Ion–molecule reactions in gaseous methyl amine

1967 ◽  
Vol 45 (24) ◽  
pp. 3119-3128 ◽  
Author(s):  
E. G. Jones ◽  
A. G. Harrison
Keyword(s):  
Rate Coefficients ◽  
Ion Energy ◽  
Methyl Amine ◽  
Ion Molecule Reactions ◽  
Ion Energies ◽  
Theoretical Predictions

The ion–molecule reactions in gaseous methyl amine have been studied. The following reactions have been identified and their rate coefficients (all in cm3 molecule−1 s−1 units) determined for ions of 3.4 eV ion exit energy. [Formula: see text]Reactions [a] and [c] were also studied at thermal ion energies and little variation of the rate coefficients with ion energy was found in contrast with theoretical predictions.

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 IN METHYL ALCOHOL AND METHYL-d3 ALCOHOL

1966 ◽  
Vol 44 (14) ◽  
pp. 1655-1661 ◽  
Author(s):  
J. C. J. Thynne ◽  
F. K. Amenu-Kpodo ◽  
A. G. Harrison
Keyword(s):  
Methyl Alcohol ◽  
Rate Constants ◽  
Hydrogen Transfer ◽  
Rate Coefficients ◽  
Collision Complex ◽  
Ion Molecule Reactions ◽  
Ion Energies ◽  
Hydroxyl Hydrogen

The rate constants for the hydrogen-transfer ion-molecule reactions[Formula: see text]have been measured at thermal ion energies and found to be 12 × 10−10 cm3 molecule−1 s−1 and 8.0 × 10−10 cm3 molecule−1 s−1 respectively. The rate coefficients at higher ion energies (3.7 eV ion exit energy) show little change from these values. Reactions [a] and [b] have also been studied using CD3OH and it is found that in reaction [a] the hydroxyl hydrogen is transferred 2.5 times more readily at low ion energies and 1.8 times more readily at high ion energies than a methyl hydrogen. This rather small specificity would appear to preclude formation of a "locked-in" collision complex even at low ion energies.

Ion–Molecule Reactions in Methyl Fluoride and Methyl Chloride

1971 ◽  
Vol 49 (13) ◽  
pp. 2217-2222 ◽  
Author(s):  
A. A. Herod ◽  
A. G. Harrison ◽  
N. A. McAskill
Keyword(s):  
Kinetic Energy ◽  
Methyl Chloride ◽  
Molecular Ions ◽  
Rate Coefficients ◽  
Minor Importance ◽  
Methyl Fluoride ◽  
Ion Molecule Reactions ◽  
Fragment Ions ◽  
Ion Energies ◽  
Ion Kinetic Energy

The reactions of the molecular ion have been studied as a function of the ion kinetic energy for methyl fluoride and methyl chloride. The following reactions are observed[Formula: see text]For methyl fluoride (X = F) reactions c and d have kinetic energy thresholds and become significant at high ion energies. For CH3Cl (X = Cl) reaction a is not observed and reactions c and d are of only minor importance at high ion energies. Rate coefficients for the molecular ions and a number of fragment ions as well as rate coefficients for further reaction of CH4X+ are reported.

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>

Physical and Chemical Sputtering at Very Low Ion Energy: the Importance of the Sputtering Threshold

1988 ◽  
Vol 129 ◽  
Author(s):  
Christoph Steinbruchel
Keyword(s):  
Threshold Energy ◽  
Surface Binding ◽  
Ion Energy ◽  
Chemical Sputtering ◽  
Surface Binding Energy ◽  
Physical Sputtering ◽  
Chemical Etch ◽  
Ion Energies ◽  
The Difference ◽  
Physical And Chemical

ABSTRACTA variety of data for physical etching (i.e. sputtering) and for ion-enhanced chemical etching of Si and SiO2 is analyzed in the very-low-ion-energy regime. Bombardment by inert ions alone, by reactive ions, and by inert ions in the presence of reactiveneutrals is considered. In all cases the etch yield follows a square root dependence on the ion energy all the way down to the threshold energy for etching. At the same time, the threshold energy has a non-negligible effect on the etch yield even at intermediate ion energies. The difference between physical and ion-enhanced chemical etch yields can be accounted for by a reduction in the average surface binding energy of the etch products and a corresponding reduction in the threshold energy for etching. These results suggest that, in general, the selectivity for ion-enhanced etch processes relative to physical sputtering can be increased significantly at low ion energy.

scholarly journals The Formation of Interstellar Molecules via Radiative Association Reactions

1980 ◽  
Vol 87 ◽  
pp. 323-324
Author(s):  
David Smith ◽  
Nigel G. Adams
Keyword(s):  
Rate Coefficients ◽  
Rate Data ◽  
Association Rate ◽  
Interstellar Molecules ◽  
Ion Molecule Reactions ◽  
Radiative Association ◽  
Temperature Dependences ◽  
Association Reaction

The radiative association rate coefficients and their temperature dependences have been estimated for several likely interstellar ion-molecule reactions from laboratory collisional association rate data. They include the CH3+ + H2 and CH3+ + H2O reactions, which we suggest lead to CH4 and CH3OH respectively, and the critical association reaction C+ + H2.

