The 248 nm photolysis of NO2/N2O4: Time-resolved Fourier transform infrared emission from NO and NO2, and quenching of NO (v=5–8)

Morrell, Claire; Breheny, Ciara; Haverd, Vanessa; Cawley, Aimee; Hancock, Gus

doi:10.1063/1.1521724

Cited by 25 publications

(32 citation statements)

References 27 publications

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“…The major features of the TRFTIR apparatus have been described previously 3,22 and are summarised here. A Lamba-Physik ArF 193 nm excimer laser, generating a 30 mJ pulse in approximately 1 cm 2 , was multipassed in a reaction cell containing either N 2 O or NO 2 (at typical pressures of 1 Torr and 0.1 Torr, respectively) and the quenching gas, together with added Ar, to ensure rotational thermalisation and prevent fly out of the excited species from the observed region.…”

Section: Methodsmentioning

confidence: 99%

Vibrational relaxation of NO (v = 1–16) with NO, N2O, NO2, He and Ar studied by time-resolved Fourier transform infrared emission

Hancock

Morrison

Saunders

2009

Phys. Chem. Chem. Phys.

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Rates of vibrational quenching of NO (v = 1-16) in collisions with a series of quenching species NO, NO2, N2O, He and Ar have been measured at 295 K. NO (v) was formed both by the O(1D) + N2O reaction and the 193 nm photolysis of NO(2), and time-resolved FTIR emission was used to follow the behaviour of the vibrationally excited species. The trends in quenching rate constants can be explained in terms of V-T transfer, V-V transfer and by the effects of competing processes. He and Ar show trends expected from SSH theory, but with relaxation rates that are considerably higher than those expected from previous studies with closed shell molecules, and the influence of non-adiabatic pathways in the relaxation of the NO 2Pi state is discussed. Relaxation with NO2 shows the influence of resonant energy transfer to the nu3 mode, with rate constants peaking at v = 10. For N2O, relaxation rates show essentially a linear increase with v. A linear increase is expected for the change of the transition moment with v for the harmonic oscillator approximation, and when this is taken into account the "reduced probabilities" (defined as P/v, where P is probability of a gas kinetic collision changing the vibrational level from v to v-1) are approximately independent of the energy lost in the NO molecule. The influence of complex formation far from resonance is invoked in both this and for quenching of low vibrational levels by NO2. Finally, self-quenching shows rates which initially decrease with increasing v, but then show a marked increase, with a minimum value at v = 9. Both V-V and V-T processes are believed to occur. Where previously published data are available, general agreement is observed in this study.

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Section: Methodsmentioning

confidence: 99%

Vibrational relaxation of NO (v = 1–16) with NO, N2O, NO2, He and Ar studied by time-resolved Fourier transform infrared emission

Hancock

Morrison

Saunders

2009

Phys. Chem. Chem. Phys.

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“…The major features of the TRFTIR apparatus have been detailed previously 21,22 and are summarised here. A Lambda-Physik (Compex 102) ArF 193 nm excimer laser, operating at 10 Hz with an energy of 100 mJ per pulse and a beam of area 1 cm 2 photolysed the vinyl halide typically at pressures of 50-350 mTorr in the presence of excess Ar to ensure that rotational (but not vibrational) thermalisation of the photolysis products was complete on the time scale of the observations.…”

Section: Methodsmentioning

confidence: 99%

The reaction products of the 193 nm photolysis of vinyl bromide and vinyl chloride studied by time-resolved Fourier transform infrared emission spectroscopy

Carvalho

Hancock

Saunders

2006

Phys. Chem. Chem. Phys.

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Time-resolved Fourier transform infrared (TRFTIR) emission spectroscopy has been used to study the 193 nm photolysis of vinyl bromide (C(2)H(3)Br) and vinyl chloride (C(2)H(3)Cl). Time-resolved IR emission was analysed to obtain nascent vibrational state populations of two primary photolysis products: HBr (v = 1-7) and HCl (v = 1-6). In both cases the nascent vibrational state populations monotonically decrease with increasing v and are in excellent agreement with previously published data. Time-resolved populations were analysed to yield rate constants for vibrational relaxation of HBr (v = 1-3) and HCl (v = 1-4) by parent vinyl bromide and vinyl chloride, respectively. In both cases the rate constants were found to increase with increasing vibrational quantum number, in agreement with a single quantum de-excitation via vibrational to vibrational energy transfer. Butadiene (C(4)H(6)) was identified as a secondary product of the photolysis of both vinyl halides, and shown to be formed from the reaction of parent vinyl halide with the vinyl radical. The presence of a buffer gas was found to produce a strong emission feature centred at 2,200 cm(-1), the intensity of which was dependent on the pressure of the buffer gas used, and whose kinetics are indicative of a secondary reaction product. We propose that this emission is from the vibrational progression of the electronic transition A(0, v, 1) --> X(0, v, 2) in the secondary reaction product C(2)H, whose formation route is favoured by the presence of buffer gas.

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“…The results of studies of the photodissociation of a NO 2 molecule in the ultraviolet wavelength range were considered in [28,29]. It was shown that the distribution of NO fragments over vibrational states during fragmentation of the NO 2 molecule is inverted.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Limiting Sensitivity of the One-Color Laser Fragmentation/Laser-Induced Fluorescence Method in Detection of Nitrobenzene and Nitrotoluene Vapors in the Atmosphere

2019

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The paper presents the results of a numerical evaluation of limiting sensitivity of the method for detecting vapors of nitrocompounds in the atmosphere based on one-color laser fragmentation (LF)/laser-induced fluorescence (LIF) of NO fragments via A2Σ+ (v′ = 0) ← X2Π (v″ = 2) transition. The calculations were performed using the developed kinetic model of the one-color LF/LIF process under consideration. The calculations take into account the influence of ambient nitrogen dioxide as a limiter of the sensitivity of the method when operating in a real atmosphere. It is shown that if the nitrogen dioxide concentration in the atmosphere does not exceed a value of 10 ppb, the maximum detectable vapor concentrations of nitrobenzene and o-nitrotoluene are several ppb. It is also shown that the method of single-frequency one-color excitation usually used for the detection of nitrocompounds does not allow achieving the maximum efficiency of the LF/LIF process.

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The 248 nm photolysis of NO2/N2O4: Time-resolved Fourier transform infrared emission from NO and NO2, and quenching of NO (v=5–8)

Cited by 25 publications

References 27 publications

Vibrational relaxation of NO (v = 1–16) with NO, N2O, NO2, He and Ar studied by time-resolved Fourier transform infrared emission

Vibrational relaxation of NO (v = 1–16) with NO, N2O, NO2, He and Ar studied by time-resolved Fourier transform infrared emission

The reaction products of the 193 nm photolysis of vinyl bromide and vinyl chloride studied by time-resolved Fourier transform infrared emission spectroscopy

Evaluation of Limiting Sensitivity of the One-Color Laser Fragmentation/Laser-Induced Fluorescence Method in Detection of Nitrobenzene and Nitrotoluene Vapors in the Atmosphere

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