REACTION OF N2(A3∑U+) WITH ATOMIC NITROGEN

1966 ◽  
Vol 44 (10) ◽  
pp. 1171-1174 ◽  
Author(s):  
Robert A. Young
Keyword(s):  
Excited States ◽  
Rate Coefficient ◽  
Atomic Nitrogen ◽  
Active Nitrogen ◽  
Upper Limit ◽  
Interchange Process

Attempts to measure the actual lifetime of N2(A3∑u+) in active nitrogen resulted only in a very small upper limit of ≈5 × 10−4 s. This result is consistent with quenching of the A3∑u+ state by atomic nitrogen in an atom–atom interchange process,[Formula: see text]having a rate coefficient of [Formula: see text] It is suggested that similar processes are involved in determining the distribution of excited states observed in atom association.

scholarly journals Direct Kinetic Measurements and Master Equation Modelling of the Unimolecular Decomposition of Resonantly-Stabilized CH2CHCHC(O)OCH3 Radical and an Upper Limit Determination for CH2CHCHC(O)OCH3 + O2 Reaction

2020 ◽  
Vol 234 (7-9) ◽  
pp. 1251-1268 ◽  
Author(s):  
Satya Prakash Joshi ◽  
Prasenjit Seal ◽  
Timo Theodor Pekkanen ◽  
Raimo Sakari Timonen ◽  
Arrke J. Eskola
Keyword(s):  
Master Equation ◽  
Density Functional ◽  
Rate Coefficient ◽  
Decomposition Kinetics ◽  
Basis Sets ◽  
Stationary Points ◽  
Unimolecular Decomposition ◽  
Kinetic Measurements ◽  
Point Energy ◽  
Upper Limit

AbstractMethyl-Crotonate (MC, (E)-methylbut-2-enoate, CH3CHCHC(O)OCH3) is a potential component of surrogate fuels that aim to emulate the combustion of fatty acid methyl ester (FAME) biodiesels with significant unsaturated FAME content. MC has three allylic hydrogens that can be readily abstracted under autoignition and combustion conditions to form a resonantly-stabilized CH2CHCHC(O)OCH3 radical. In this study we have utilized photoionization mass spectrometry to investigate the O2 addition kinetics and thermal unimolecular decomposition of CH2CHCHC(O)OCH3 radical. First we determined an upper limit for the bimolecular rate coefficient of CH2CHCHC(O)OCH3 + O2 reaction at 600 K (k ≤ 7.5 × 10−17 cm3 molecule−1 s−1). Such a small rate coefficient suggest this reaction is unlikely to be important under combustion conditions and subsequent efforts were directed towards measuring thermal unimolecular decomposition kinetics of CH2CHCHC(O)OCH3 radical. These measurements were performed between 750 and 869 K temperatures at low pressures (<9 Torr) using both helium and nitrogen bath gases. The potential energy surface of the unimolecular decomposition reaction was probed at density functional (MN15/cc-pVTZ) level of theory and the electronic energies of the stationary points obtained were then refined using the DLPNO-CCSD(T) method with the cc-pVTZ and cc-pVQZ basis sets. Master equation simulations were subsequently carried out using MESMER code along the kinetically important reaction pathway. The master equation model was first optimized by fitting the zero-point energy corrected reaction barriers and the collisional energy transfer parameters $\Delta{E_{{\text{down}},\;{\text{ref}}}}$ and n to the measured rate coefficients data and then utilize the constrained model to extrapolate the decomposition kinetics to higher pressures and temperatures. Both the experimental results and the MESMER simulations show that the current experiments for the thermal unimolecular decomposition of CH2CHCHC(O)OCH3 radical are in the fall-off region. The experiments did not provide definite evidence about the primary decomposition products.

