Related Experiment Video
Updated: Mar 21, 2026

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry
Published on: June 14, 2018
Characterization of Catechins in Water by Photoemission Yield Spectroscopy in Air
Daisuke Yamashita1, Atsushi Ishizaki
1Research and Development Department, Riken Keiki Co., Ltd.
Abstract:
Photoemission yield spectroscopy in air (PYSA) was applied for the characterization of catechins in water in ambient conditions. According to the results of measurements on aqueous solutions of epigallocatechin gallate (EGCg) of various concentrations, the photoemission yield is almost proportional to the concentration of EGCg. Contrarily, the threshold energy of photoemission, EPET, is almost constant at 5.46 ± 0.02 eV. Moreover, we measured aqueous solutions of epicatechin (EC), epigallocatechin (EGC), and epicatechin gallate (ECg). The values of EPET of EC, EGC, ECg were estimated to be 5.72 ± 0.02, 5.68 ± 0.01, and 5.45 ± 0.02 eV, respectively, and a dependence on the molecular structure was found. Furthermore, changes in the photoemission yield spectra of heated EGCg were well explained by molecular orbital calculations on the basis of an assumption of epimerization.
Related Concept Videos
Molecular Spectroscopy: Absorption and Emission
Atomic Emission Spectroscopy: Overview
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
UV–Vis Spectroscopy: Molecular Electronic Transitions
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in...
Atomic Spectroscopy: Absorption, Emission, and Fluorescence

