TY - JOUR
T1 - Kinetic Study of the Reactions PO + O2 and PO2 + O3 and Spectroscopy of the PO Radical
AU - Douglas, Kevin M.
AU - Blitz, Mark A.
AU - Mangan, Thomas P.
AU - Western, Colin M.
AU - Plane, John M.C.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - The kinetics of the reactions of PO with O2 and PO2 with O3 were studied at temperatures ranging from ∼190 to 340 K, using a pulsed laser photolysis-laser induced fluorescence technique. For the reaction of PO + O2, there is evidence of both a two- and three-body exit channel, producing PO2 + O and PO3, respectively. Potential energy surfaces of both the PO + O2 and PO2 + O3 systems were calculated using electronic structure theory and combined with RRKM calculations to explain the observed pressure and temperature dependences. For PO + O2, at pressures typical of a planetary upper atmosphere where meteoric ablation of P will occur, the reaction is effectively pressure independent with a yield of PO2 + O of >99%; the rate coefficient can be expressed by log10(k, 120-500 K, cm3 molecule-1 s-1) = -13.915 + 2.470 log10(T) - 0.5020(log10(T))2, with an uncertainty of ±10% over the experimental temperature range (191-339 K). With increasing pressure, the yield of PO3 increases, reaching ∼90% at a pressure of 1 atm and T = 300 K. For PO2 + O3, k(188-339 K) = 3.7 × 10-11 exp(-1131/T) cm3 molecule-1 s-1, with an uncertainty of ±26% over the stated temperature range. Laser-induced fluorescence spectra of PO over the wavelength range 245-248 nm were collected and simulated using pgopher to obtain new spectroscopic constants for the ground and v = 1 vibrational levels of the X2Π and A2Σ+ states of PO.
AB - The kinetics of the reactions of PO with O2 and PO2 with O3 were studied at temperatures ranging from ∼190 to 340 K, using a pulsed laser photolysis-laser induced fluorescence technique. For the reaction of PO + O2, there is evidence of both a two- and three-body exit channel, producing PO2 + O and PO3, respectively. Potential energy surfaces of both the PO + O2 and PO2 + O3 systems were calculated using electronic structure theory and combined with RRKM calculations to explain the observed pressure and temperature dependences. For PO + O2, at pressures typical of a planetary upper atmosphere where meteoric ablation of P will occur, the reaction is effectively pressure independent with a yield of PO2 + O of >99%; the rate coefficient can be expressed by log10(k, 120-500 K, cm3 molecule-1 s-1) = -13.915 + 2.470 log10(T) - 0.5020(log10(T))2, with an uncertainty of ±10% over the experimental temperature range (191-339 K). With increasing pressure, the yield of PO3 increases, reaching ∼90% at a pressure of 1 atm and T = 300 K. For PO2 + O3, k(188-339 K) = 3.7 × 10-11 exp(-1131/T) cm3 molecule-1 s-1, with an uncertainty of ±26% over the stated temperature range. Laser-induced fluorescence spectra of PO over the wavelength range 245-248 nm were collected and simulated using pgopher to obtain new spectroscopic constants for the ground and v = 1 vibrational levels of the X2Π and A2Σ+ states of PO.
UR - http://www.scopus.com/inward/record.url?scp=85092682547&partnerID=8YFLogxK
U2 - 10.1021/acs.jpca.0c06106
DO - 10.1021/acs.jpca.0c06106
M3 - Article (Academic Journal)
C2 - 32877605
AN - SCOPUS:85092682547
SN - 1089-5639
VL - 124
SP - 7911
EP - 7926
JO - The journal of physical chemistry. A
JF - The journal of physical chemistry. A
IS - 39
ER -