solutions by linear combination with reference spectra of the stock solution and the purified microgel. The reconstruction of the spectra appears to be in good agreement with experimental data in the range of 1710 to 1530 cm− 1, in which prominent absorption bands are used as probes for the monomer and the polymer. With increasing residence time, we observed a decrease in intensity of the ν(C=C) vibration, originating from the monomer, while the ν(C=O) vibration is shifted to higher frequencies by polymerization. Differences between the determined inline conversion kinetics and offline growth kinetics, determined by photon correlation spectroscopy (PCS), are discussed in terms of diffusion and point to a crucial role of mixing in precipitation polymerizations.

Microdynamic changes of moisture-induced crystallization of amorphous calcium carbonate revealed via in situ FTIR spectroscopy

2019 ◽  
Vol 21 (39) ◽  
pp. 21882-21889 ◽  
Author(s):  
Meng Cheng ◽  
Shengtong Sun ◽  
Peiyi Wu
Keyword(s):  
Calcium Carbonate ◽  
Correlation Analysis ◽  
Ftir Spectroscopy ◽  
Two Dimensional ◽  
In Situ Ftir ◽  
Amorphous Calcium Carbonate ◽  
In Situ Ftir Spectroscopy ◽  
Induced Crystallization

A microdynamic mechanism of moisture-induced ACC crystallization involving three consecutive conversion stages is elucidated via in situ FTIR spectroscopy and two-dimensional correlation analysis.

Dynamic studies of silicide-mediated crystallization of amorphous silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1352-1353
Author(s):  
C. Hayzelden ◽  
J. L. Batstone
Keyword(s):  
Ion Implantation ◽  
Solid Phase ◽  
Metallic Phase ◽  
Single Crystal Substrate ◽  
Free Electrons ◽  
Melt Temperature ◽  
Transmission Electron ◽  
Crystal Substrate ◽  
High Resolution Tem

Epitaxial reordering of amorphous Si(a-Si) on an underlying single-crystal substrate occurs well below the melt temperature by the process of solid phase epitaxial growth (SPEG). Growth of crystalline Si(c-Si) is known to be enhanced by the presence of small amounts of a metallic phase, presumably due to an interaction of the free electrons of the metal with the covalent Si bonds near the growing interface. Ion implantation of Ni was shown to lower the crystallization temperature of an a-Si thin film by approximately 200°C. Using in situ transmission electron microscopy (TEM), precipitates of NiSi2 formed within the a-Si film during annealing, were observed to migrate, leaving a trail of epitaxial c-Si. High resolution TEM revealed an epitaxial NiSi2/Si(l11) interface which was Type A. We discuss here the enhanced nucleation of c-Si and subsequent silicide-mediated SPEG of Ni-implanted a-Si.Thin films of a-Si, 950 Å thick, were deposited onto Si(100) wafers capped with 1000Å of a-SiO2. Ion implantation produced sharply peaked Ni concentrations of 4×l020 and 2×l021 ions cm−3, in the center of the films.

Sign in / Sign up

Export Citation Format

Share Document