Termolecular ion–molecule reactions involving C3H5+

1970 ◽  
Vol 48 (22) ◽  
pp. 3549-3553 ◽  
Author(s):  
A. G. Harrison ◽  
A. A. Herod
Keyword(s):  
Kinetic Energy ◽  
Molecular Size ◽  
Order Rate Constant ◽  
Second Order ◽  
Rate Coefficients ◽  
Third Order ◽  
Order Rate ◽  
Ion Molecule Reactions ◽  
Similar Dependence ◽  
Ion Kinetic Energy

The reaction of C3H5+ with C2D4 to produce C5H5D4+ is shown to be second order in C2D4. The rate coefficients are in the range 10−24 to 10−25 cm6 molecule−2 s−1 but decrease markedly with increasing ion kinetic energy. This decrease reflects the effect of the ion kinetic energy on the lifetime of the initial collision complex. Small differences in rate coefficients are observed depending on the source of the C3H5+ ion but these are insufficient to distinguish between possibly different ionic structures. The reaction of C3H5+ with C2H3F forms C5H7+ in a reaction second order in C2H3F. The rate coefficients are also in the range 10−24 to 10−25 cm6 molecule−1 s−1 and show a similar dependence on ion kinetic energy. These high third order rate constants are compared with data for other termolecular reactions and are shown to be consistent with the effect of molecular size on the third order rate constant.

Dry Etch Damage in GaAs P-N Junctions

1991 ◽  
Vol 240 ◽  
Author(s):  
S. J. Pearton ◽  
F. Ren ◽  
C. R. Abernathy ◽  
T. R. Fullowan ◽  
J. R. Lothian
Keyword(s):  
Plasma Etching ◽  
Ion Bombardment ◽  
Plasma Exposure ◽  
Base Resistance ◽  
Ion Energy ◽  
Ion Energies ◽  
A Minor ◽  
P Type ◽  
Dry Etch ◽  
Very High

ABSTRACTGaAs p-n junction mesa-diode structures were fabricated so that both n- and p-type layers could be simultaneously exposed to either O2 or H2 discharges. This simulates the ion bombardment during plasma etching with either CCl2F2/O2 or CH4/H2 mixtures. The samples were exposed to 1 mTorr discharges for period of 1–20 min with DC biases of -25 to -400V on the cathode. For O2 ion bombardment, the collector resistance showed only minor (≤10%) increases for biases up to -200 V and more rapid increases thereafter. In our structure, this indicates that bombardment-induced point defects penetrate at least 500 Å of GaAs for ion energies of ≥200eV. The base resistance displayed only a minor increase (∼10%) over the pre-exposure value even for O+ ion energies of 375 eV, due to the very high doping (1020 cm−3 ) in the base. More significant increases in both collector and base resistances were observed for hydrogen ion bombardment due to hydrogen passivation effects. We will give details of this behaviour as a function of ion energy, plasma exposure time and post-treatment annealing temperature.

Electron Cyclotron Resonance Plasma Processing of GaAs-AlGaAs Hemt Structures

1991 ◽  
Vol 240 ◽  
Author(s):  
S. J. Pearton ◽  
F. Ren ◽  
J. R. Lothian ◽  
T. R. Fullowan ◽  
R. F. Kopf ◽  
...  
Keyword(s):  
Plasma Etching ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Complete Removal ◽  
Pattern Transfer ◽  
Hydrogen Passivation ◽  
Ion Energy ◽  
Ion Energies ◽  
Resonance Plasma ◽  
Or Gate

ABSTRACTThe damage introduced into GaAs/AlGaAs HEMT structures during pattern transfer (O2 plasma etching of the PMGI layer in a trilevel resist mask) or gate mesa etching (CCl2F2/O2 or CH4/H2/Ar etching of GaAs selectively to AlGaAs) has been studied. For etching of the PMGI, the threshold O+ ion energy for damage introduction into the AlGaAs donor layer is ∼200 eV. This energy is a function of the PMGI over-etch time. The use of ECR-RF O2 discharges enhances the PMGI etch rate without creating additional damage to the device. Gate mesa etching produces measurable damage in the underlying AlGaAs at DC negative biases of 125–150V. Substantial hydrogen passivation of the Si dopants in the AlGaAs occurs with the CH4 /H2 /Ar mixture. Recovery of the initial carrier concentration in the damaged HEMT occurs at ∼400°C, provided the maximum ion energies were dept to ≤400 eV. Complete removal of residual AIF3 on the CCl2F2/O2 exposed AlGaAs was obtained after H2O and NH4 OH:H2O rinsing while chlorides were removed by H2O alone.

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