Inosuke Koyano

Ion—Molecule Reactions by a Photoionization Mass Spectrometer. I. Propylene and 1,3-Butadiene

Ion—molecule reactions in propylene and 1,3-butadiene have been studied using a mass spectrometer which utilizes photoionization as an ion source instead of electron impact. The light source used was a low-pressure hydrogen-discharge lamp with a LiF window (substantially Lyman alpha, 1216 A). It has been shown that this method has two major advantages in the study of ion—molecule reactions compared with the electron-impact method; one is the lack of unimolecular fragmentation of the parent ion and the other the absence of hot filament, which enables one to get high pressure without suffering pyrolysis.Five reactions of C3H6+ with C3H6 and eight reactions of C4H6+ with C4H6 have been identified and the cross sections determined for these reactions. In propylene, the reaction leading to the formation of C3H7+ was found to be of the largest cross section and, although cross section was small, the reaction forming C3H3+ was found as a new reaction. It was shown that C3H6+ could not be the precursor of seconda...

Ion—Molecule Reactions by a Photoionization Mass Spectrometer. II. Butene−1, Butene−2, and Isobutylene

Ion—molecule reactions of the parent ions of butene−1, butene−2 (cis and trans), and isobutylene with their corresponding neutral molecules have been studied by a photoionization mass spectrometer. Seven reactions of butene−1 parent ions, three of butene−2, and three of isobutylene have been identified and their cross sections determined. Parent‐plus‐one and parent‐minus‐one reactions occurred more or less in all olefins studied, among which C4H9+ formation in isobutylene had a much larger cross section than others. Butene−2 parent ions were highly unreactive compared with the other two olefin ions, and their cis and trans isomers showed the same reactions with exactly the same cross sections.

The effect of vibrational and translational energies of ionic reactant on the reaction NO++iso‐C4H10→HNO+C4H+9

The effect of vibrational energy of the ionic reactant on the rate of the reaction NO++iso‐C4H10→HNO+C4H+9 has been examined by directly determining the relative reaction cross sections for the individual vibrational states from v=0 to 4. The reactant ions were produced by photoionization at suitable wavelengths and the relative abundances of the ions in various vibrational states were determined at each wavelength by photoelectron spectrometry. The translational energy dependence of the individual cross sections has also been studied by changing the repeller voltage in the ionization chamber. The cross section slightly decreased with increasing vibrational energy at lower relative kinetic energies, but it was almost constant within the experimental error at higher relative kinetic energies. The result has been explained in terms of the two‐mechanism model, viz., complex formation predominating at lower relative kinetic energies and stripping predominating at higher relative kinetic energies. Photoelectro...

Lyman Alpha Lamps and Reaction of Deuterium Atoms in the 2P State with Molecular Nitrogen

Characteristics of hydrogen‐ and deuterium‐Lyman alpha, emitted from their respective electrodic discharge lamps, were investigated, and the optimum conditions were determined for the production of resonance lines of sufficient intensity and sharpness for producing H(2P) or D(2P) atoms by irradiation of the ground‐state atoms. Reactions between H(2P) or D(2P) atoms and molecular nitrogen were also studied by irradiating the mixtures H+N2 or D+N2 with H Lyman alpha or D Lyman alpha, and the following results were obtained: H+N2+H Lyman alpha→NH3,H+N2+D Lyman alpha→no product,D+N2+H Lyman alpha→no product,D+N2+D Lyman alpha→ND3. Moreover, the relation between the amount of the product and the rate of 2P atom formation was examined, and it was found that the former is strongly affected by the latter.

Effect of structure of reactants on the ion-molecule reactions C3H4+ + C3H4

Abstract Ion-molecule reactions of C3H4+ with C3H4 in cyclopropene/propyne and allene/ propyne mixtures as well as in pure cyclopropene and allene are studied by a photoionization mass spectrometer. Product distributions of C3H3+, C6H5+, and C6H7+ differ in intensity from one system to another. Such differences are attributed to the nature of reactants and intermediates. The structure of the neutral molecule is especially significant in determining the product distribution.

Ion‐molecule reactions by a photoionization mass spectrometer. IV. C5‐unsaturated hydrocarbons

The reactions of parent ions of five pentene isomers and cyclopentene with their corresponding neutral molecules have been studied at 1.7 eV ion exit energy using a photoionization mass spectrometer in the pressure range between 1 and 10 mtorr. Pentene‐1 was the most reactive system and 3‐methylbutene‐1 and 2‐methylbutene‐2 were much less reactive than others. C5H11+ formation in 2‐methylbutene‐1 had an exceptionally large cross section and this made the system much more reactive than other branched chain pentenes. Dimeric ions (C10 ions) were detected in all of the systems and no C9 ions were observed in any of the systems. Distribution of C6, C7, and C8 product ions in pentene isomers can be explained by the mechanism proposed by Henis except in the case of 2‐methylbutene‐2 where some rearrangements in the intermediate are necessary to explain the product distribution. Parent‐minus‐two reactions occurred in normal chain pentenes but did not in branched chain isomers. Parent‐minus‐one and parent‐plus‐one...

Detection of long-lived excited states of N2 by photoionization

Abstract N2+ ions were found to be produced when nitrogen discharge flow gas was irradiated at four wavelengths, 121.6, 184.9, 253.7, and 632.8 nm, in the ionization chamber of a mass spectrometer. Charged particles produced in the discharge were eliminated before irradiation. The wavelengths used are longer than the ionization threshold of the ground-state nitrogen and the observed ions are attributed to the photoionization of long-lived excited states formed downstream to the discharge. The amount of photoions produced decreased rapidly with increasing wavelength. Some excited states of N2 which are likely to be relevant to the photoionization have been discussed.

Ion–Molecule Reactions by a Photoionization Mass Spectrometer. III. C3H6+n‐C4D10 and Cyclo‐C3H6+n‐C4D10 Mixtures

Ion–molecule reactions of the parent ions of propylene and cyclopropane (C3H6+ and cyclo‐C3H6+, respectively), with deuterated n‐butane (n‐C4D10) have been studied by a photoionization mass spectrometer. Ionizing radiation was Lyman alpha (1216 A) which produced only one primary ionic species (C3H6+ or cyclo‐C3H6+) in the mixture of C3H6 and n‐C4D10 or of cyclo‐C3H6 and n‐C4D10. It has been found that, besides the two reactions, D− and D2− transfer, deuterium atom abstraction by C3H6+ (or D atom transfer) takes place in each system. Reaction cross sections for all of these reactions have been determined at a field strength of 4.0 V/cm. These values in angstroms2 unit are: D− transfer 13, D2− transfer 7.1, D transfer 4.8 (C3H6+n‐C4D10 system), D− transfer 30, D2− transfer 2.0, D transfer 8.1 (cyclo‐C3H6+n‐C4D10 system).