Measurements of the absolute concentrations of hydrogen atom and hydroxyl produced in the silyl + oxygen reaction: determination of the product branching ratios

1993 ◽  
Vol 97 (17) ◽  
pp. 4473-4478 ◽  
Author(s):  
Mitsuo Koshi ◽  
Nobuhiro Nishida ◽  
Yoshinori Murakami ◽  
Hiroyuki Matsui
Keyword(s):  
Hydrogen Atom ◽  
Branching Ratios ◽  
Absolute Concentrations ◽  
The Absolute ◽  
Product Branching ◽  
Oxygen Reaction

Determination of the rate constant and of product branching ratios in the reaction of CH3O2 with OCl between 233 and 300 K

1994 ◽  
Vol 98 (10) ◽  
pp. 1298-1302 ◽  
Author(s):  
A. S. Kukui ◽  
T. P. W. Jungkamp ◽  
R. N. Schindler
Keyword(s):  
Rate Constant ◽  
Branching Ratios ◽  
Product Branching

Determination of Absolute Product Branching Ratios in Mass Spectrometric Experiments:  Detecting Acetyl Radicals at CH2CO+

1996 ◽  
Vol 100 (13) ◽  
pp. 5200-5204 ◽  
Author(s):  
D. C. Kitchen ◽  
T. L. Myers ◽  
L. J. Butler
Keyword(s):  
Branching Ratios ◽  
Mass Spectrometric ◽  
Product Branching

Determination of the Rates of Hydrogen Atom Reaction with NO by a Modulation Technique

1973 ◽  
Vol 51 (3) ◽  
pp. 370-372 ◽  
Author(s):  
R. Atkinson ◽  
R. J. Cvetanović
Keyword(s):  
Nitric Oxide ◽  
Hydrogen Atom ◽  
Phase Shift ◽  
Rate Constants ◽  
Hydrogen Atoms ◽  
Arrhenius Parameters ◽  
Modulation Technique ◽  
The Absolute

A modulation technique has been used to determine from phase shift measurements the absolute values of the rate constants and the Arrhenius parameters of the reaction of hydrogen atoms with nitric oxide.

Determination of the absolute concentrations of mono amine oxidase A and B in human tissues

1989 ◽  
Vol 38 (6) ◽  
pp. 901-905 ◽  
Author(s):  
Anne-Marie O'Carroll ◽  
Mary C. Anderson ◽  
Iqdam Tobbia ◽  
Jack P. Phillip ◽  
Keith F. Tipton
Keyword(s):  
Amine Oxidase ◽  
Human Tissues ◽  
Absolute Concentrations ◽  
The Absolute

scholarly journals Formation Mechanism of a Nonterrestrial C6H Radical: An Ab Initio/RRKM Study on the Reaction of Tetracarbon with Acetylene

2019 ◽  
Author(s):  
Tong Zhu ◽  
Chih-Hao Chin ◽  
John ZH Zhang
Keyword(s):  
Hydrogen Atom ◽  
Ab Initio ◽  
Rate Constants ◽  
Kinetic Equations ◽  
Branching Ratios ◽  
The Other ◽  
Formation Mechanisms ◽  
Hydrogen Elimination ◽  
Carbon Carbon Bond ◽  
Product Branching

