Kinetics of the NCN Radical

Baren, Randall E.; Hershberger, John F.

doi:10.1021/jp0208844

Cited by 27 publications

(47 citation statements)

References 45 publications

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“…The outdated, several orders of magnitude higher rate constant estimate from Glarborg et al [13] is not shown. The reported upper limit by Baren and Hershberger (dotted curve) [12], which was based on low-temperature (298-573 K) and lowpressure (ß3 Torr) experiments is not directly comparable with our data but does not contradict our results. The overall agreement with the transition state calculations is rather satisfying.…”

Section: Ncn + Ocontrasting

confidence: 95%

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Shock Tube Measurements of the Rate Constant of the Reaction NCN + O₂

Faßheber

Friedrichs

2015

Int J of Chemical Kinetics

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The rate constant of the comparably slow bimolecular NCN radical reaction NCN + O 2 has been measured for the first time under combustion relevant conditions using the shock tube method. The thermal decomposition of cyanogen azide (NCN 3 ) served as a clean high-temperature source of NCN radicals. NCN concentration-time profiles have been detected by narrow-bandwidth laser absorption atν = 30383.11 cm −1 . The experiments behind incident shock waves have been performed with up to 17% O 2 in the reaction gas mixture. At such high O 2 mole fractions, it was necessary to take O 2 relaxation into account that caused a gradual decrease of the temperature during the experiment. Moreover, following fast decomposition of NCN 3 and collision-induced intersystem crossing of the initially formed singlet NCN to its triplet ground state, an unexpected and slow additional formation of triplet NCN has been observed on a 100-μs timescale. This delayed NCN formation was attributed to a fast recombination of 1 NCN with O 2 forming a 3 NCNOO adduct acting as a reservoir species for NCN. Rate constant data for the reaction NCN + O 2 have been measured at temperatures between 1674 and 2308 K.

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Section: Ncn + Ocontrasting

confidence: 95%

“…for temperatures between 298 and 573 K [12]. In a first attempt to compile a high-temperature NCN mechanism for NO x formation, Glarborg et al estimated a value of k 2 = 1.0 × 10 13 cm 3 mol −1 s −1 [13].…”

Section: Introductionmentioning

confidence: 99%

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O₂

Faßheber

Friedrichs

2015

Int J of Chemical Kinetics

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“…At shorter photolysis wavelengths, also 1 NCN was formed, and a first-order relaxation time of 0.5 ms for 1 NCN was obtained and attributed to phosphorescence [29]. Baren and Hershberger [30] studied the NCN + NO reaction in the gas phase by time-resolved detection of 3 NCN with laser-induced fluorescence (LIF) at 329.008 nm. These authors observed delayed rise times of the 3 NCN fluorescence signals on the order of 15 μs that were attributed to the mechanism of NCN formation via photolysis of CH 2 N 2 /C 2 N 2 mixtures.…”

Section: Ncnmentioning

confidence: 99%

Collisional Relaxation of NCN: An Experimental Study with Laser-Induced Fluorescence

Hetzler

Olzmann

2015

Zeitschrift Für Physikalische Chemie

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Collisional relaxation of NCN produced by photolysis of NCN 3 at a wavelength of 248 nm has been investigated with laser-induced fluorescence (LIF) in a temperature range of 240-293 K and a pressure range of 10-800 mbar with different bath gases (He, Ne, Ar, Kr, H 2 , N 2 , O 2 , and N 2 O). LIF excitation spectra were recorded, and LIF intensity-time profiles experimentally obtained at an excitation wavelength of 329.01 nm have been fitted with biexponential functions. The pressure and bath gas dependence of the rate coefficients obtained was rationalized in terms of a simple Landau-Teller/Schwartz-Slawsky-Herzfeld model, and notable influences of vibrational energy transfer to the rate of the overall relaxation process have been found. Evidence was obtained for a two-channel vibrational relaxation in NCN.

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“…Meanwhile, reaction (1b) has been experimentally proven to be the main product channel of reaction (1) [6][7][8][9][10]. Simultaneously, experimental work on NCN reactions has been carried out [11][12][13][14][15][16][17]. Besides the photolysis of diazomethane (CH 2 N 2 ) in the presence of cyanogen (C 2 N 2 ), the photolysis or pyrolysis of NCN 3 served as a source of NCN radicals.…”

Section: Introductionmentioning

confidence: 99%

A consistent model for the thermal decomposition of NCN₃ and the singlet– triplet relaxation of NCN

Dammeier

Oden

Friedrichs

2012

Int J of Chemical Kinetics

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The thermal decomposition of cyanogen azide (NCN 3 ) and the subsequent collision-induced intersystem crossing (CIISC) process of cyanonitrene (NCN) have been investigated by monitoring excited electronic state 1 NCN and ground state 3 NCN radicals. NCN was generated by the pyrolysis of NCN 3 behind shock waves and by the photolysis of NCN 3 at room temperature. Falloff rate constants of the thermal unimolecular decomposition of NCN 3 in argon have been extracted from 1 NCN concentrationtime profiles in the temperature range 617 K < T < 927 K and at two different total densities: k(ρ ≈ 3 × 10 −6 mol/cm 3 )/s −1 = 4.9 × 10 9 × exp (−71 ± 14 kJ mol −1 /RT ) (±30%); k(ρ ≈ 6 × 10 −6 mol/cm 3 )/s −1 = 7.5 × 10 9 × exp (−71 ± 14 kJ mol −1 /RT ) (±30%). In addition, high-temperature 1 NCN absorption cross sections have been determined in the temperature range 618 K < T < 1231 K and can be expressed by σ/(cm 2 /mol) = 1.0 × 10 8 − 6.3 × 10 4 K −1 × T (±50%). Rate constants for the CIISC process have been measured by monitoring 3 NCN in the temperature range 701 K < T < 1256 K resulting in k CIISC (ρ ≈ 1.8 × 10 −6 mol/cm 3 )/s −1 = 2.6 × 10 6 × exp (−36 ± 10 kJ mol −1 /RT ) (±20%), k CIISC (ρ ≈ 3.5 × 10 −6 mol/cm 3 )/s −1 = 2.0 × 10 6 × exp (−31 ± 10 kJ mol −1 /RT ) (±20%), k CIISC (ρ ≈ 7.0 × 10 −6 mol/cm 3 )/s −1 = 1.4 × 10 6 × exp (−25 ± 10 kJ mol −1 /RT ) (±20%). These values are in good agreement with CIISC rate constants extracted from corresponding 1 NCN measurements. The observed nonlinear pressure dependences reveal a pressure saturation effect of the CIISC process. C 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: [30][31][32][33][34][35][36][37][38][39][40] 2013

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Kinetics of the NCN Radical

Cited by 27 publications

References 45 publications

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O₂

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O₂

Collisional Relaxation of NCN: An Experimental Study with Laser-Induced Fluorescence

A consistent model for the thermal decomposition of NCN₃ and the singlet– triplet relaxation of NCN

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Kinetics of the NCN Radical

Cited by 27 publications

References 45 publications

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O2

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O2

Collisional Relaxation of NCN: An Experimental Study with Laser-Induced Fluorescence

A consistent model for the thermal decomposition of NCN3 and the singlet– triplet relaxation of NCN

Contact Info

Product

Resources

About

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O₂

Shock Tube Measurements of the Rate Constant of the Reaction NCN + O₂

A consistent model for the thermal decomposition of NCN₃ and the singlet– triplet relaxation of NCN