In 1894, two short se ries of t hreefold spectra l tcrms wcrc d iscov cred in t he a re spcctru.'n of manganese, and in 1922 other regula ri t ies invo lving fi vcfold and s ixfold te rms were d iSco vered by Catala n who coined t he word " mul t iple t" fo r t he group of related li nes res ult lll g from combinations of such complex terms. M ult iplet a na lyses of co mplex spectra promptly led t o t he prese nt formal quan t um inte rpretation of a ll suc h ph enomena, b ut co mpa ra ble progress in the analys is of t he Mnl spectrum was ha nd lcappcd by t he p a ucity of experimental data.. . . r.New observations of about 2500 wavelengt hs andl11 tc nSlt lcs plu s .440 Zeema n p atterns made a vailable in 1948-49 have now been co mpl ctely ex pl o ltcd to dcn ve ad di tIO nal ato mi c energy levels a nd t hcreby expl a in m ore of t he o bser ve d M n I Ii ncs. Th e res ul t IS t hat a total of 42 even t erms wit h 125 Icvcls a nd 60 g-valucs havc now bce n deS ig nated a nd a ll ocated to elec tron co nfi o-urations a nd 94 odd tc rms wit h 266 Icvels, 164 g-va lues, plu s 13 mi scell a neo us levels. Thes~ te rms a'rc di st ri b ut cd a mong four mul t ipli cities (dou blets, q ua rt? ts, sextet s, oc tets) , a nd tra nsit ions bet ween eve n '); nd odd te rms acco u nt for more t ha n 2030 bnes r a ngll1 g in wavelcngt h fr om 1785 X. to 17608 A.

Wa v ele ngt hs a nd estimated in te nsit ies o f a pprox imately 2, 000 s pectr al lines emit ted by sin gly ionized rhenium ato ms were avail a bl e for t his an alys is. Obser ved Zee m an p atte rns for 22 0 R e II lin es facili tated findin g a nd i nterpretin g t he first energy levels. The a nalys is co n t in ued un t il 49 low-even, a nd 85 high-odd levels were found . Tra nsit ion s b etwee n t hese g ro ups of levels acco un t for 1,01 4 R e II lin es in cluding a bo u t 70 percent of t he total o bser ved i nte ns ity. The gr o und state of R e+ is d esc ribed by th e sp ectral ter m 5d5(a6S)6s a7S3.

With t he aid of new data on wavelengths, intensities, and t he Zeem an effect, t he structural analysis of the first spectrum of rhenium (Re I) has been extended to include 2,764 lines that are explained as transitions among 282 atomic en ergy levels. This analysis accounts for 90 percent of the total observed intensity, alt hough only 64 p ercent of t he t otal number of lines has been classified. From the Zeeman effect, magnetic splittin g fac t ors h ave been derived for 75 percent of the levels, and nearly 40 percent of t hese have been grouped into designated spectral terms ascribed to speci fic configurations of electrons. The normal state of neutral R e atoms is 5d 5 68 2 682», and t he ionization limit is approximately 63530 kaysers or 7.87 electron volts.

No abstract

Spectrograms of manganese made a t the Massachusetts In stitute of Technology with fi elds in excess of 84,000 oersteds show many Jines that exhibi t various degrees of di stortion in both the posi ti ons and the intensities of the magnetic components. The in terpretation of these asymmetric patterns has bee n made by t he approximate theory of t he partial PaschenBack effect. The g-values that have been derived fo r several energy levels of Mn I are found to con form , in most cases, with t ho e req uired for LS-co upling. A few excep t ion s to t his rule have been considered in so me detail. General tables have been computed , which will permit explanation of th e distortions in other spectra.