Identification of C-H Bond Vibration Mode Using Absorption Spectroscopy By A Simple Optically Configured Setup

An optical system model for the identification of Carbon-Hydrogen stretching using spectroscopy is demonstrated and applied to the experiment setup. The optical simulation is achieved using simulation software and performed in a two-mirror system. The optical setup covers a wavelength range of 600 nm to 1200 nm which is a new study based on carbon-hydrogen stretch and test with samples from the alkene group. Significant results of the Carbon-Hydrogen stretch from the alkene group at 1149 nm are detected in Dichloromethane and ethanol. This observation is recorded in real-time and applied in a fast diagnostic system. The isosbestic point of water is measured at 970 nm and useful for our system spectral calibration. The result also shows the ability to quantify the chemical bond of a sample based on two peaks of absorption due to the C-H stretching. This gives a better opportunity for Chemometrics to perform accurately.

Pressure-induced emission enhancement by restricting chemical bond vibration

The effect of intermolecular interactions on intramolecular chemical bonds vibration and luminescence was analyzed. Enhanced intermolecular hydrogen bonds under high pressure suppresses the non-radiative process and result in emission enhancement.

Sonicated-Assisted Acid Treatment of Mordenite Using Acetic Acid

Acid treatment of mordenite was conducted using acetic acid to increase the Si/Al ratio. The acid treatment of mordenite by acetic acid was performed using sonication. The various time of treatments was used to investigate the effect of sonication in acid treatment of mordenite. Mordenite and all samples after treatment were characterized by ICP, FT-IR, XRD, and ammonia adsorption to measure their acidity. The Si/Al ratio of mordenite was increased from 11.33 to 17.31, 19.47, and 20.58 respectively for 3, 6, and 9 h of sonication. This result was supported by the T‒O bond vibration of samples which shift to higher wavenumber. The increase of the Si/Al ratio was followed by the decrease of acidity. The XRD test result revealed partial loss of mordenite framework after acid treatment. The results indicated that the sonication method can be used for acid treatment of mordenite.

Terahertz Spectroscopy for Characterization of Hydrogen Bonding and Cross-linked Structure Dynamics in Polyurethane

Terahertz (THz) absorption spectra of cross-linked polyurethane films were observed at 30–180 °C. The obtained spectra displayed characteristic absorption bands. A band observed at 2.6 THz was assigned to the C=O···N-H hydrogen bond vibration using previously reported data. DFT calculation results confirmed that a band at 7.5 THz arises owing to the torsional vibration of cross-linked molecules containing urethane bonds. The slight changes in the temperature-dependent spectra were analyzed by the first derivative of absorption intensity with temperature. The thermal behavior of absorption intensities indicates the dynamics of hydrogen bonds and cross-linked structures in polyurethane films.

Survey for Transition of Normal Reaction

Transition of reaction is a short-lived unstable molecule in a reaction which is formed in between the reaction when reactants change into products. Whereas, transition state is just the state before formation of new molecule (involves breaking of bonds of reactants and formation of new ones) Transition of reaction differs from a transition state in that the intermediate has a discrete lifetime (be it a few nanoseconds or many days), whereas a transition state lasts for just one bond vibration cycle. Intermediates may be unstable molecules (in which case they are called reactive intermediates) or highly stable molecules. The difference between them can be better described through the energy profile diagram.