Photolysis of Nitrogen Dioxide at 3660 and 4047 Å at 25°C

Abstract

Nitrogen dioxide was irradiated at 3660 and 4047 Å at various pressures of NO2, with and without CO2, NO, and N2 as added gases. The data indicate a primary dissociation at 3660 Å and shorter wavelengths corresponding to energies greater than the ON–O bond energy. At 4047 Å, the data are explained by an excited-molecule mechanism. Isotopic oxygen scrambling experiments at 4047 Å indicate the probability of reactions to produce oxygen atoms at that wavelength, but photolysis of NO2 at trace concentrations and high inert-gas pressures indicates that these atoms are not derived from the unimolecular decomposition of the photoactivated molecule. The inhibition of the quantum yield by NO addition was pressure-dependent, lending further support to the premise that oxygen atoms are important in the mechanism at 4047 Å. It is postulated that the reaction NO2*+NO2→N2O3+O is the source of atomic oxygen.

Influence of photolysis on multispectral photoacoustic measurement of nitrogen dioxide concentration

“…As the wavelength is increased beyond about 430 nm, into the third wavelength region (430 nm < l < 630 nm), internal energy and relative kinetic energy cannot offer sufficient additional energy to break the NO 2 molecule. In this region, photolysis is caused by the reaction of an electronically excited NO 2 molecule with a ground state NO 2 molecule, as shown in eq 3 (Norrrish, 1929a(Norrrish, , 1929b, or by an alternative reaction shown in eq 4 (Ford and Jaffe, 1963).…”

Product Quantum Yields from the Photolysis of NO2 at 366 nm in the Presence of Ethylene. ‐ The Role of NO3*

“…Ford and Jaffe [4] reported that I$(-NO,) is quite dependent on p(N0,) at the lower pressures. At NO, partial pressure above 13 mbar the equilibrium 2 N 0 , NzO4 must be considered.…”

“…As can be seen in I, 11, and 111). The other literature value for k,/k, (0.002 mol/l [4]) only gives meaningful values with the above equation when k, 2 10" I/mol . 3).…”

“…At NO, partial pressure above 13 mbar the equilibrium 2 N 0 , NzO4 must be considered. We calculated the light intensity lo of the Hg lamp, which experimentally was observed to remain constant within 3% for a period of several hours, taking $(-NO,) = 1.95 [34], and alternatively the equation from Ford and Jaffe [4] $( -NOJ' Because of the diversity of the required analytical procedures in those runs in which NO, was photolysed in the presence of ethylene, the experiments were limited to essentially three experimental conditions (EC). It will regenerate, via an equilibrium displacement to the left, some of the photolytically consumed NO2.…”

“…(b(0,) has not been measured previously in the NO,/C,H, system. s [2,5], and k, (k3/k4 = 0.01 [3], and 0.002 mol/l [4]). lo9 [2], 9.5. lo9 [38], and 5.10'' I/mol.…”