This study examined the formation mechanisms of singlet (rhombic) and triplet (linear) C4 with acetylene by using accurate ab initio CCSD(T)/cc-pVTZ/B3LYP/6-311G(d,p) calculations, followed by a kinetic analysis of various reaction pathways and computations of relative product yields in combustion and planetary atmospheres. These calculations were combined with the Rice–Ramsperger–Kassel–Marcus (RRKM) calculations of reaction rate constants for predicting product-branching ratios, which depend on the collision energy under single-collision conditions. The results show that the initial reaction begins with the formation of an intermediate t-i2, with entrance barriers of 3.8 kcal/mol, and an intermediate s-i1 without entrance barriers. On the triplet surface, the t-i2 rearranged the other C6H2 isomers, including t-i3, t-i4, and t-i6, through hydrogen migration; the t-i2, t-i3, t-i4, t-i5, and t-i6 isomers lost a hydrogen atom, and produced the most stable linear isomer of C6H, with an overall reaction exothermicity of 11 kcal/mol. Hydrogen elimination from the t-i10 isomer led to the formation of the annular C6H isomer, HC3C3 + H, at 23.9 kcal/mol above l-C4 + C2H2. On the singlet surfaces, s-i1 rearranged the other C6H2 isomers, including s-i2 and s-i4, through carbon–carbon bond cleavage. The s-i6 and s-i11 isomers also lost a hydrogen atom, and produced the linear C6H radical. Hydrogen elimination from the s-i4 isomer led to the formation of the annular C6H isomer. The s-i5 lost a hydrogen atom, and produced the six-member ring c-C6H isomer, at 2.1 kcal/mol higher than l-C4 + C2H2. The 1,1-H2 loss from the s-i10 isomer produced the linear hexacarbon l-C6 + H2 product, with an endothermicity of 2.3 kcal/mol and a 1,1-H2 loss from the s-i11 isomer, producing in the cyclic hexacarbon c-C6 + H2 product, with an exothermicity of 11.2 kcal/mol. The product-branching ratios obtained by solving kinetic equations with individual rate constants calculated using the RRKM and VTST theories for determining the collision energies between 5 kcal/mol and 25 kcal/mol show that l-C6H + H is the dominant reaction product, whereas HC3C3 + H, l-C6 + H2, c-C6H + H, and c-C6 + H2 are minor products with branching ratios. The s-i6 isomer was calculated to be the most stable C6H2 species, even more favorable than t-i3 (by 76 kcal/mol).

scholarly journals Formation Mechanism of a Nonterrestrial C6H Radical: An Ab Initio/RRKM Study on the Reaction of Tetracarbon with Acetylene

2019 ◽  
Author(s):  
Tong Zhu ◽  
Chih-Hao Chin ◽  
John ZH Zhang
Keyword(s):  
Hydrogen Atom ◽  
Ab Initio ◽  
Rate Constants ◽  
Kinetic Equations ◽  
Branching Ratios ◽  
The Other ◽  
Formation Mechanisms ◽  
Hydrogen Elimination ◽  
Carbon Carbon Bond ◽  
Product Branching

This study examined the formation mechanisms of singlet (rhombic) and triplet (linear) C4 with acetylene by using accurate ab initio CCSD(T)/cc-pVTZ/B3LYP/6-311G(d,p) calculations, followed by a kinetic analysis of various reaction pathways and computations of relative product yields in combustion and planetary atmospheres. These calculations were combined with the Rice–Ramsperger–Kassel–Marcus (RRKM) calculations of reaction rate constants for predicting product-branching ratios, which depend on the collision energy under single-collision conditions. The results show that the initial reaction begins with the formation of an intermediate t-i2, with entrance barriers of 3.8 kcal/mol, and an intermediate s-i1 without entrance barriers. On the triplet surface, the t-i2 rearranged the other C6H2 isomers, including t-i3, t-i4, and t-i6, through hydrogen migration; the t-i2, t-i3, t-i4, t-i5, and t-i6 isomers lost a hydrogen atom, and produced the most stable linear isomer of C6H, with an overall reaction exothermicity of 11 kcal/mol. Hydrogen elimination from the t-i10 isomer led to the formation of the annular C6H isomer, HC3C3 + H, at 23.9 kcal/mol above l-C4 + C2H2. On the singlet surfaces, s-i1 rearranged the other C6H2 isomers, including s-i2 and s-i4, through carbon–carbon bond cleavage. The s-i6 and s-i11 isomers also lost a hydrogen atom, and produced the linear C6H radical. Hydrogen elimination from the s-i4 isomer led to the formation of the annular C6H isomer. The s-i5 lost a hydrogen atom, and produced the six-member ring c-C6H isomer, at 2.1 kcal/mol higher than l-C4 + C2H2. The 1,1-H2 loss from the s-i10 isomer produced the linear hexacarbon l-C6 + H2 product, with an endothermicity of 2.3 kcal/mol and a 1,1-H2 loss from the s-i11 isomer, producing in the cyclic hexacarbon c-C6 + H2 product, with an exothermicity of 11.2 kcal/mol. The product-branching ratios obtained by solving kinetic equations with individual rate constants calculated using the RRKM and VTST theories for determining the collision energies between 5 kcal/mol and 25 kcal/mol show that l-C6H + H is the dominant reaction product, whereas HC3C3 + H, l-C6 + H2, c-C6H + H, and c-C6 + H2 are minor products with branching ratios. The s-i6 isomer was calculated to be the most stable C6H2 species, even more favorable than t-i3 (by 76 kcal/mol).

