Articles | Volume 8, issue 7
https://doi.org/10.5194/amt-8-2737-2015
https://doi.org/10.5194/amt-8-2737-2015
Research article
 | 
08 Jul 2015
Research article |  | 08 Jul 2015

Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light-emitting diodes

N. D. Rider, Y. M. Taha, C. A. Odame-Ankrah, J. A. Huo, T. W. Tokarek, E. Cairns, S. G. Moussa, J. Liggio, and H. D. Osthoff

Abstract. Photochemical sources of peroxycarboxylic nitric anhydrides (PANs) are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg) lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone) in the presence of a calibrated amount of nitric oxide (NO) and oxygen (O2). In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs) is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC) and thermal dissociation cavity ring-down spectroscopy (TD-CRDS). Using acetone, diethyl ketone (DIEK), diisopropyl ketone (DIPK), or di-n-propyl ketone (DNPK), respectively, the source produces peroxyacetic (PAN), peroxypropionic (PPN), peroxyisobutanoic (PiBN), or peroxy-n-butanoic nitric anhydride (PnBN) from NO in high yield (> 90 %). Box model simulations with a subset of the Master Chemical Mechanism (MCM) were carried out to rationalize product yields and to identify side products. The present work demonstrates that UV-LED arrays are a viable alternative to current Hg lamp setups.

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Short summary
A photochemical source of peroxycarboxylic nitric anhydrides (PANs) in which a dialkyl ketone (acetone, diethyl-, di-isopropyl, or di-n-propyl ketone) in the presence of oxygen and nitric oxide is photodissociated by arrays of ultraviolet light-emitting diodes (UV-LEDs) is described. The source output was analyzed by gas chromatography and thermal dissociation cavity ring-down spectroscopy and modeled using the Master Chemical Mechanism.