CRYSTALLINE STARK SPLITTING AND MICROWAVE RESONANCE ABSORPTION IN PARAMAGNETIC SALTS C. KITTEL AND J. M. LUTTINGER TECHNICAL REPORT NO. 49 September 10, 1947 RESEARCH LABORATORY OF ELECTRONICS MASSACHUSETTS INSTITUTE OF TECHNOLOGY I_I __(\_l·_II__III__X_- --- -II1I-II--·--- Rserch Iiboraory of nlectrmics chnical BRport No. 49 OUSCbLLM 8epteber 10, 1947 ARK SDPLITING AID XIICBlOWTVV IN IUfIMIC SA m ABSPlI0 by 0. Ittel and J. n. lattinger A theoretical discussion is given of the applicatio of microwave absorption measremuents to the determination of enlrg levels in single crystals of pacraei salts. Selectio rules are given for magetic dipole transitions between sublevels in the presence of rystalle electric fields of cubic tetragonal, trigmnal and rhombie sy trT. The Zeeman effect in the presene of crystalline electric fields is disoused in sow detail for three speal olses: a) J /2, cubic field; b) J 7/2, cubic fielad a) J 3/2, triaonal field. These eamples ma correspond to certain matically dilute salts containin r Fe , 't and Or + ion, respectively, provided that exang interactions o ot plar an important role Numerical tvalues are tabulateds for the rlative frequencies and lie trengths asoiated with magnetic dipole transitions in the oases disused,. he character of the spectra may han radlally between the limit where the Zeeman splitting is ml in ceaparison with the Stark splitting, and the opposite lrit where the Stark splitting ma be neglected. ..___ I --____r_---·--rr--rn-·rr·rr-·- -r-l-rrrrrura--;rrwunw-rsi I'·UICI-L .*yllll^---··---- __1_ _ _1_11 _1_ I) - I. II, iTROD1,CI-IJTi 'fle present kno-rleuge parai. agnetic salts is of measuremnents of of taute eived fromn t-e i'lter-rftatJ on largely speci.ic he.ets, s, agnietic susce-l.ili'iitie a'.sor-ption snectra. anld otical quan-rt';iln ' of t.e Ihe difficl-tic ivting il a consistent account of the vrious ?heno-n:'le '1.ve been 3 19)39 Strasbouirg confece sized by Van vlec'- at te :Tnd by , Penney and I rnch5 The recent exoeri ietal discovery b, Zavoiskr 6 of Dar&-lmagetic resonlence absor-t-ion provides a new and direct metod for th in a;l-terials. pDara.lagnetic field. (1) s : nt~ situated .lced in an r-f circu.it elei e, The Theory of ilectric and ilag.--netic SusoTU Univers . t,, Pre ss, 1' 2 tre s L T e i; 'Ver n1 a1d , . ianet rss, (Ca;- bridge Un-1 Iversity Prsne.. 3: .a.P.r d Strasbourg, Le,r.nt s'e Uiversite . lec{e oo--pc=ration I'i ntiona! era t netis-e (Institt Tue i, Pris, (4) C .,Gortt (5) 1) ti.G..Penney (6) uantum transi-t.ions J.IH.Van Vieck, ceoDt ibilit ie (2) T.B .C . Cas iir, (3) c'serving ic freql-ue-ncy or icrowave electronagn-et a ra.do The salt o Th e -leth,od ccons;ists easure:ents the by mreans of' electrsicel ilsduced b energy levels ivestigation of closely spaced ( 1 940) Plran-o-etic ibon]_slevier, iel:, Amsterda-n, SOC. nrid G.J. T yrinch, Froc. Po,. , Cleo:k. V.,r see also JTi.ian VecL*, (9 Z, l/o2) 10 P Freed, Rev. i Io......>;. , 2 9 U..R. s J. hys. E. Zavoisyy, so R L :orow se e a-' 57 C(19-6); 1 1, 170, Phrrs. Rev. ________ __ _,_ ,_____.. A170, 112 (1939); S. ,7 (1937); 5, 47 ( 19 a ,d 5); D Ha l.idav, 70, 433 (1946). ..I_._.. .IP-^----------- -.1.-- 1-·-----111·11111li As th -e stre-.th between the pole pieces of an electro.;magnet. owe:r, absorptio:.! in the salt of the static field is varied the found to -pass through a well-defined rlaxii.mm. is reorted by Zavoisky thee posi- In ti-he rsurceents tion ofl the resonance satisfics close'v the Larm:,or equation for electron spins: 2/i where HI = frequency; T' 2. 80 mc/Oe - field; e Letic lc d.c. ectron:c charge in e.s.u.; i1 = electronic i.ass; c = veloci;ty of liht. The aLicability of zq. (1) to wSi 1ch te free waEs pointed out by is sin the eapi'erii:ent is condition, lctron states il so lHds renke 7. in Under this to thie nuclear imagnetic a.aloous resona;ice ec-xer.lent i On te se,,. ;ictt-re o- -?re are affected i ics energy levels of the paramagl-letic inhlo.ogeneous crstall iire iway by te o.or ,anit whi-;ch are caulsed largely b sflittiig This f:, the tlhe effect situs energy levels of the free ioiis. an irm- ctric f ields, .io lents the dole Thie crystalline Strrlr hydration-. :r.r:la.gC::etic solids the .ater of do-goerrate of a s ingle level into several co;0.:ionrents r-cl;es possible the occurrence an r-f field of .cagnetic coI:ponenits, second ef-Lect the of the s...Di-ilttig is eeilan efect il _ -1 J. C---·Y~·-·~·-· Frenkel, L ·- P·Il a stac.tic to c' .ne i-lagnetic f'eld. the clractr A of -:agnetic ield: under certain a stctic t er:ect to fiZnd severa3 lines in the absorp- conditions we r.