Glow discharges, determination

It has been experimentally determined that a number of sources of radicals, including some generated by pyrolysis, may be used for this technique. However, the low-temperature glow-discharge is a convenient source of radicals for synthetic work. 

F. L. King, J. Teng, and R. E. Steiner. Glow Discharge Mass Spectrometry Trace Element Determinations in Solid Samples. J. Mass Spectrom., 30(1995) 1061-1075. 

Mass spectrometer studies of oxidant additions to fluoro- and chlorocarbon gases have demonstrated that the relative reactivity of atoms with unsaturate species in a glow discharge follows the sequence F -- O > Cl > Br (41), Of course, the most reactive species present will preferentially undergo saturation reactions that reduce polymer formation and that may increase halogen atom concentration. Ultimately, determination of the relative reactivity of the plasma species allows prediction of the primary atomic etchants in a plasma of specific composition. 

H. A. Weakliem, Diagnostics of Silane Glow Discharges Using Probes and Mass Spectroscopy L. Gluttman, Relation between the Atomic and the Electronic Structures A. Chenevas-Paute, Experiment Determination of Structure 5. Minomura, Pressure Effects on the Local Atomic Structure D. Adler, Defects and Density of Localized States... 

The experiments were carried out on high purity aluminium from different producers (Table I) and Al-Ga alloys. The impurity concentration in the used materials was determined by glow discharge mass-spectrometry. The total impurity content in pure aluminium (0.4 - 7.7 ppm) was defined as the sum of the concentration of all found elements.The residual resistivity ratio RRR=p(273K)/p(4.2K) of the materials was measuredby the method prescribed by the U.S. National Bureau of Standards. 

The original C.P.D. determinations of Oatley (44) were made with Ha and Oa on a Pt anode. The gases were ionized, and the work function of the anode increased by 1.2 v. with Oa and decreased by 1.15 v. with Ha. Similarly, Weissler and Wilson (46) obtained C.P.D. values of —1.2 v. and up to —1.4 V. for the adsorption of Oa on W and Ag films which were evaporated on to the inside of a cylindrical Ta anode. Adsorption was promoted by means of a glow discharge. Less reliable positive S.P. values were obtained for the adsorption of Ha and Na. The results were not always reproducible, and it is possible that the anode was a source of contamination. 

The glow discharge ion source is simple yet versatile, providing information for emission and mass spectrometric methods.92 A glow discharge ion source combined with a mass spectrometer has supplanted the spark ion source over many decades as the predominant ionization technique of mass spectrometry for determining trace and ultratrace element concentrations in various types of... 

---