THE REACTION OF ACTIVE NITROGEN WITH PROPYLENE

1952 ◽  
Vol 30 (12) ◽  
pp. 915-921 ◽  
Author(s):  
G. S. Trick ◽  
C. A. Winkler
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Hydrogen Cyanide ◽  
Atomic Hydrogen ◽  
Atomic Nitrogen ◽  
Active Nitrogen

The reaction of nitrogen atoms with propylene has been found to produce hydrogen cyanide and ethylene as the main products, together with smaller amounts of ethane and propane and traces of acetylene and of a C4 fraction. With excess propylene, the nitrogen atoms were completely consumed and for the reaction at 242 °C., 0.77 mole of ethylene was produced for each mole of excess propylene added. For reactions at lower temperatures, less ethylene was produced. The proposed mechanism involves formation of a complex between the nitrogen atom and the double bond of propylene, followed by decomposition to ethylene, hydrogen cyanide, and atomic hydrogen. The ethylene would then react with atomic nitrogen in a similar manner.

The radiation-induced formation of excited states of aromatic hydrocarbons in alicyclic hydrocarbons I. Yields of excited singlet and triplet state solute molecules

1975 ◽  
Vol 347 (1648) ◽  
pp. 61-73 ◽  
Keyword(s):  
Energy Transfer ◽  
Excited States ◽  
Pulse Radiolysis ◽  
Minor Role ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Excited Triplet ◽  
Upper Limit ◽  
Radiation Induced ◽  
A Minor

The dependences on concentration of the yield of excited triplet naphthalene, G ( 3 Naph٭), and of the radiation-induced fluorescence obtained on pulse radiolysis of solutions of naphthalene in cyclopentane, cyclooctane and decalin are reported. The yields of singlet excited naphthalene, G( 1 Naph٭), formed on pulse radiolysis of these solutions have been determined by comparing the intensity of the radiation-induced fluorescence with that obtained on photo excitation and the extent of formation of 3 Naph٭ by intersystem crossing, G ( 3 Naph٭) i. s. c., is assessed. Upper limit yields of solvent excited states, G ( 1 RH٭), were determined by measuring the extent of singlet energy transfer to toluene. It is concluded that energy transfer from solvent excited states plays a minor role in the formation of excited states of aromatic solutes.

THE REACTIONS OF ACTIVE NITROGEN WITH THE BUTANES

1954 ◽  
Vol 32 (7) ◽  
pp. 718-724 ◽  
Author(s):  
R. A. Back ◽  
C. A. Winkler
Keyword(s):  
Nitrogen Atom ◽  
Rate Constants ◽  
Hydrogen Cyanide ◽  
Main Product ◽  
Activation Energies ◽  
Reactive Species ◽  
Atomic Nitrogen ◽  
Initial Attack ◽  
Active Nitrogen ◽  
Rate Controlling Step

The main product of the reactions of active nitrogen with n- and iso-butanes at 75 °C. and 250 °C. was hydrogen cyanide. Small amounts of C2 hydrocarbons, mainly ethylene and acetylene, were produced in both reactions. Second order rate constants were calculated on the assumption that the reactive species in active nitrogen is atomic nitrogen, and that the initial attack of a nitrogen atom is the rate-controlling step. The activation energies were then estimated to be 3.6 kcal. and 3.1 kcal. and the probability factors 4.5 × 10−4 and 4.4 × 10−4, for the n-butane and isobutane reactions respectively.

Upper Limit for the Lifetimes of Excited States ofNi60

1955 ◽  
Vol 97 (2) ◽  
pp. 561-563 ◽  
Author(s):  
Z. Bay ◽  
V. P. Henri ◽  
F. McLernon
Keyword(s):  
Excited States ◽  
Upper Limit

Upper Limit for the Rate Coefficient for the Reaction HO2 + NO2 .fwdarw. HONO + O2

1995 ◽  
Vol 29 (1) ◽  
pp. 202-206 ◽  
Author(s):  
Geoffrey S. Tyndall ◽  
John J. Orlando ◽  
Jack G. Calvert
Keyword(s):  
Rate Coefficient ◽  
Upper Limit

scholarly journals Influence of Active Nitrogen Species on the Nitridation Rate of Sapphire