- (7) di)ole traisitions between the sit tlie absence o i eve in J. - Phys. U .S..R L_/I__ __^·1_II· 9, _1_··_ II_·I 2US (L9i5 )_ll____l_·rL_____.·II_ tion s ectrum, in con-ltrast to te In Sect:ion II sin-lc line found by Za.voL- -er of this we discuss sono a. Lects a.bsence of the of 'iicrovave absortic-on spectra in te effect (Ho=O). I', Seciion line Stark er:,ecvs a re co i- the icrowave "ioa1_s refer-_ to sizLu..le crJsta.s, tifields along-u crcystal , ra-;. .o.L , -ive iCl r- staiC ., .. for etor~owdered seci_,,ens of th;llese salts s . Sitla- of olIr clcu'la- . l wi.th of hih xe. .C..J. a-nid wou)tld p-roba'-, rticular .si-.ered.'r ;h.ree of .- iltOSt co.l)ined Zecl:.an an-d crystal- III te t- o is 7eeman .. and r-f '.'r,~,'-1 s itIa t, ion )1 extrez_: -_...i.rt co.<ica-ed, 'si - tt-, 1.. l crys ba Is. It oss ib e thati; E, is betweern ions. is perla-ls one of c r, sona 1,)c e .pc;-i deter;inod by oar' i:nc t ii fc cases of crvstai:ne are prese-ltec. only as calcuktLaio c:11le n _ .e I ar .. t; n coU-lig, ilof.straio ,. of thle coru:.'on situat io-. ap:'p-,11cab le l,tejl - ' JVarious _ · _I 'lt 'Tct.tS e s ... 5~-~ 2. of cCage ffcts in a ind of behavior f t ll' O Co -)u-1d.i .cr whrlich is ·IIIII^_ ·· Y*l·Y·-Y--LI_-LIIIC-- our strong ox1st are to a.p-ear the Physical leview. _, . -·II^-Ql----· ci- in this --:aer -i. th--.o i ex- -g cup.lig. ex.chnnge interactions; .22 .. considered ')7r J. HI. Vcl Valck, in i-)i' he slitti.c :siored trctoCd in t1ro absoe-lcc o_: to be e ly Sstrorg i-.;,ss . i n-,ortant .toi'e wt -ase revalence of s.cl Thle t-he i i; ntlber of salts l rill be effect of the St-rk -ltti; s change coupli: n -··1_811 - II. 4 - -IICROU' AVE ABSORPTIOi CAUSED BY CRioTALLI. STARK SPLITTING The usual tcavrk. sDlittnLs in crystals are of tie order of sor.e hundred or thousand ci-; in stances, how.ever, the splittings are o the order of one c Tnis is the case tith somie o cooling expori:elnts. the sl certain circlum . s sUu-diied inti Gorter 4 gives the fol.low- For exa:p;].e, ing overall splittings of the ground state: Gd2(SO Gd2 (CO4)3 10 cm -1 0.0 1 .081.2O 1) TH ,0 CrK(SO, ) . 12 HOO O. c Fo.iH 0.13 c1 4 (04)2 * 12 H20 Splitt!i.gs in th e ne'!ihborhood (.o principle accessiblie methods. 1 are in to investir-ction 'by -means of :,iicro,!?ave The selection rulehs in nagnetic dole one c 'l transitions enral Electric oermit a nul:ilcr of diole trai.sit ions are forbidden by the parity- rule, siice t he parity of initial and final states re id:"ntici the same dgeneratoe i:hei level o tles stat;s originate from the free ion. Electric quadru- nole transitions are less DrobalAc tIan ;arinet.c di-Dole transitions y a factor of the order of (atoi.i.c radius/wrave- length) 2 x (Debye unit/Bonr i, ncton) 2 , of 10 - 12 for = 1 cm'. c ilagnitudo of the The rhich is of the order iffect agnSitude and dtectab-ilitv of the resonance absorption effect :lay be estima.loued by reasoning similar to _ II _·LII1__IPI___ILII__ LIL-- ..LY----- --- XIII_·Y*·LIIIIYyl-l------··-···l· - 5Torrey, Purcell that given b :for the case of nu- Pould and TVe shall consider thice clear resonance. -owerr absorIbed by a syste-m wihich has ;two eignstates 1 and 2 wit- X0 ferinlg by the cnergy elgenvalues dif- The trnsibion probab between lit-iy states i and 2 for a silngle sste'-i per unit ti:.le .. r x-polar- izod radiation is tx2 is where U-.12 2 (2r-/' 2 ) p (2) the :lmatrix clemeiint of the -anletic lo-.ilet OJC-r- the total oerg;v ra- i1n the i.c.d..t tor p= g BJx and I is diation ield per unit volume per unit frequoinccy interval. In th ground state is the uilmber of srstems in eqilibiriu-l the ri.lcl uimber of syste-mls in tlie ex- greater than th-ie cited state; the excess is Ij -1 '22) (-T for lle tota is {o0'/kT << 1; h.:'re kT( IT ) Yl(I e ncr o The ' s',,steis. -,given by porer a'Osorption is 2"'T (yjo) I h f t'i Su:?-oseO tiChat the badw.;wcTridti () p i,n olectrom-lagnettic cdnt to m.