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Basic chemical processes in a CF 4/°2 plasma during etching of silicon nitride have been investigated using mass spectrometry. Samples of the discharge are extracted through a quartz capillary and the resulting variations in species abundance at a nitride/oxide interface yield information on etch reaction pathways. Mechanisms ofF and CP2 attack and SiF 4 , N 2 , NO, and CN product formation are proposed. The experimental data are suitable for application in mass spectrometric endpoint detection.

15,661 cord bloods from Jamaican infants were examined for abnormal hemoglobins using alkaline cellulose acetate electrophoresis for the initial screening, supplemented by acid agar gel electrophoresis for samples exhibiting abnormal hemoglobin bands. Of the 16 electrophoretic variants which were detected, six were fully characterized and found to be: four Hb F Port Royal (alpha2 Ggamma2 125 Glu replaced by Ala) and two Hb F Victoria Jubilee (alpha2Agamma2 80 Asp replaced by Tyr). The Hb F Port Royal samples each constituted about one eighth of the total Hb F as did seven additional samples presumed to be Hb F Port Royal. The infants with this variant exhibited no special hematological characteristics or other consistent associations. Both Hb F Victoria Jubilee samples occurred in somewhat lower proportions of the total Hb F compared with Hb F Port Royal and exhibited an apparent increase of free alpha chains in the whole hemolysate. The data available on detectable gamma chain variants suggest that a specific point mutation may occur in either a HbGgamma or a HbAgamma locus.

Doublecharge-transfer spectroscopy was used to measure the double-ionization energies of the 2-haloethanols FCH,CH,OH, CICH,CH,OH, BrCH,CH,OH and ICH,CH,OH; the values obtained were 30.1 _+ 0.5, 28.1 f 0.5, 27.6 & 0.5 and 26.9 f 0.5 eV, respectively. In addition, the energies were calculated using ab iniiio methods and the GAUSSIAN 90 program package. The measured and calculated values for FCH,CH,OH are in agreement, but for the three other molecules the calculated values are significantly lower than those measured. The discrepancies in the calculations are due mainly to the underestimation of correlation energies by the appropriate MP2 method, which becomes progressively worse with increasing number of electrons in the system.