Cross Sections of Ion—Permanent-Dipole Reactions by Mass Spectrometry

Moran, T. F.; Hamill, William H.

doi:10.1063/1.1734457

Cited by 157 publications

(33 citation statements)

References 13 publications

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“…[14][15][16][17][18] The capture cross section in many cases gives a good estimate of the momentum-transfer cross section and, therefore, these models can be easily modified to describe ion mobilities. For atomic ions in atomic gases, the ion mobility is inversely proportional to the thermally averaged momentum-transfer cross section.…”

Section: Theorymentioning

confidence: 99%

“…In the locked-dipole (ld) model 14 it is assumed that the dipole always points towards the ion, i.e., ϭ0. Capture occurs when the ion and the molecule overcome the repulsive centrifugal barrier during the collision, and the corresponding cross section is given by…”

Section: Theorymentioning

confidence: 99%

“…First, some theoretical models are introduced, which are based on existing formulations of capture processes in collisions between ions and polar molecules. [14][15][16][17][18] The models, rather than an attempt to calculate the most accurate mobility values, provide a framework to systematize and discuss the experimental results. Second, some new experimental results are presented: the mobilities of NO ϩ and H 3 O ϩ ͑H 2 O͒ 3 ions drifting in H 2 O and of NO ϩ ͑CH 3 COCH 3 ͒ n ions (nϭ2,3) drifting in CH 3 COCH 3 ͑acetone͒.…”

Section: Introductionmentioning

confidence: 99%

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The mobilities of ions and cluster ions drifting in polar gases

Gouw

Krishnamurthy

Leone

1997

The Journal of Chemical Physics

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High-resolution ion mobility measurements for silicon cluster anions and cationsThe mobility of ions drifting in polar gases is explored both theoretically and experimentally. New experimental results are presented for ͑i͒ NO ϩ ions drifting in H 2 O ͑the reduced zero-field mobility.06 cm 2 V Ϫ1 s Ϫ1 ͒, and ͑iii͒ NO ϩ ͑CH 3 COCH 3 ͒ n ions (nϭ2,3) drifting in CH 3 COCH 3 ͑K 0 (0) ϭ0.041 Ϯ0.010 cm 2 V Ϫ1 s Ϫ1 for nϭ2 and K 0 (0) ϭ0.050Ϯ0.015 cm 2 V Ϫ1 s Ϫ1 for nϭ3͒. A number of theoretical models for ion mobilities in polar gases are described. The models are compared with the available experimental data and a reasonable agreement is obtained. For larger cluster ions the measured mobilities are considerably smaller than the calculated values. Some possible reasons for the discrepancies are discussed, including momentum transfer outside the capture cross section, dipole-dipole interactions, ligand exchange, inelastic collisions, and the validity of Blanc's law.

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The mobilities of ions and cluster ions drifting in polar gases

Gouw

Krishnamurthy

Leone

1997

The Journal of Chemical Physics

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“…It seems reasonable to suppose that the removal of OH+ ions which can not be accounted for by Reaction (2) can be explained in terms of Reaction (3), Under conditions where there is low attenuation of the primary-ion beam as applies in these experiments, and if all the OH+ is removed by charge exchange to H 20+, then it is a simple matter to show that to a first approximation k(H20 +R)obs = (kH20 + R -fk oH +R) , (12) where k(H2 0 +R)obs is the observed rate coefficient for H 2 0+ removal, kH,O+R is the real coefficient for H20+ removal, k OH + R the rate coefficient for OH+ removal, and f the fraction (I OH + /1 H20 +) i which has been previously defined. For 40-eV electrons, f=0.193.…”

Section: B Reactions Of the Oh+ Ionmentioning

confidence: 88%

Ionic Collision Processes in Water Vapor

Ryan

1970

The Journal of Chemical Physics

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Some ionic collision processes in water vapor have been studied by the techniques of high-pressure singlesource mass spectrometry. Rate coefficients for reactions resulting from collisions of H20+ with H20, and of OH+ with H 2 0 have been studied as a function of primary-ion translational energy over the energy range of 0-8 eV. For purposes of calibration and comparison, the reaction leading to CHs+ production in methane gas has also been studied over the same primary-ion energy range. The rate coefficient for HsO+ production from H 2 0+ /H20 collisions was found to drop from a value of 26X 10-10 emS molecule-I. sec-l for thermal ion reactions to a value of less than half of this for ions with a maximum energy of 4 eV. HaO+ production from OH+/H 2 0 collisions was found to proceed with a rate coefficient of 20X1O-1O ems molecule-l·sec l for ions of thermal energy, but this coefficient had dropped to zero as the maximum ion energy was increased to 0.8 eV. Evidence is presented to support the contention that although HsO+ production decreases as the OH+ energy increases, the rate of removal ofOH+continues with high cross section The results indicate that in the ion energy region above 0.8 eV, OH+ is removed exclusively by charge transfer to H20.

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“…For a strongly polar molecule, the locked-dipole (ld) model [6] is used, where the dipole is assumed to always point towards the ion, giving the equation for the cross-section…”

mentioning

confidence: 99%