Itiro Omura

Mass Spectrometric Studies of Photoionization. IV. Acetylene and Propyne

Photoionization efficiency curves for the parent ions of C 2 H 2 and C 3 H 4 have been measured with a photon bandwidth of 1.3A. For the C 2 H 2 + ion, the minimum onset for ionization of C 2 H 2 occured at 1088 A (11.395±0.015 eV). Vibrational structure and autoionization were observed above the threshold region. For the C 3 H 4 + ion, the minimum onset occured at 1198 A (10.349±0.015 eV), and the second ionization for the C 3 H 4 + ion was observed at 1103 A (11.24 eV). Above the threshold there were observed several vibrational structure and autoionization.

On the Measurement of Isotope Abundance of Lithium with Mass Spectrometer

The values of the isotope abundance ratio Li/sup 7/Li/sup 6/ obtained were 12.48 plus or minus 0.05 and 13.69 plus or minus 0.05 for two samples of lithium chloride. (W.D.M.)

Mass Spectrometric Studies of Photoionization. V. Methanol and Methanol-d1

Photoionization efficiency curves have been determined for parent and fragment ions of methanol and methanol- d 1 in the photon energy range from 1150 A to 950 A. Vibrational and autoionization levels of the parent ions were observed in a region near the threshold of the photoionization efficiency curves. The vibrational structure observed in this work was analyzed using both the isotope effect and infrared spectroscopic data. Above the threshold of photoionization were observed two vibrational structures; the stretching and the twisting vibrations.

Characteristics of Microwave Plasma Observed by Spectroscopic and Mass Spectrometric Methods

The plasma light source operated in the standing wave mode are analyzed experimentally by using two methods. One is the spectroscopic method, and the other is the mass spectrometric method. Using the former method we can identify the several lines in the vacuum ultraviolet regions. There are the resonance lines and the emission lines for the carrier gas. For example, the emission lines of Ar V at 524 A, Ar VII at 462 A and He II at 304 A are generated from the argon and the helium plasma operated in the standing wave mode. On the other hand, the resonance lines of Ar I at 1048 A and He I at 584 A are generated from the plasma without the standing wave mode. Using the latter method, we can observe the mass spectrum of organic compounds irradiated with the resonance line and the emission line. In order to use as a light source of the mass spectrometer, the optimum operated conditions are determined as a function of the carrier gas pressure.

Charge Transfer in Ion-Molecule Interactions Studied by the Resonance Line of Helium

An intrinsic chemical reaction between CH4+ and C3H6 is found to be more active than the simple charge transfer reactions between rare gases and propylene. Charge transfer reactions are observed with he pressure range of 1-8×10-3 mmHg in the ionization chamber. There are the charge transfer dissociative reactions between Ar+, Kr+ or CH4+ and C3H6, and the probability of the charge transfer can be shown with the difference of the ionization potential between the added gas and the propylene. Dissociative reaction between He* and C3H6 can not be detected in this pressure range, but He+ ion is found to have the character as a reactant particle to C3H6.

Multiple Dispersion Mass Spectrometer with Ion Mirror

Ion mirrors are introduced to realize multiple dispersion in a single magnetic field of a mass spectrometer. An ion source, two ion mirrors, and an ion collector are suitably placed around a magnetic field. The ion mirrors can also be used as ion collectors. If the polarity of the accelerating voltage is reversed, negative ions can be analyzed. (C.E.S.)