1998 ◽  
Vol 537 ◽  
Author(s):  
A.J. Ptak ◽  
K.S. Ziemer ◽  
M.R. Millecchia ◽  
C.D. Stinespring ◽  
T.H. Myers
Keyword(s):  
Molecular Nitrogen ◽  
Active Species ◽  
Operating Conditions ◽  
Rf Plasma ◽  
Atomic Nitrogen ◽  
Active Nitrogen ◽  
Plasma Sources ◽  
Electrostatic Deflector ◽  
Low Energy Ions ◽  
Operating Regimes

AbstractThe operating regimes of two rf-plasma sources, an Oxford CARS-25 and an EPI Unibulb, have been extensively characterized. By changing the exit aperture configuration and using an electrostatic deflector, the Oxford source could produce either primarily atomic nitrogen, atomic nitrogen mixed with low energy ions, or a large flux of higher energy ions (>65eV) as the active species in a background of neutral molecular nitrogen. The EPI source produced a significant flux of metastable molecular nitrogen as the active species with a smaller atomic nitrogen component. Nitridation of sapphire using each source under the various operating conditions indicate that the reactivity was different for each type of active nitrogen. Boron contamination originating from the pyrolytic boron nitride plasma cell liner was observed.

scholarly journals SiO Masers in the Star Forming Regions W51 IRS2 and Sgr B2 MD5

1987 ◽  
Vol 115 ◽  
pp. 178-178
Author(s):  
N. Ukita ◽  
T. Hasegawa ◽  
N. Kaifu ◽  
K.-I. Morita ◽  
S. Okumura ◽  
...  
Keyword(s):  
Star Formation ◽  
Excited States ◽  
Line Intensity ◽  
Massive Star ◽  
Massive Star Formation ◽  
Vibrationally Excited ◽  
Maser Emission ◽  
Star Forming ◽  
Star Forming Regions ◽  
Upper Limit

The maser emission of the J = 1-0 lines of SiO in vibrationally excited states has been detected in two regions of massive star formation, W51 IRS2 and Sgr B2 MD5. The SiO masers apparently coincide with strong H2O masers in each source within the uncertainties of < 5″. Their velocity ranges fall within those of the nearest H2O masers (Figure 1). In W51 IRS2 the maser emission is observed only in the v = 2 state, and the upper limit of the v = 1 line (3σ) is 1/15th of the v = 2 line intensity. The v = 1 emission found in Sgr B2 MD5 is five times stronger than the marginally detected v = 2 emission (Figure 2). Their luminosities are comparable to those from the corresponding maser in Orion.

Infrared emission by active nitrogen II. The kinetic behaviour of N 2 (B 3 n II 2 )

1975 ◽  
Vol 346 (1644) ◽  
pp. 121-137 ◽  
Keyword(s):  
Rate Coefficient ◽  
Infrared Emission ◽  
Active Nitrogen ◽  
Kinetic Behaviour ◽  
Low Levels ◽  
Low Pressures ◽  
Kinetics Of

The kinetics of the emission of low levels (v = 0- 4) of N2(B3IIg) in active nitrogen have been studied in nitrogen and in argon carriers. In argon carriers at low pressures, these levels are populated by emission of the Y bands N2(B '32^->-B3IIg) and the 1+ bands (B 3IIg->A 3i ;!,v = 7- 13) followed by collision induced transitions to the B state for which the rate coefficient is found to be ca. 2 x 10-13 cm3 molecule-1 s-1. In nitrogen carriers the efficient quenching of N 2 (B) and N 2 (B') by N 2 produces a somewhat similar population of N 2 (A) and N 2 (B). The dependence of the emission kinetics on [N] and its quenching by C0 2 are shown to arise from removal of the N 2 (A) precursor by N or by C0 2.

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