Rao, D Ramachandra

Subbaram, K V

English

IACS Institutional Repository

IfIIUan J. PAr •• Q. 312-314 (1969) New bands In the A-X system of CaF By K. V. SUBBAI\,w AND D. RAMACHANDI\A RAo DeparImBlII oJ Pk",iu, Indian ll111illlle oj Teo1utology. KtmpUI'. (1/t""lJOd 28 November 1968. Rems,d 31 J~ 1969. and 31 Mara. 1969 ) [ l'LATB-5 1 TIle A..n· X'X ,,,tem of CaP which lies In the region 6300. 5830A is reinvestlgatod I \ by OlOlitiDg the CaP. ,ample in a lSOV d.c. carbon arc at 6·IZA comont. More memo bers were observed in. each of the known sequence.! /J." - -I, 0 and +1. INTRODUCI'ION The A·X system of CaF obtained in catbon arc was investigated by Datta (1921). Johnson (1929) and Harvey (1931). MohantY & Upadhya. (1967) performed a part of the rotational analysis of the (0.0) band and obtained the rotational constants. A reinvestigation of the spectrum with high current arc discharges showed about twenty new bands in the known sequences Av ... ·-1. 0 and +1. ExnlUMBNTAl. The spectrum wss excited by burning CaF, salt In • carbon arc at ISOV d.c. and 6-12A current and was photographed on a 3.4 meter ]BCO grating spectrograph. The!:J..:= 0 and - 1 sequences were photo-graphed at a dispersion of 2.4A/mm and the b, v := + 1 sequence at about O.9SA/mm. The exposure times varied from 2 to 4 minutes on nford R-40 plates. Iron arc was used as standard. DisCUSSION All the newly observed bands are shown In figure 1 duly marked. The band head data and vibrational analys;' are presented In table 1. Good agreement wss found between the observed bands and the cal-culated ones with the existing fomu!ae. In.i. -X'X BUb-."alem: In the /:;v = -1 sequence. eight bands belont ing to p. series were observed out of which none were reported by earlier workers and Q. series consists of four new bands. In /)." := 0 sequence. one extra band in Q. series and two extra bands tu P, series were recorded-However. /)., = + 1 sequence shOWl only Q, heads and appean u If It has originated at 5830A and starts diverging towards longer wavelength side and aU the band heads appear to be degraded to violet. Johnson'. (1929) uslgo· ment stlftJ ft9m (4,3) and the head lies at 17145.6 em-I, T/ItI nUlllbe~ I m I " (a) l!l 0=-(b) ,6,1.1=0 (e) ~v=+l Ih~ __ "'''_ § ~ ~~ p :i.i:; ~~ z~ a CD «\I') Q "~--,--'--'-LliJ.ll l~~ z· ~.. ~ Z -_" FIgure 1. (a), (b), (c). Photograph showing .:...v = - 1,0 and + 1 sequences rcspecth;ely of A 27T - X 2E system of CaF. Newly obseryed bands are marked ..... ?" ~ ~ " ~ e-.'=' ", ~ 1l [ il § ;;' e-: & .'-< ~ ;:;' r jt ~ '" Newbandfin tke~,~X 8y8tem oj GaF 313 TABLE 1. NEW EXPERIMBNTAL DATA (IN eM-I) AND VIBRATIONAL ANALYSIS P, Sories PI Series 15951.6 J.2 16552.3 7·7 63.0 2·3 ;;.3 8·8 74.0 3·4 84.6 4·5 9&'1 5·6 16004.3 6·7 13.0 7·8 21.8 8-9 'JIm -'!: sub·system. Qu S.ries Pu Series 16008.5 11-12 16457.6 8·8 15.9 12·13 61.3 9·9 64.8 1()'IO was thought to be uncertain by Harvey (1931) since this end was not properly resolved and the first few Q, heads were supposed to be super-posed. In the present work this portion of the spectrum is clearly resolved and it shows that the bands actually start from 17146.1 cm.-l • So, this is taken as (1,0) band of this sequence and subsequently the band at 17145.6 cm- l becomes the (2,1) band and so on upto (17,16). 'JI'l' - X '1: 8ub.aystem,' The Q .. series in l!.v = - 1 sequence has two more bands and the band at 15865.6 cm-l in P12 series is reassigned as (2,3) for consistency in the analysis. The p .. series in t:,v = 0 sequence has three extra bands than observed by previous workers. It has been possible to locate the new bands in the f:,. = 0 sequence in the sub-systems from intensity considerations and expected positions of the band heads though they are weak and overlapped by fine structure of the preceding bands. The red degraded bands listed in literature beyond the fj. rI = + 1 sequence of the 'JIs1.-'1: sub.sy,tem have not been well developed on our plates. Instead of the diffuse maximum with its centre at 5853. 7A in the microphotometer trace given by Harvey (1931), a moderately inter.se sharp line at the same wavelength has been recorded on our plate 5, figure 1{e). This line Is very ilrobaly due to an impurity of barium in the cv.Iclum salt. 314 1<. V. Subbaram and D. Ramachandra Rao Thanks are due to Mr. M. K. Narain who has helped during the course of investigation. Thanks are also due to Prof. Putch. Venkateswarlu for his kind interest in the work. REPBRENCl!S Datta, S, 1921 Pro,. Boy. Soc. (London). A, 99, 436 Harvoy, A. F. 1931 Pro< Roy. Soc. (London). A. 133, 336 Johnson, R. C. 1929 Proc. Roy. S.,. (LondoD), A. 111, 161 MDbaDty, B. S, & Upadhya, Ri. N. 1967 In~i.n. Jour. of Pure .nd App!. Phy •. 5, No.! lI,m \ \, 

New Bands in the A-X System of CaF

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New Bands in the A-X System of CaF

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