Polarity Determination in Sphalerite and Wurtzite Structures

1990 ◽  
Vol 48 (2) ◽  
pp. 500-501
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Opposite Polarity ◽  
Single Domain ◽  
Polar Material ◽  
Electron Microscopic ◽  
Dynamical Interaction ◽  
X Ray ◽  
Polarity Determination ◽  
The Absolute ◽  
Microscopic Techniques

The determination of the absolute polarity of a polar material is often crucial to the understanding of the defects which occur in such materials. Several methods exist by which this determination may be performed. In bulk, single-domain specimens, macroscopic techniques may be used, such as the different etching behavior, using the appropriate etchant, of surfaces with opposite polarity. X-ray measurements under conditions where Friedel’s law (which means that the intensity of reflections from planes of opposite polarity are indistinguishable) breaks down can also be used to determine the absolute polarity of bulk, single-domain specimens. On the microscopic scale, and particularly where antiphase boundaries (APBs), which separate regions of opposite polarity exist, electron microscopic techniques must be employed. Two techniques are commonly practised; the first [1], involves the dynamical interaction of hoLz lines which interfere constructively or destructively with the zero order reflection, depending on the crystal polarity. The crystal polarity can therefore be directly deduced from the relative intensity of these interactions.

Determination of the absolute configuration of natural products

2014 ◽  
Vol 11 (3) ◽  
pp. 193-198 ◽  
Author(s):  
Ling-Yi KONG ◽  
Peng WANG
Keyword(s):  
Natural Products ◽  
Absolute Configuration ◽  
The Absolute

Convergence Properties of Quasiclassical Trajectory Calculations on Dynamics of Autoionization Event in He(23S)-D2 Penning Ionization

1997 ◽  
Vol 62 (2) ◽  
pp. 154-171 ◽  
Author(s):  
Jan Vojtík ◽  
Richard Kotal
Keyword(s):  
Branching Ratios ◽  
Classical Trajectory ◽  
Vibrational States ◽  
Penning Ionization ◽  
Trajectory Calculations ◽  
Quantum Mechanical Treatment ◽  
Total Ionization ◽  
Vibrational Levels ◽  
Degree Of Convergence ◽  
Product Branching

An analysis of the degree of convergence of theoretical pictures of the dynamics of the autoionization event He(23S)-D2(v" = 0) -> [He...D2+(v')] + e is presented for a number of batches of Monte Carlo calculations differing in the number of the trajectories run. The treatment of the dynamics consists in 2D classical trajectory calculations based on static characteristics which include a quantum mechanical treatment of the perturbed D2(v" = 0) and D2+(v') vibrational motion. The vibrational populations are dynamical averages over the local widths of the He(23S)-D2(v" = 0) state with respect to autoionization to D2+(...He) in its v'th vibrational level and the Penning electron energies are related to the local differences between the energies of the corresponding perturbed D2(v" = 0)(...He*) and D2+(v')(...He) vibrational states. Special attention is paid to the connection between the requirements on the degree of convergence of the classical trajectory picture of the event and the purpose of the calculations. Information is obtained regarding a scale of the trajectory calculations required for physically sensible applications of the model to an interpretation of different type of experiments on the system: total ionization cross section measurements, Penning ionization electron spectra, subsequent 3D classical trajectory calculations of branching ratios of the products of the postionization collision process, and interpretation of electron ion coincidence measurements of the product branching ratios for individual vibrational levels of the nascent Penning ion.

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