-;Le- (e widtl of 'lhe resc.na.lce lim- tic nom.icnt interactions) is Am (>> Af); then only the fraction wave is Af a-n; 2tr Af/zlo witi-ii t te toof +thetoal baididith . o -un--ber -lthe of sstemi;-ls r-f be tl.e total energy density in raiation ave their resonances feld. Lo t U = If the icident radiation fiCl.d; then(8) H.C.Torrey, .;ii.Purcell and R.V.Found, Phys. Rev. 9, 68 0 (1946) ·rY---------·----^- ·-- · IIYIIC-·P--C-·--rrrrs- ·Il·rr--rrY1_.·u------·-^r^---rr_ -^------u-·--··-··-r-rr--r^-suuurx -- --··lll··l-·m·-· -- ----- -62 T2 l2 12 n 2 p _ 5n U 1=12 kT Ao is the integrated power absorption per unit volume, is the number of para-iagnetic io:ls ner unit voluame. where n Nlow the QI of the systclhl is given by o 2 if q. From 200, w-rhicl is casil -Awo 300= or T one hs, (6) = 1 c- , ald , -:s;cc te detectable rhich '.'iay be of theC cavity Q's n2 2/a3 so that interactions, -Q considered as caused by magnetic dipole the line width is oe C:pt Oi tis lre o.t orcder of 1000 or wavelen-gth. Selection Rules 'Te out .1ailb- the allowrd transitions are have C.oited iasj;na tic dipole tra':-sitions. scelection ru]3.es groum, o'r -tioret-ical itllods. ti nos ccrrespond'..n.cl: to the enicrgy levels i electric fields transforisentations accordi.ng -to The ch.r.ci;ters of te ,h in the paers of Ct The1 caigenfulnc- the cr-rstalline the irreduciblo1nrere- of the symmetry ,g:roup of thi Pi Tisza 10 field. crst11 irreducible rcrcsentatlons -re 'ol the One c n proceed to calculate and Jahn. (given I0 The character of thCe magnetic ;mont operator under a rot;ati-on t-:.rogh an angle cp is given by y;(y) = 1 + 2 cos (, siicethe Arn. der hysiil: [53 3, 133 (29) (9) i.A.Beoth, 2, + (1933) ysik (10) L, Tisza, Zoits. f. , 117 ('93) (11) H. Jahn, Proc. Roy. Soc. A - agnetic - 7- mor-ent trarnsfor-.Ims as an axial vector. It is a unda;eontal resil't of grou-, t'heor tat transitions are allowed betwreen levels m and n only if x rn here ra a contaLi s '6ie identical representation rl; x Pr The allowed tran- is the represe-tatioun of an axial vector. sitions found frol t-he character calculations are gi.ven bclow; the represcntations are lab.elled according to te Bcthei . notation of Tn t 1he cases of the one and two-valued rhn-.bi'ic arnd character tbles are £ivCi the iven in detail br Btle, trigonal groums, which wo-re inot in Ap-ni- A. indicatcs tat lt Th e nolaticn. th-e enorr-v - vel hose eigenfunctions belong to Pc has allowcd rianetic dipole transitions to and from the en-crgoy llevels whoso cigenfunctions belong to P Cubic Gr"oup 4 1,3,4 and P b - a .al,)i -- 2,3,,; TrOa-,A( = rP + '5 Tetragono¢_ Group ("axia Transitions for J: Transitions or JJ Transitions for JX Jy 1_ I----II 3(z -P -, 1-+ Transitions Transitions for for J: Jz: F C _ __I_ = r ,22; ) ,33 + r, r r, ¥) ;Pi'5 s;'+ P66, 2,3 r7; 6; r 7- P3;; P;6; 4-+ Pf- P 33 ; 3- '3; P4- ~ 5 xyl~~~~~~~~5 IIY·-LII-·_1---CI--L·II(IIILY·_L_ 7 6; "7 r7 r77"- F50 r5- + T- IP·- r5' F I _I_ -8- Rhombic Group (raxial - r2 + Transitions for Transitions for r3: r ,:P 1 4- Transitions for P(x 34- 4; P5- r3; r 2-- F 4; r5 P4; £3; f -L F2; 2: + r 3 ) +( (Z) '5 I5 15 - P. r The selection rules for the tctragonal case have been given reviously by Bthe1 2 . rules nay be il- The application of tlhorse scction lustrated by the case of the Gd ++ ion, for whic J =-7/2. According to Bethe 9 the ground state of thec ion slits cubic field into a two-fold degenerate a two-fold degenerate evel in a levcl belonging to 6 ; belonging to r7; and a forr-old degenerate level. belonging to r. transitions between P 6 and Fr, The selection rules Deriit and between 7 and rP, but not between P 6 and rg. If the overall splitting of the ground state in Gd2 (S04 )3 . 8H20 is 1.0 cm 1, as given by Gorter4 , the allowed transitions will correspond to rwavelengths of 1.6 cmi and. 2.7 cm. This follows froml the fact that, if only the cubic term of the fourth degree in t he crystalline potential is ered1 3 , the splitting is consid- in thec ratio of 5 to 3, with the four- fold level between the two two-fold levels. Intensity Factors Eq. (5) is a quite general expression for the pover absorption when the bandwidth Af of the incident eleoctromagne- (12) H. Bethe, Zeits, f. Physik 60, 21 (1930) Purell, J. C er. Pahys. 5, (13) I-I. il. Hebb and. I. "~ -" .