Stripped oxygen, OVI, the pp' group in OV, and new aluminum lines in the extreme ultra-violet

Abstract

Lines of stripped oxygen Ovi and of Ov.—The oxygen atom holds its last electrons so tenaciously that hitherto no lines assignable to stripped oxygen have been obtained. Using aluminum electrodes and high resolution, the "lithium doublet" of stripped oxygen has been definitely located at 1031.98, 1037.69A (see Plate I) the component of shorter wave-length being, as usual with this doublet, the more intense. The use of pure Al electrodes has also enabled the pp′ group of Ov to be obtained in the fourth order, definitely resolved as a sextuplet (see Plate II) the ratio p1p2/p2p3 coming out 2.27, reasonably close to the value 2 called for by Lande's interval rule. New aluminum lines between 1250 and 500A.—Fifteen new faint lines have been discovered and all definitely placed in their proper series, belonging to Aliii and Alii. Ionization potentials of stripped atoms.—Extrapolation from the known values for stripped atoms in the first and second rows of the periodic table, gives values for the 2s term which correspond to the following ionization potentials: for Nv 97.39; for Ovi 137.35; for Fvii 184.07; and for Clvii 113.73 volts. These are probably accurate to within 0.2 volt.