Ion-molecule reactions in Trihalo- and Tetrahalo-methanes

1970 ◽  
Vol 23 (5) ◽  
pp. 893 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
High Pressures ◽  
Rate Coefficients ◽  
Ion Transfer ◽  
Ion Energy ◽  
Transfer Processes ◽  
Ion Molecule Reactions ◽  
Ionic Systems ◽  
Derivatives Of

The ion-molecule reactions of eight highly halogenated derivatives of methane were studied in the gas phase using a mass spectrometer operated at high pressures. The compounds studied were CHCl3, CHCl2F, CHClF2, CHF3, CCl4, CCl2F2, CClF3, and CF4. These ionic systems were found to be less reactive than those of methane or the methyl and methylene halides. The main reactions observed were described as being halide ion transfer processes. The energy dependence of the cross sections and the rate coefficients of the reactant ions were determined.� Many rate coefficients for reactions between ions and polar molecules were found to be independent of the ion energy. Brief studies of the negative spectra at high pressures were also made.

Ion-molecule reactions of methyl fluoride and methylene chloride

1970 ◽  
Vol 23 (11) ◽  
pp. 2301 ◽  
Author(s):  
NA McAskill
Keyword(s):  
High Pressure ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
Main Product ◽  
Methylene Chloride ◽  
Reaction Cross ◽  
Rate Coefficients ◽  
Ion Molecule Reactions ◽  
Reaction Cross Sections

The ion-molecule reactions of CH3F and CH2Cl2 were examined in the gas phase using a high-pressure mass spectrometer. The ionic products of CH3F were mainly CH2F+, C2H6F+, and CH4F+. In the CH2Cl2 system the main product was CHCl2+ together with smaller amounts of CH2Cl+, CH3Cl2+, and several condensation ions. The ionic reactivity of the two compounds was compared to that of other halomethanes. Rate coefficients and reaction cross sections for many primary reactant ions were measured as a function of the ion exit energy.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

Ion-molecule reactions in methylene fluoride

1971 ◽  
Vol 24 (8) ◽  
pp. 1611 ◽  
Author(s):  
AG Harrison ◽  
NA McAskill
Keyword(s):  
Cross Sections ◽  
Ion Trap ◽  
Proton Transfer Reaction ◽  
Reaction Cross ◽  
Ion Source ◽  
Rate Coefficients ◽  
Main Reaction ◽  
Mass Spectrometers ◽  
Ion Molecule Reactions ◽  
Reaction Cross Sections

The ion-molecule reactions of CH2F2 in the gas phase were studied using two mass spectrometers, one fitted with a medium-pressure ion source and the other with an ion-trap source. The main reaction was the formation of CH2F+ from CHF2+. The molecular ion and its proton transfer reaction forming CH3F2+ were of lesser importance. The only condensation ion formed was C2H4F3+. Reaction cross sections and rate coefficients for a number of ions at exit energies of 0.2-3.3 eV were measured.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

CONCURRENT ION–MOLECULE REACTIONS IN ETHYLENE AND PROPYLENE

1963 ◽  
Vol 41 (2) ◽  
pp. 236-242 ◽  
Author(s):  
A. G. Harrison
Keyword(s):  
Field Strength ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
High Pressures ◽  
Ion Source ◽  
Molecule Reaction ◽  
Ion Molecule Reactions ◽  
Secondary Ions ◽  
The Cross

The ion–molecule reactions occurring in ethylene and in propylene at high pressures in the mass spectrometer ion source have been studied. It has been shown that two of the six secondary ions in ethylene and four of the nine secondary ions studied in propylene are products of more than one ion–molecule reaction. The cross sections for the separate reactions at 10 v/cm field strength are reported.

A gas phase study of the regioselective BH4− reduction of some 2-substituted maleic anhydrides

1988 ◽  
Vol 66 (10) ◽  
pp. 2587-2594 ◽  
Author(s):  
Hans van der Wel ◽  
Nico M. M. Nibbering ◽  
Margaret M. Kayser
Keyword(s):  
Carbon Atom ◽  
Gas Phase ◽  
Ion Cyclotron Resonance ◽  
Ion Transfer ◽  
Hydride Ion ◽  
Ion Molecule Reactions ◽  
Phase Study ◽  
Olefinic Double Bond ◽  
Gas Phase Ion ◽  
Hydride Ion Transfer

Gas phase ion/molecule reactions in a Fourier transform ion cyclotron resonance mass spectrometer have been carried out for reductions of isotopically labelled citraconic (methylmaleic), phenylmaleic, and ethoxymaleic anhydrides by BH4−. In citraconic anhydride the carbonyl group neighbouring the methyl substituent is reduced preferentially in agreement with the ab initio calculations, which show the higher LUMO coefficients at this site. Hydride ion transfer to the olefinic double bond occurs as well; however, in that case no preference for either of the carbon atoms is observed. In phenylmaleic anhydride strong indications are found for a theoretically unexpected hydride ion transfer to the phenyl ring. For ethoxymaleic anhydride experimental evidence is presented showing hydride ion transfer to the carbon atom carrying the ethoxy group, which is in agreement with the "best overlap" consideration predicting that this carbon atom bears the highest LUMO coefficient.Most of the hydride transfers from BH4− to the molecules studied seem, therefore, to take place under orbital control rather than under control of long-range ion-induced dipole interactions between reactants.