-"~I^IUI"IPsl"L-IP--·-···IIU·II· ·-·-·-----I I---"p -' 338 (1937) ~I '----"I--' -9 small in coi.marison with the effective bandwidth tic wave is .00In the absence of 0 o of the resonance, and for kT >> detailed knowiedge regarding the deelndence of Awo on the cryand applied magnetic fields, we shall su-,-pose for the stalline a constant for any secific A0 is sake of discussion tat Under this ass-,lmtion t he de-endence of te power absorp- salt.. :a-gntic field intensity is determined by tion on frequncy and co 0 2 1 or tho fact 2 2 in (5). E. 7refer to discuss the di;:ension- For convenience we less quantity: This ratr; o lar lmoi:olriltUl actor. sitsit be called the inte ill (7) In)/12 )2 I/ (J ( 0i Ter c J is lust be defined -is an energy whic!h closcly rel.at;ed to the pure- is for each s ccific '--roLle. - it thec angu.- 1-l cr-ystalline slitt-ing. operators J = se CD7oa-tIly. Jx Jx orc convceni.nt; is In gencral it = J. J iJy y anc + .. iJ,, - to Tor' with the J . or J y thlan with . ;e ha s °xx ~ 2 (' ( -t J- J_ ; now from the reality of Jx and Jy, (I J -in)-- (9) (n J-m) so that (mirQxn) = ((ra.>Jin) + (n+J |r.i) .trix This rclation is used to calculate t;lJx fro tose ) ' (10) elenlts of of J. Tables of nunmerical valucs of the int'liS ty factor are given in the following sections along pith the __ ______L-·-·.sl---· I ^·-LYI"-IUW.1"··-L-*Y^I· -- . cnergy - 10 - differcnces associated with the various transitions. III. It CCiBI:LD CSTA.LL T is ANID ZEiIA1.T SPLITi],4G cncral 'fas.sion ossible to discuss in a not the belvior of energy lcvels in of co:lbi.ned -brsencc thc crystalline electric fields anld external static fields. -.cnetic is necessary to find in detail for each Rather, it quantun individual case the solution to te mchanlicl er- turbat ion proble-m. Level sJli -ttinus corrcsponding to quencies are believed to arise only in uations (a) rc- scle-lct s!icial sit- includiiLg: When te ground sta--e of the frce ion is fiel.d causes slit-ting only i the crystalline uwith sin-orbit cou-lin (b) icroave T mlove 'the degeleracy highlr hishr sylnmtc'cry. symm,1etry. ilay have a sall conj.unction t s small. crystalline field of loJ srym te-try :.a -y re- ll A s Te rsultnt an S state, eft argser crystallinc fcl!d of by a Ft'or For ex~lo,;, trional aaxa; D)redoinantly , cl;u _ .i vcs rise to a .. whi con c field .... furt-cer splitting. Hebb and Purcell13 magnetic coolin tin is e xperiments discuss exa:'.?hles we;re t:he slit~manitude o o of the order of split;ting is of in their theortical stud found, for oxamcel, o;nc c -, Tyoc (a) in salts of trival-l't ado- ++ linium, whorie tle ( 5/2 ) . (14) 14 J. ;,round level is Type ( b ) sitt in is 3/7; found H. Van Vlccik and "T. G. Penney, --------·-C-·-·-i--w·--rr-rP---;I^· -·-c-·--··r-r---i·*P*I-··IWII-L-II and tih and in Fe ++ or exale in potassium Phil. HIag. 17, 9'61 (1934) - chromic alum (KCr(SO) 2 1 - . 12 H 2 0), whore there is thourrht to be a small tri-oonal field superposed on the predoviinant cubic The possible transitions and corrusnonding field. intensity factors for the cases just cited arc discussed in detail below. J = 7/2 (Gd+ + + ) Case I. in th-e absence o is external -!magnctic split by a cubic electric field into two two-fold levcls and one four-fold level. According to Bethe (cf reference 9, 155) the two-fold lvecls belong to r6 level to Pr. in fields this state tIe p. and I'7, the four-fold assulre that the splitting1 5 tabes place as , which is consistent with therc orik of Hobb and Figire Purcell1 3 The zero order rwcave functions belonging to these reprosentations are listed below. (15) __ However, the situat-iion in the Gd + + salts ay not be so he re indebted to Profssor P . Bclinfa-tec for siL.ule. eli of tie energy corresondencc regardilng a detailed trat Van Dyk and hi'r'sel. level schceme in -)re2)aration b',' I I I _I_____lll___l_·LI_.La-LIIULII- I..^ylllll^^--^·.-L1-·ll ____ I___ _I - 12 *a (1) _1 2 o5/2 ) ) ) ) r7 ) - o.3/ 2] l1 "a (1) (i) =_r1 K-5 / 2 - 03/23 2[32 1 37/ 2 fib - (5/3 52 1 (2) = (7/12) Vb (3) C c;7/2 - (5/3 -7/2 T1 ~. [-t.5 YVb ;-. + 3 21 2 + 3 C ) /" ) 1 1 - 7/ 2 + (7/3 5 ) '/2] ) ) 1 (2) ( 5/12 ) ena denotes q7/2 + (735 1/2] a function with J = 7/2, iIj the secular equcation in the ?rescncc -^.··C--IIl =I. ,JWlobtain for of an (001) directed mag- netic field, __ 1_1 ------YI---C ICIIIII·_Y-I (11) I-------· - 13 - (1) %I (1) * (3 _C_ I (1) ) a ( a V3 ) 0 =0 -E *d?