Ozone Cross-Section Measurement by Gas Phase Titration

Abstract

Elevated values of ground-level ozone damage health, vegetation, and building materials and are the subject of air quality regulations. Levels are monitored by networks using mostly ultraviolet (UV) absorption instruments, with traceability to standard reference photometers, relying on the UV absorption of ozone at the 253.65 nm line of mercury. We have redetermined the ozone cross-section at this wavelength based on gas phase titration (GPT) measurements. This is a well-known chemical method using the reaction of ozone (O) with nitrogen monoxide (NO) resulting in nitrogen dioxide (NO) and oxygen (O). The BIPM GPT facility uses state-of-the-art flow measurement, chemiluminescence for NO concentration measurements, a cavity phase shift analyzer (CAPS) for NO measurements, and a UV ozone analyzer. The titration experiment is performed over the concentration range 100-500 nmol/mol, with NO and NO reactants/calibrants diluted down from standards with nominal mole fractions of 50 μmol/mol. Accurate measurements of NO, NO, and O mole fractions allow the calculation of ozone absorption cross section values at 253.65 nm, and we report a value of 11.24 × 10 cm molecule with a relative expanded uncertainty of 1.8% (coverage factor k = 2) based on nitrogen monoxide titration values and a value of 11.22 × 10 cm molecule with a relative expanded uncertainty of 1.4% (coverage factor k = 2) based on nitrogen dioxide titration values. The excellent agreement between these values and recently published absorption cross-section measurements directly on pure ozone provide strong evidence for revising the conventionally accepted value of ozone cross section at 253.65 nm.

Tropospheric Ozone Assessment Report: Tropospheric ozone from 1877 to 2016, observed levels, trends and uncertainties

“…A second ozone standard is gas phase titration of ozone against nitric oxide gas standards. Differences between GPT and standard UV photometry have been investigated by Tanimoto et al (2006) and Viallon et al (2006bViallon et al ( , 2016 and found to be very small (~0.3%) when the newer values of the ozone absorption cross-sections (see Section 2.2.1) are used . Thus GPT supports the proposed decrease in the ozone absorption cross-section at 253.65 nm.…”

Recommendation of a consensus value of the ozone absorption cross-section at 253.65 nm based on a literature review

“…The latter technique involves reacting ozone in air with nitrogen monoxide (NO) and measuring either the loss of NO or the gain of the reaction product, nitrogen dioxide (NO 2 ) to deduce the ozone concentration in the sample. In two independent realizations of the GPT method, a 2%-3% bias in the ozone reference absorption cross-section was observed by the National Institute for Environmental Studies of Japan (NIES) [10] and the BIPM [11], with the two GPT methods reporting higher ozone concentrations than the SRP measurements. The most likely explanation was a systematic deviation in the ozone reference absorption cross-section, which usually represents the major uncertainty component in ozone measurements based on UV photometry.…”

Ozone‐3,6‐dihydroxynaphtha‐2,7‐disulphonate chemiluminescence system is used for online ozone detection

“…Wen developed two methods for detecting ozone based on the electrochemiluminescence resonance energy transfer from Ru(phen) 3 2+ or Ru(bpy) 3 2+ to indigo carmine. [20,21] Nirav Joshi prepared hierarchical NiCo 2 O 4 structure ozone gas sensors with a linear range 28-165 ppbv, [22] Joële Viallon used a NO-O 3 gas-phase titration to detect ozone, [23] Yuya prepared new electrolyte-free ozone sensors using boron-doped diamond electrodes with a detection limit of 1.85 Â 10 À7 M. [24] Chemiluminescence (CL) analysis as a highly sensitive and lowcost method for detecting ozone has been reported. In the nitric oxide-ozone CL method for measuring ozone using the dry and gasphase reactions between NO and O 3 , NO is oxidized by ozone and generates NO 2 in an activated stated NO 2 *, NO 2 * emits a hν when it returned to the lower energy state NO 2 .…”

“…Wen developed two methods for detecting ozone based on the electrochemiluminescence resonance energy transfer from Ru(phen) 3 2+ or Ru(bpy) 3 2+ to indigo carmine. [ 20,21 ] Nirav Joshi prepared hierarchical NiCo 2 O 4 structure ozone gas sensors with a linear range 28–165 ppbv, [ 22 ] Joële Viallon used a NO–O 3 gas‐phase titration to detect ozone, [ 23 ] Yuya prepared new electrolyte‐free ozone sensors using boron‐doped diamond electrodes with a detection limit of 1.85 × 10 −7 M. [ 24 ]…”