Primary quantum yields of NO₂ photodissociation

Abstract

A large discrepancy exists among recent estimates of the primary quantum efficiencies (ϕ1) of nitrogen dioxide photodecomposition, NO2 + hν → NO + O(3P), in the wavelength range from 374 to 396 nm. To resolve this problem, quantum yields of formation of NO, O2, and NO2 loss have been measured for NO2 vapor at low pressures (0.13–0.30 torr) irradiated at selected wavelengths (334.1–404.3 nm) and temperatures (273–370 K). From these data, estimates of ϕ1 were derived which confirm the previous findings of Jones and Bayes (1973b): ϕ1 increases rapidly from near zero at 424 nm to near unity for excitation at λ < 394 nm. The temperature and wavelength dependences of ϕ1 appear to be in qualitative accord with the simple theory of Pitts et al. (1964) that the energy deficiency for photodissociation of NO2 excited at λ > 397.9 nm (λdiss) is made up in large part from the rotational and vibrational energy of the NO2 molecules. Recommended values for ϕ1 based upon a review of these data and estimates made over a period of 58 years, are given as a function of wavelength.

Overview and conclusions of the International Photolysis Frequency Measurement and Modeling Intercomparison (IPMMI) study

“…(b) Cross sections for NO 2 as measured by Harder et al [1997] (blue curve) and Schneider et al [1987] (solid black curve) and recommended by IUPAC (black circles), ratioed to those recommended by JPL [DeMore et al, 1997] and measured by Davidson et al [1988]. (c) Quantum yields of photodissociation of NO 2 as recommended by JPL (DeMore et al [1997] as measured by Gardner et al [1987] for 298 K) (solid black curve), recommended by IUPAC, based on the evaluation of Troe [2000] (dashed black curve), and measured by Roehl et al [1994] for 298 K (red circles) and 248 K (blue circles). Also shown is the ratio of IUPAC to DeMore et al [1997] at 298 K (green dashed curve).…”

“…[60] The most recent quantum yield data for NO 2 photodissociation are shown in Figure A1c; here the recommendations of f values for 298 K of JPL (DeMore et al [1997] from Gardner et al [1987]) are plotted as the solid black curve in Figure A1c, while measurements of f for 298 K by Roehl et al [1994] in the falloff region are shown as the red circles in Figure A1c, and the recommendations of IUPAC (based on the evaluation of Troe [2000]) are shown as the black dashed curve in Figure A1c. The data sets appear to match reasonably well over most of the wavelength range that they have in common.…”

Interferences in photolytic NO&lt;sub&gt;2&lt;/sub&gt; measurements: explanation for an apparent missing oxidant?

“…Eco Physics AG PLC 760), and the averaged measured spectral output of six individual BLC UV-LED arrays of varying running hours. Also shown is the NO 2 quantum yield (Gardner et al, 1987;Koepke et al, 2010). It can be discerned that the UV-LED output overlaps fully with the NO 2 absorption band and the NO 2 quantum yield and is therefore photon-efficient.…”

Light-induced protein nitration and degradation with HONO emission

“…Therefore, in the present study reactions with NO 3 were neglected. Photolysis of NO 2 forming NO (< 400 nm) can also be neglected (Gardner et al, 1987;Roehl et al, 1994) …”