(1 ) T 35 a 0Q -E U1 0 1 0 - (12) V3a 3 a - - E 3 0 a (1) ~a _3a " _. L i: -_-~I 3^ a - - ' Here a = gBH(g=2 since L = 0), and there is a sii ilar block involving (-a) for (a) and the reiining functions. sult has been sscntially conne ction. other ii = E/ ,x= a/ iven by Hebb ad Introducing diCcsionss one finds for th-l Purcell in anquantities cigcnvalues - ____ _·-LI-lll-_l--_I 1(1·III1 ·--CII^·IIY ·- -1 I1I ^--·-LIYI-L-P-_--PI^·-·Yllll^llllli··- This re- CI - Z i-13 97/2 7/2 x /22 r1 3 / 2 + 1 -2x2 +2 + 1 ~X+ 2 2 3 3 1-3/2 -2 ' T "- 12 x 2x 5 -+ 12 (5 3 13 l/3 rr,-7/277 2 + 12 x 2 + , T 2 ~/ 2 2 221 , + 2 1 + 14O2 tT 3 x) 2 x + 2 9 + 12x2 2 x-x+ --1 1 -5/2 13 , lj22 - - - 140 3 x);9 (3 tT.2 22 14 2x)2 x X )13 + 12 x 2 + 140 2 2 -9 lts being labeled according to the levels they r.rescnt the These are plotted in Figure 2. in very large fields. The numerical values of the frouoncies anrd intensity factors m-.trix " corrsspondin- to nol-v.anisin found' in Table I, while Figurc leonts are to be 3 sives plots of inten-si-ty fac:lagntic nd frequencies of typical lines vs, aied tors field. The sum of the squares o of J x. is all the matrix elements exactly 84 for J = 7/2, indDcpcndent of teo vaclu This result followls froml t stability (cf. refcrence 1, p. of priaciple of sctroscopic 139), and provides a very useful erxprcesThe authors have available copies of the aaiytic sions for tic wave functions and imtrix: clelicnts as fmrnctions of x for distribution to anlon, ---I -IIIL--ll_·_Il_^·llllll^·--Y··-·)··111----·-· 111 -rm. -·-Il-·.X·-- o ;cay rcculi.r them. --- - - 15- chieck on the nunmricai calculations. For strong rix CeCijenCts ,a;:ntic aplroac From Table I we fiCilds the igcnvalcus and *mat- i,..values charactristic gOst values of the intositJr -a8ctors bClOn ized transitions -± usual selectio ' 7/2 halch_I t r- -i-)o]ar- tso 1, in agreeCent with the n oxa;-l le of such a transo .c . 5/2, for whiich the values of the freq.uency sity factor are slown in Figure 3. weak for all : an exanple is independenlt of x; an Figure 3. 3/2i--* oints o (Figure 2) corresord to lines Case II J = 5j2 (Fe +++ All o of the intl;sity factor, te The cse of J = 5/2 is the 1/2 sho1m lectric fild and also by Kronizg and Bouwikarp in ienvaluo diagram ) vr- si.ila, to t'-hat of J The roots of the secular equation for an (001) field and a c..bic z- -ero frequency. of l ++ and inten- -7/2. xanlle is the line 7/2-- The crossing is A number of lines are pola rized lines have conistant values 7/2 . free ions. that -for liare x the lar- see, for e:a:1nl., or o havc been ive b ianetic Db.r 15 . iJe shall not discuss this state in any detail, but morcly give rsults. (15) (i) The energy levels are P. Dbye, Ann. dor Physik C[5 32,85 (93J) R. do L. Kronig and C. J. Bouwar -p, PhysF;c ___lll__l__l^_lg__lIII/YII-·U·-XWY-LI- ·.I___.I_IUIIIIII1--^- .... , ·.C^IIIX-LI I-1I_----·1II*I_1- 290 (1939) -1 IP_-·II- I I 16 - - E1/2 = 1 + ½ x - £_1/2 E5 / x1 1 2+ + (3/4)2 +x 2 _ 2 _~~~~~~~~~~~ (14.) +a /2 2-- 6 c3/2 3/2 - -2 + -x (3/)2 2 +(3/1)2 2* [x + 2 x2 _- + (3/4)2 2 where as before x = gi BH/c,= E/o (38 beilg the overall splitting in the crystalline electric field alone). case under coisideraion, just as in In the the 7/2 case, L = 0 so In Figure 4 one finds these energies -- ottod as that g = 2. a function of extcrnal field. Table II gives the numerical values of the frequencies and intensity factors. ri ci-ple of sec-tIroscopic stability apliod to The the J = 5/2 case tolls us that th the natri; elemeints of J+ is Case III (KCr (SO 4 ) 2 s 35, independcent of x. 12 H 2 0) According to Hebb and PFurcell the Cr + salt is stal lin in a 4 F3 / 2 field. If ion in tis state, wich is not split by the cubic cry- llnt a one assumes that thlCre is also nrese s;lal.l field of trigoc.!al sy,rlnlitry the axis of which coinc-ides s of the c)ubic lattice with onile of the body &iaeoni. to be xpected fron I.-ra. studies of 'the 3/2 state does split and give crowave absorntion. _1-m-I ·IIIC··-----·--..l·(Yen· all of the suares of i:ow'r in rlse to sle t) t hen--, the J or ossibilitis .h.s alum the Cr++ · · __I-IIYI·CII*-·---1111- (th.is is mi- ions lie on i "~^~~I'~-"I-~x'-I~ I-·lilllllU--·l· --^-(·1111_--·1-8·L - -17 Tf one rsolves t, :a-cc-e z1e cubic lattices. vicc into on iiontrenio'at:ing sirm- i.e., a face centercd cu:tbic 3lattice, lat- the four sii!ple cu ic lattices thei cc finds tat the trigonal xis cf' th. electric ficld is in ceach c aso along he1 dig.onal of tc unit cbeo. a different body tlcso four Si: 1 lZe Cibji SYvstee il.CC:,-wldC.; c for' th Thki'' .. t'rixol 1 . notcnt ic] only the soco 'ci rstalline orcer dor1mer ~s we!r' j .1 V, whore te xi-s 5is he.co t a z tont ial iias iorc as a result o t'she (001) - ' our dr ...s nr' c ry. gr , h ;:ir, ho'> rcticon arnacn trf''oj-eal' lc ra t f iitccoiponni,_ arrays, OX placed f" -l c lc .o ; is, . ro.tios o.