Alois Langer

Ionization and Dissociation by Electron Impact; Methylene, Methyl, and Methane

The appearance potentials of C+, CH+, and CH2+ in the mass spectra of methylene, methyl, and methane are found to be mutually consistent and when combined with the spectroscopic value of the ionization potential of the carbon atom (11.26 ev) lead to 15.5±0.5 ev/molecule for the heat of atomization of methane. This value (15.5) when further combined with the heat of formation of methane (—0.78 ev/molecule) and the dissociation energy of H2 (4.48 ev/molecule) yields 5.76 ev/atmos or 133 kcal/mole for the heat of sublimation of graphite.The set of appearance potentials confirmed the spectroscopic value for the heat of dissociation of CH+ (3.6 ev/molecule) and yield the following additional energetic quantities: D(CH2–H) = 3.75±0.3 ev/molecule, D(CH–H) = 3.99±0.3 ev/molecule, D(CH3+–H) = 1.34±0.1 ev/molecule, D(CH2+–H) = 5.54±0.2 ev/molecule, and D(CH+–H) = 3.37±0.2 ev/molecule. Earlier determinations of Iz(CH4), Iz(CH3) and D(CH3–H) are confirmed (within the experimental error) and the ionization potential o...

Exchange of Radioactive Silver and Bromide with Silver Bromide Suspensions

The exchange of radioactive silver and bromide ions with aqueous silver bromide suspensions was studied. It was observed that both constituents of the silver bromide lattice exchange with the ions in solution. A strong dependence of the exchange rate on the amount of surface of the precipitates used, for both the silver and the bromide was observed. A pronounced difference was found in the exchange rate for bromide if dye molecules were adsorbed on the precipitate prior to the exchange experiment. The rate for silver was not affected by the presence of the adsorbed dye molecules. A discussion of these results is included.

Exchange of Radioactive Silver with Silver Chloride Suspensions

From exchange experiments on radioactive silver in solution with silver chloride in suspension, it can be shown that the silver ions in solution are constantly exchanging with the silver ions in the precipitate. This exchange is not limited to the surface of the crystals, but, probably by means of self‐diffusion, is propagated into the precipitate. A steady radioactive state obtains when a homogeneous distribution of the radioactive silver throughout the whole system is reached. The time necessary to obtain a given fraction of complete exchange for a given amount of precipitate depends strongly on the area of the crystal surface.

Appearance Potentials of Some Metastable Transition Ions Found in Hydrocarbon Mass Spectra

The appearance potentials of some metastable transition peaks in normal butane, isobutane, the butenes, and 1,3‐butadiene have been studied along with the parent ions in each metastable transition. A comparison shows that in most cases studied, an additional energy of about 2 ev is required for the formation of the metastable state. However, in the case of normal butane, two transitions were studied in which no additional energy was required within an experimental error of 0.3 ev. Evidence is presented which indicates that in some cases the appearance potentials of ions in hydrocarbon spectra are affected by these metastable ion contributions. This effect may account for some of the unexplained discrepancies found in published data on hydrocarbon gases. Check values of some ions in methane, ethane, and propane were taken to determine the performance of the instrument. A comparison of these results is made with previously published data.

Gas Circulating Apparatus Containing a Magnetic Balance

A gas circulating system is described in which a sample undergoing thermal decomposition can be weighed continuously by means of a magnetic balance having a sensitivity of the order of 0.1 mg. Changes of composition in the gases contained in the system are determined by withdrawing samples directly into a mass spectrometer for analysis. Accurate quantitative measurements of the uptake and evolution of gases during the degradation process are thus obtained, providing an insight into the reactions that occur.This simple system should prove useful in many other fields of investigation.