Related Experiment Video
Updated: Aug 29, 2025

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry
Published on: June 14, 2018
Direct Observation and Quantitative Measurement of OH Radical Desorption During the Ultraviolet Photolysis of Liquid
Naoki Numadate1, Shota Saito1, Yuki Nojima2
1Komaba Institute for Science and Department of Basic Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan.
Abstract:
Ultraviolet (UV) photolysis of fatty acid surfactants─which cover the surfaces of atmospheric liquid aerosols and are found in the oceans─such as nonanoic acid (NA) has recently been suggested as a source of hydroxyl (OH) radicals in the troposphere. We used laser-induced fluorescence to directly observe OH radicals desorbed from the surface of neat liquid NA as a primary photoproduct following 213 nm irradiation. The upper limit of photoreaction cross section for the OH radical desorption was estimated to be 9.0(4.1) × 10-22 cm2, which is only 1.2 ± 0.8% of the photoreaction cross section established for the photolysis of gas-phase acetic acid monomers. Vibrational sum-frequency generation spectroscopy for liquid NA revealed the hydrogen-bonded, cyclic, dimer structure of the NA molecules at the liquid surface. This dimerization can inhibit the formation of OH radicals and lead the present low photochemical reactivity of liquid NA.
More Related Videos
Related Concept Videos
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency,...
Radical Autoxidation
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
Radical Formation: Homolysis
Spectroscopy of Carboxylic Acid Derivatives
UV–Vis Spectrometers