-;.o i. . d shou.d coe 1 t;-T f:"icI - di- ni' ct.t, ..sTidoI ,I e .;n,,o>. V,:o onlly t;he 0i. ;.c 'it1- triC-'onacl ac:i in directio n.. the (.11) -to solve te-ia -;robl ow .ve uie 3/2 -erbturbe d r ;'= trig F3 to be, alo n _ ___IIIIII__^__/IILIslP·II)··--_llll- of .n ..t o, with J . iitrcction H For a s;,y:' syi:l- try 3.Ce:1s, ,:)"i-.tic ri nd thl-e axis. Jlst ' -T Tlls .. ax.De') it h er \S. o3f te states.. as fu ct. Gios of t) th ;ield (15) l ( . dhi"s-1o i ' . . d'irc. 1... ti. cauic the st--rcngth o - 2z'" h h.n: s-Tm:l.CIr7 each Coi r:onrtt si:e-.r onel 2 - cian tri.goaal (i this apa-ront ail in 2 = D ( + - HE-* + X(i 'Takiwi state g 2/5. t dir ctior, (l." . J) (16) the d:iroction of ua.-ti%.zation and choosing t C x and y axes .(l--·ILXY-··_II21YL-l III-CPII^ -^-_I1_I1·1---- 1 I I ---·- I ------ -1--11 i - such that the comupontent of H to th'.- z axis lis r-lcricr equally between thci.l we have = H . J Hmg (Jx + J C (1 (l-i) J iaag where + J ) + + or (1+i) 2 (17) Jz ) J_i ( -, z ~ 1 a. The level schemne in the absence of Hmag is levels are lcboeled br thci Here -,hi 5. in Fiur wirakz fielc Ct as Cor:' , ing now TH tio we nruag Irntroduc quantum numbers. ssown secu-lar equation: 3X/2 _1_1L/2 :_ 31? 1 -+ 3/2 I- 2 A." i4 IL i X-s 1 l+i 3 2 x x 1/2 - 3 _ I- -- Exp-anding I -- --- = 0, _~.r / - 1+i 0 L-'L.C -x:-. , -- Y :7 -- 3 - I-L 1 - X #- 2 llI IO (I-i) _ I'_ _ _ _ 1 2- x - 3 x - 3 (i9) l- .. gives l _ 1 ( 2 + 15x I2 )5,,- thle roots of whiclich __III_-YIYI-··---Q---·ll.. 0 x 1 X - _ E/5 where (i-i) I (i+i) - - 3/2 0 2 " 0 - 3/2 /2 C 1_ 0 1/2 - I 12 ___ .-CII--ICII--·l-CLII-Y C2 T6 (1 + ("lo~- - 2 ) = 00_ (20) (20) ro 1-1II_ - l_·I-_I-IY*-U·----·--YI.IC--- 11II 111-11 - 19 (-2 2 - c(-L (1 whre sity rules it It E(i1) should be r 1fild alon1 nu-bers. ing 1mu\-ric he 1then Por an r-l ,roill. p:. for example we wll _. not h ave onlw C. s a,e-, inti li f -f the field. irected ai o-g ti':o (001) ficL.i is r-f + Jy + JZ of J lents the ;.m.rix cc to The wave fu.rctlions and tkcn correspond- i vJ tile r',t Jz t'. ' J+ relative re ;'ust. ko-.O the directi-Lon of lines for exa pl, _or are Ji Z ( of J+, re to be frced in Apc-Lx lec:t-ts difforont axis 1u c tions trlx "i l-;nts thcls i ntr- order to cilculatc thC relative institiCs In If, vr v c usJ d i;' t- axi.s clcier-jns -prscet. JZ t oleibu;ud thai; a-ro-riate -n ~ To find thle slcctin also the ad nbi-:c (00) 1/2 en-rgies with their of ql%.1;"tizabati the sstc., -2 + (21) ) ) ) )I x ) 1 /2 + necessary to find th is belonging to - 6x / +h'n15x 2 + 6x ,1 Ae '.a:velaojc.d tc strong field quat-ul x2 )!/2 x -/1+ (1 + 15x - -2) WflC1' wehvcbl' 1 x2 + (1 + = c(3) = T. ,l ., 1 C. .l c t Ln L z iv" clcu- A sil shJow.rs I(MiTr11., 2 1( +. I + Rc JT+ 1t )12 + (i:J+ II ) (Z[, t (E jM' I+lj 1)2 + 1(M/j1M1)~ . JIj+(() ) ((-:J [ ) + I Ii,-).1IJZ (1t + (: J 1 _) ( ,Jz Id,)) (22) +Im (I!t _ .l;-')(Z'jJzl ____·_II LLLII·IOTII-I-I..I.11-^·1111- ' )';" ----·· LII)I·.(IIYI-1111-- | __I ) ((IlT Jz II1' )) -I·I.I--P·I-UtUY Y-· - I- - 20 - actors for tls All of the intensity This is s ia ll, fu;nction of x is scon Jfrom'J the usual sili.-f spctru-. of d Co . CL-S.0 which is expected to b s ph . again t.1. th Tic ions oaraa~lnt. lilgr between considord, ay well that at . of t is Jct were m ade on m. not salts which thte r ' i;m.:ortancc i of llriday, lof CII--·-·-C ---- t- of it. ill:r sing sici.r2; One sou ..also ith the static crt-stls iigh syi.v-lctry. H. Van Vleck, C. J. Tisza for sv..vra' a,-c. nd discussioc~ns-, assistance. John Si-moil Gugglhin; the1l o' whlch We wish to thank Professors J. sCOmp~Utaj eonrll ing :lost ::-ost likely to bc realized I- 7 s: ald r-fn m-ag.letic ficlds a.lolg cr--s'.' a.ws of AClKi[ O(iLEDGi . iTTS and L. te;zure of kwh-icl I One of us (C .... ) eo;.cl-l tiS .--I·---*-·-)·111·_1·11----1- it h- - mea sure- Th salts wc have Ind eed, sort occ urs in cgnetIic:_ llr-colocenratcl situation which we hav,.