Reaction of •OH with CHCl=CH-CHF2 and its atmospheric implication for future environmental-friendly refrigerant

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Olivier Holtomo ◽  
Lydia Rhyman ◽  
Mama Nsangou ◽  
Ponnadurai Ramasami ◽  
Ousmanou Motapon
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
Radiative Forcing ◽  
Rate Coefficient ◽  
Computational Method ◽  
Rate Coefficients ◽  
Ir Absorption ◽  
Geometrical Structures ◽  
Atmospheric Lifetime ◽  
Environmental Friendly

Abstract In order to understand the atmospheric implication of the chlorinated hydrofluoroolefin (HFO), the geometrical structures and the IR absorption cross sections of the stereoisomers 1-chloro-3,3-difluoropropene were studied using the B3LYP/6-31G(3df) and M06-2X/6-31G(3df) methods in the gas phase. The cis-trans isomerization was assessed using the M06-2X/6-311++G(3df,p)//6-31+G(3df,p) method. The latter method was also employed for thermochemistry and the rate coefficients of the reactions of •OH with the cis- and trans-isomers in the temperature ranging from 200 to 400 K. The computational method CCSD/cc-pVTZ//M06-2X/6-31+G(3df,p) was used to benchmark the rate coefficients. It turns out that, the trans-isomer is more stable than cis-isomer and the trans- to cis-isomerization is thermodynamically unfavorable. The rate coefficient follows the Gaussian law with respect to the inverse of temperature. At the global temperature of stratosphere, the calculated rate coefficients served to estimate the atmospheric lifetime along with the photochemical ozone creation potential (POCP). This yielded lifetimes of 4.31 and 7.31 days and POCPs of 3.80 and 2.23 for the cis- and trans-isomer, respectively. The radiative forcing efficiencies gave 0.0082 and 0.0152 W m−2 ppb−1 for the cis- and trans-isomer, respectively. The global warming potential approached zero for both stereoisomers at 20, 100, and 500 years time horizons.

Neutralization of Ion Beams for Reduction of Charging Damage in Plasma Etching

2005 ◽  
Vol 494 ◽  
pp. 297-302 ◽  
Author(s):  
Aleksandra Nina ◽  
M. Radmilović-Radjenović ◽  
Z.Lj. Petrović
Keyword(s):  
Monte Carlo ◽  
Gas Phase ◽  
Plasma Etching ◽  
Cross Sections ◽  
Ion Beams ◽  
Monte Carlo Code ◽  
Motion Simulation ◽  
Ion Energy ◽  
Ion Motion ◽  
Neutral Beams

Neutral beams were proposed for plasma etching in order to reduce damage due to charging. We analyzed the efficiency of neutralization in a system proposed recently where a beam of ions was neutralized in the gas phase and in a set of narrow tubes. We studied surface neutralization as well as collisions of ions in the gas. In the case of collisions of ions with aperture walls, efficiency of neutralization was assumed to be 100%. We also investigated the influence of various parameters such as aperture length, tube diameter and initial ion energy on the efficiency of neutralization using a Monte Carlo code for ion motion simulation. In our calculations we used a well-established set of cross sections for argon.

Energy dependence of ion-molecule reactions. II. Methyl chloride

1969 ◽  
Vol 22 (11) ◽  
pp. 2275 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Energy Range ◽  
Gas Phase ◽  
Energy Dependence ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Methyl Chloride ◽  
Negative Ion ◽  
Polar Molecules ◽  
Ion Energy ◽  
Ion Molecule Reactions

The ion-molecule reactions of ions in methyl chloride were studied in the gas phase at source pressures of up to 120 μ in a mass spectrometer using ions having exit energies which ranged from 0.2 to 2.0 eV. The ions produced by secondary processes included CH4Cl+, CH2Cl+, and C2H6Cl+. The rate constant for the reaction of CH3Cl+ was found to be independent of the ion energy in the energy range studied. A theoretical rate constant which is independent of the ion energy was also derived for reactions between ions and polar molecules. Negative ion spectra were briefly examined.

Ion-molecule reactions in uranium hexafluoride

1975 ◽  
Vol 28 (9) ◽  
pp. 1879 ◽  
Author(s):  
NA McAskill
Keyword(s):  
Kinetic Energy ◽  
Gas Phase ◽  
Mass Spectrometer ◽  
Uranium Hexafluoride ◽  
Ion Source ◽  
Rate Coefficients ◽  
Medium Pressure ◽  
Ion Molecule Reactions ◽  
Ion Kinetic Energy

The ion-molecule reactions of UF6 in the gas phase were studied in a mass spectrometer fitted with a medium-pressure ion source. The main reactions were the collision-stabilized formation of U2F11+ from UF5+, U2F10+ from UF4+ and U3F16+ from U2F10+. Rate coefficients for the reactions of UF5+ and UF4+ with UF6 and the distribution of their products were found to depend upon the ion kinetic energy.

Sign in / Sign up

Export Citation Format

Share Document