Description and analysis of the second spectrum of chromium, Cr-II

Abstract

Th.e analy~i s of S;~. II presented in this pa p,er is based on new wavelength mea sure men ts and eS~lma t~d 1I1~en sltl es, a nd on n ew obse rvation s of the Zee man effect. Of a pproximately 2,100 l1l1 es llsted 111 t he t ables, 89 per cen t ha ve been classified as combinat ions of t he leve ls of 4. 8 even terms with levels of 51 odd terms. The e ven terms arise from t he electron co nfig urat lOn s 3d 5, 3d' 48, and 3d 3 48 2 , t he odd terms from t he confi gura tion 3d' 4p. No odd te rm s from t he configuration 3d 3 48 4p have been established . High even terms from t he excited configurat ions 3d' 4d and 3d' 58 have been found tha t form R ydberg se ries wi t h terms from t he low even config ura tions. From t he m an ionizat ion potent ial of 16.49 electron volts ha s been de~iv~d for t he ~o rk required t o conver t a singly ionized Cr a to m in the a 6S2)l state to a doubly 1Ol1Jzed a to m 111 t he a 5D O sta te. The term s of t he 3d 3 48 2 config uration li e high in t he energy scale, and only a few relatively fain t combinations betwee n t hem a nd t he odd term s have been found.

COMPREHENSIVE OBSERVATIONS OF THE ULTRAVIOLET SPECTRUM AND IMPROVED ENERGY LEVELS FOR SINGLY IONIZED CHROMIUM (Cr II)

“…More than 1000 of these lines are in the vacuum ultraviolet region below the 1786 Å limit of observation of Kiess (1951). At longer wavelengths, the weakest lines reported by Kiess are not observed, but many new lines have been measured and classified.…”

“…Using the FTS data only, an initial set of line identifications was made by comparison to the line list of Kiess (1951) and predicted wavelengths based on Johansson's preliminary level values (Sugar & Corliss 1985). These lines were used to make an initial optimization of the energy levels using the computer program ELCALC.…”

“…The only comprehensive analysis of the Cr ii spectrum in the literature is the six-decade-old work of Kiess (1951). He reported observations of spectra excited in direct current arcs and condensed sparks between chromium electrodes.…”

A spectroscopic atlas of Deneb (A2 Iae) $\lambda\lambda$3826–5212

“…Cr II (Kiess 1951): Almost all lines with intensities 4 and greater are found. Some intensity 2 lines are found.…”

IV. Reports of Meetings of Commissions Comptes Rendus des Seances des Commissions

“…(4) There is an urgent need of Cr II data in the short wavelength region of IUE. In the previous analysis of Cr II (Kiess 1951) The overlapping of these three low configurations of the same parity is considerable through the whole iso-ionic sequence of singly ionized iron group elements. This is illustrated in Figure 1 where the relative positions of the configurations are represented by their lowest LS term.…”