- treated is in rspctrum. uln-row ard ad t of Cavoi.sY Ilents the ieffc-ts g.e'.: si anud n.a.-.y resitllt in a .Ll,-r e cou.- C.tir:uily negl.cted. h-s .,en This coupling iin :'cnry salts -lay su ie-ld. L exh.e LCf ii.lunC i a ratirhor _.ct - c com.lic.tod function of the cxt;rnal- static T1e wish to : based on the :icrowave absrp'tion tn-a crystals is ara;nagnetic as a 6. tle abovc treat-'Icnt, odel, field le. A plot of the oi_. given in Fi-;ur IV is -the r.f. ?prtly the consequ.ence of talin parallel to the static field. It are very cas; Fo-end.ti'c:.: t is Gortcr Kock for indcidbt cd to the n for a Fcellowshio dur- rork was carried out, -·--- -1*·14_--^-------_1_1·I---I 11 1___.__ A-oiend i A Character Tablc - ------Trigonal Double------ Group (after Jahn - ) -r ---------- rl E R 2C!I 2CI7 3C2 3C? 1 1 1 1 1 1 1 1 1 -1 2 -i r3 2 2 -1 -L 0 0 r4 2 -2 -2 2 0 0 I'5 2 -2 1 0 0O NUote - Pr is -1 O O used to denote two conjugte-co;miplcx one-diiien- sional reeT'c sent-at ions. .Cl.for the trigonali group is The splitting sc j =O .1l 2 '5 2 + P3 1 3 r 4+ 2 2 r5 '1 + 2113 2 2 P44 + 255 3 + r1 1 + 2'2 2 +2 233 _ ;~~~~~uxw ~ as follows - ~ c~· -·--·--1.·l---x,*lr~r,~·*u · ln.--·------~--- ~~~~~~~ ~~____.~~~ ~~~~~___~~~~~~___~~~ --------- Appendix A - 2 Character Table rC-·-·IY-I--I-----· - Rhombicc Double .Grou -- (aXtrr Bb BctcB ) __ 1 T EJ R 2C1 1 1 i 1 1 -1 1 1 -1 r 3 r4 r5 5 2 1 .1 -2 0 2C 2C3 1 1 -1 -! -1 -1 .1 -1 0 ..... w I. II~I ~ -· -_1^_· 1·~- Center of Gravity SumI Rule for Crystalline Fields Consider an unperturbed syste>.it wlhic-h has a definite J. angular momentum-. It undergoes a perturbation due to an ex- ternal non-singular (electric) field satisfying Laplece.s equation. gravity of te slow thiat center o e shall 2J+41 comlno- nents of the originally degenerate energy level is not shifted, to the irst order. erturbed system; Let the cigenfuncti.ons of the J+l). (i=l;., be 4ri levels 'Then the center of gravity of te will be given by g i S V VW 2J:-' = -Z where V is the .etl..io1 repre (I-- -J,..., use the eigenfunctions is unri a-nd i._vari'alt Te could therefore der choice of re;,resencat.;tion. system. HIcwever t his is simply tial. -erturring poten the trace of V in te dt +J) o just as well te unperturbed That is, ." 2Jv+~ dr V t:i " 2J-1 J' d V (Z T 't1T form, tne is rotationally invariant since te Z i"ii M4 irreducible representabasis vectors of a (2J+1)-dieisionai iNow tion of the rotation group, and in this the sum indicated is tion tht reprcsentation sace just a scalar product. V sat isfies La-lace's euat ion (which is invariant) we have that V variant solutions of Laplace's ecuttion ;.-*NlrnB^.Ws*IY·;·Y -.--·I-· l·-.·L-r·III*-sU--LYIII^ rotationally ulst tracnsform as one couplonent of some representation of the rotation group. shifts all ioWr by the assunlp- Since te ar. a constant onlr in(ich levels equally and just aounts to a ciialee of the _--1BC.I*- IM1IP IIIIIWW -i-iY1I-(. Appendix B - 2 oncrgy zero oint) and /r (whlich is s igulr) .e cC;: l sa the represc-lnttion to which V belongs does not conCi.i:' dent ity representct ion. tiieorotical argu.ont' Thercfor according to the itegral quired result has been inl i vanis'CS stablished. theore- h. s bly bioon g ivan prvio.s A the that the i- . ust-l rOUp .:nd te re- ercaker for-, of this hisy KyIlch Cf for exa.-DI.e, H. yri, J T.. tr a'ad Kibal , r.a.tu. Chemisti2y (Joiln ilae, 1ieo York, -rI. 1 4.!.) l . G. J. ynch, Trans. Farladay Soc. 33, 1402 (1237). 1 _ _ I_ Ip _I_ 11 ·I1I1I___1III l--------Y·lll PII-_I^-III-.·L-__X1_---·--_11 _ _ _ Appendix C This appendix contains the wave functioi-sand matrix element for K Cr Alum in an wave fctions (001) static -cagnti The icld. arc given by * b (I ) "3/2 w + where 17 s f 1 - 1/2 CI1 + -3/2 -- [· 1at,1, ++ I~l~rT Ibt 12 +- I cl." I + 2 I IIl eI) , (1 + i) I x 1 1 2 /2) - i(3 - -(' + 7 x ( - (l+i) - I) aII- 2x 1 (1 i) (33b2 /2) -- e(II)) hCmar elee2 The atrixcle3nts o 2, 2 x J 2 (a, 2 and J .. are now b * 7 cl t CII ~~~ ~-_ 3 - r' bI.l ' a,14; I T I I1 _.-12 `~-~~ ( t I i , I 1"'i, ) L(1+1a 1 2 + 1b ., 2 + I Iai, 14I I c 111I 2 )I (+ 1 3 2 a1 -1:) I(1+|9.1,|2 L _ I __ ... ,2 C·---·l-·llll-·l-;P·l-r--·--·l + + 2al ' ----c ' I .1 T I ,i bI, + 32 II' hA1 + 2, + 2I 1 +, (1,- I Ii + + tcI. 2)(T PY-9LY·IIIX--- + I, '--c- ^L-··-·-·L--··---LII-I -·L- 11 t2+b, 12+1 C 12) -------.^C--L-_·--·i-_··--L-·I- 2 r6 -t 36 . 