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The a b s o l u t e c r o s s s e c t i o n s f o r the production of N+ and N2+ have been measured from t h e d i s s o c i a t i v e i o n i z a t i o n t h r e s h o l d t o 115 8. I n a d d i t i o n , t h e a b s o l u t e photoabsorption and p h o t o i o n i z a t i o n c r o s s s e c t i o n sare t a b u l a t e d between 1 1 4 and 796 8. The i o n i z a t i o n e f f i c i e n c i e s a r e a l s o given a t s e v e r a l d i s c r e t e wave l e n g t h s between 660 and 790 b. The production of N+ fragment ions a r e discussed i n terms o f t h e doubly e x c i t e d N2+ s t a t e s w i t h binding e n e r g i e s i n t h e range 24 t o 44 eV. P r e s e n t address, Research I n s t i t u t e

The relative photoionization cross section of atomic nitrogen for the production of singly and doubly charged ions has been measured from 44.3 to 275 A and from 520 to 852 A. The results have been made absolute by normalization to one-half of the molecular nitrogen cross section at short wavelengths. The smoothed atomic nitrogen cross sections cr can be accurately represented, at short wavelengths, by the equation 0. (Mb) =3.67X10 E ' as a function of the photon energy E 0 (eV), thereby allowing the cross sections to be extrapolated to the nitrogen K edge at 31 A.

The threshold behavior for triple photoionization of atomic oxygen and neon has been studied over a range of 10 eV in order to test the Wannier law for multiple ionization and its applicability to different states of angular momentum and spin. The cross sections are found to follow a power law in E with an exponent of 2.17 ±0.09, which is consistent with the value of 2.162 predicted by Klar and Schlecht. The energy range of validity of this law appears to be about 5.5 eV. For the case of atomic oxygen the absolute value for the constant of proportionality is found to be 5.3 x 10 ~2 4 cm 2 /eV 217 .

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