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[No abstract submitted] / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The Stark widths of seventeen N II and ten N III spectral lines, emitted by plasmas with free electron densities of .9 ± .1 x 10¹⁷, 2.2 ± .3 x 10¹⁷ and 2.9 ± .4- x 10¹⁷ cm⁻¹³, were measured. Nine of the N II linewidths and four of the N III linewidths have not been previously measured. The plasma source was a wall stabilized discharge filled with 50% helium and 50% nitrogen. The different electron densities were produced by varying the filling pressure and charging voltage. The electron temperature was determined from the intensity ratio of several N II to N III lines. The electron densities were estimated by measuring the Stark widths of He I 5876 and 6678. The nitrogen lines were measured at different plasma conditions to check linear scaling of Stark width vs electron density on the same device. However, the large errors in both the Stark widths and the electron density measurements, about half of which came from appreciable optical depths, made it difficult to check the scaling even over the limited range of this experiment. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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The value of the dipole moment ,μ, of NH in the A³π state was found to be 1.31 ± .03 Debye. This value was determined from data on the Stark effect measured from spectrograms of the A³π- X³Σ-, 3360 Å, band taken on a 3.4 meter grating spectrograph in third order giving a resolution of about 100,000. The theory of the Stark effect in molecules was taken from papers by W. G. Penny5 and Van Vleck and Hill9 . The magnitude of the electric field was determined from the Stark splitting of the hydrogen line Hβ according to the theory given in The Theory of Atomic Spectra6 . In the near future I should be able to complete work on the c’π→a’Δ, 3240 Å, band and give the values of the dipole moments for states c and a as well. Thus it will be possible to determine how the dipole moment changes with electronic configuration. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A variation of the classical canal ray source has been developed for the study of the Stark Effect in positive ion lines. Stress was placed on the measurement of small line shifts rather than the attainment of large electric fields. To this end a sensitive shift measuring apparatus employing a linear neutral density filter to translate the line shift into a change in intensity was built. Shifts were measured to an accuracy of about .02 A° in the following lines: He I 5016 A°, 7281 A°, 6678 A°, 3889 A° and Ar I 4272 A°, 4266 A°. No shifts were detected in Ar II 4727 A° and 4806 A°. A discussion of prospective improvements to be made in the apparatus is also included. With these improvements, the apparatus should be capable of measuring shifts to an accuracy of .001 A°. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The electronic emission spectra of the OH and CH molecules in applied electric fields up to 68,000 v/cm have been observed. These spectra show Stark splittings, broadenings and field-induced, parity-forbidden lines. The electric dipole moment of the molecules has been determined for OH in the ²π electronic state and CH in both the ²π and ²∆ electronic states from Stark effects on transitions to the following levels: [formula omitted] Electric fields were determined from Stark splittings in hydrogen Balmer lines. The Stark spectra were produced in the high field region of a low pressure glow discharge. This technique is well suited for the study of short lived and chemically reactive molecules in both their ground and excited, electronic states. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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