RESONANCES IN PHOTO-IONIZATION CONTINUUM OF AR I (20-150EV)

The absorption spectrum of argon in the region 600-80 (20-150 eV) has been studied photographically and photoelectrically, using synchrotron light as a background source and a resolution of 0.06. Many resonances have been observed in the photo-ionization continuum, which are caused by electronic excitation to auto-ionizing states of Ar i. In the region between 27 and 40 eV the observed structure is due to two types of electronic excitation: (i) the excitation of a single 3s electron, resulting in the configuration 3s 3p6 np and (ii) the excitation of two of the outer 3p electrons simultaneously, resulting in configurations of the type 3s23p4 nl n′l′. Between 44 and 59 eV, weak structures have been observed in the absorption continuum because of the simultaneous excitation of a 3s and a 3p electron, resulting in configurations of the type 3s 3p5 nl n′l′. All of the observed resonances have been tabulated, and a partial classification has been given. The profiles of the resonances involving states 3s 3p6 np P11, for n=4,5, and 6, and the two-electron excitation states 3s23p4(P3)4s(P322)4p and 3s23p4(P3)3d(P322)4p, have been studied quantitatively. The values of q, ρ2, and Γ have been determined for each of these resonances, and the continuum cross section has been measured between 24 and 36 eV. © 1969 The American Physical Society.