56 if r7 Figure 1. Energy levels of 8S state after splitting by electrostatic potential of form V = D(x4 + 4 + z4); the over- all separation is 8& ·- - ---· -- ·--- ·---·--- ----- ·------·--------·-------------·- 19 20 16 12 8 4 o 4 I- Z 0 I)- 0 -4 Z -8 -12 -16 -r,' 0 14 12 10 8 6 4 2 MAGNETIC FIELD STRENGTH IN UNITS OF 6 /gpB Figure 2. ___I_·I ICI__^^__IIIIQ__I_ X -- Eigenvalues of 8S state as a function of the strength of the static magnetic field in the (001) direction; a constant cubic electrostatic field is also present. The subscripts on the tts indicate the value of the magnetic quantum number M characterizing the statefor x )) 1. --I·LV^ *I*·I^···II··I·IIIPI-··--_-·slP··I An e 2 100 QUO 90 1 -C 80 La6 0 70 Z z z 60 ° W 1 Z U J I.- z 0 50 O z a0co 40 Z a. C) Z U 30 LLJ D Cr Li~ 20 10 0 2 4 6 85 1 12 MAGNETIC FIELD STRENGTH IN UNITS OF 6/gP9B Figure 3. _ 0 14 X Frequency and intensity factor for ome typical absorption lines resulting from an S, state; the intensity factor is proportional to the power absorption and is defined by Equation (7). 11_^1__1_1______1__·.--I·*U·IY·II--- I__IIIX---· I I - 20 16 -12 8 co L0 4 z Do 0 -4 wL-4 Z -8 -12 -16 -20 0 14 12 10 8 6 4 2 6/9PB OF UNITS IN MAGNETIC FIELD STRENGTH Figure 4. 3EigenvaluBs of S state as a function of the static magnetic field in the (001) direction. _ I_ I _ _ __III__IIYI___- X-- __ 3 2 3 2 5 Figure 5. Energy levels for 1 1 2' 2 Cr(S0 4 )2 . 12 H presence of axial electrostatic fiedi. _ -- --- F___ III·L-·--^-LIIII··^111- in - -·--- I E u 16 12 8 i0 0 L) -4 z z - 0 Il) O w -4 z i -8 -12 -16 -'>n O 2 4 6 8 10 12 14 X-O MAGNETIC FIELD STRENGTH IN UNITS OF CpB/6V3 Firure 6. I _ III 12 R2 0 as a function of the strength igenvalues for K Or(S0 4 ) 2 of the static magnetic field in the (001) direction. _ I__ 11___ 1_II -C-L----WI·-O····^IP - I - _- - TABLE I Frequencies and Intensity Factors for Transitions in J - 7/2 Case: Cubic Field Table is labelled in terms of dimensionless quantities x - E b and x - gH/ The intensity factor is defined by Eq. (7) and is given in this case by I(mJzn)12 () Transitions 2 2 ,whereo is as shown in Figure 1. - ~ I(mIJ+In)12 ( )2 and Gz = . The static magnetic field is in the Z direction; this is ctso t-e (00%) dredon. Quantity 1 x I .... .5 .7 1.0 1.5 .23 .07 .71 .59 1.22 1.35 1.76 2.08 2.60 2.93 4.05 3.74 3.33 8.10 4.13 6.57 5.09 5.04 6.19 3.78 7.98 11.19 14.53 2.47 1.34 .82 * . .3 .I 2.0 5.53 4.15 7.5 10.0 8.51 4.51 14.51 4.73 22.00 4.82 29.50 4.86 44.50 4.88 21.36 .39 35.22 .14 52.65 .09 70.11 .04 105.07 .02 5.22 7.65 107.71 232.68 10.11 407.68 15 .07 907.61 3.0 5.0 I I TI 2 0 1 1 da 2.73 9.27 2.33 9.97 2.09 10.49 1.99 11.14 1.98 12.74 2.19 17.28 2.53 24.04 3.36 43.85 0= .37 .09 1.09 .73 1.78 1.63 2.44 2.46 3.40 3.35 4.95 4.14 6.47 4.49 9.49 4.76 15.49 4.89 23.00 4.93 30.50 4.93 45.50 4.92 5.00 5.84 48.86 63.20 6.53 77.32 7.72 105.98 9.85 170.79 12.40 270.04 14.93 390.78 19.96 697.32 .41 .04 1.53 .36 4.16 1.04 9.88 1.77 17.24 2.15 24.68 2.33 39.62 2.50 11.41 2.07 13.53 1.28 18.16 .55 27.88 .18 40.24 .07 52.68 .04 77.62 .02 5.00 5.16 76.14 89.59 5.47 105.55 6.28 144.42 8.15 247.28 10.60 419.62 1- 2 5 1 2 2 1 e s 2 2 2 2 2 14 2 2 0 0 .-1 2 2_ 2 2 -2 .66 .26 .66 .25 .21 .02 .52 .14 7.99 .10 8.08 .87 8.34 1.95 8.74 2.72 5.03 58.41 5.04 62.23 5.02 66.32 5.00 69.50 .10 .02 .29 .19 .44 .47 .55 .77 .61 2.02 .49 .67 .18 .09 .65 1.28 2.56 19.61 5.03 75.75 7.51 169.42 4.91 17.94 4.81 15.90 4.80 13.62 4.89 11.32 5.20 8.25 6.05 4.77 7.18 2.92 9.79 1.36 15.47 .49 22.81 .22 30.23 .12 5.11 5.41 5.80 6.29 19.43 20.13 19.88 18.72 7.20 15.83 9.05 10.68 11.18 7.08 15.79 3.53 25.47 1.34 37.81 .6D 50.23 75.16 .34 .15 2.61 3.49 18.41 34.87 4.18 51.40 5.35 85.33 7.44 166.07 9.97 298.44 12.49 467.63 17.49 918.01 .82 2.47 .14 .08 2.10 16.46 4.57 78.19 7.06 186.47 12.04 543.19 12.18 3.55 14.99 3.62 20.81 3.43 28.22 3.29 35.66 50.61 3.18 3.07 8.18 .27 12.99 . 17 22.81 .08 35.22 .04 47.66 .02 72.61 .01 3.18 18.21 2.14 8.16 .10 .02 2.43 10.34 4.94 42.84 9.96 173.77 .42 .08 9.58 2.92 2.56 21.19 2.31 18.08 2.09 15.21 1.79 11.36 1.30 6.15 8.05 .09 8.25 .68 8.56 1.44 8.94 2.10 9.60 2.80 10.84 3.35 .25 .02 .85 .12 1.56 .23 2.34 .31 3.60 .35 4.96 4.84 4.69 53.93 49.01 44.13 4.51 39.58 4.21 33.49 3.70 25.04 g 2.96 3.04 3.32 3.75 4.58 35.0 35.0 35.0 35.0 35.0 6.24 35.0 8.06 35.0 11.87 35.0 19.72 35.0 29.65 35. 39.61 35. 59.57 35. AZ 3.09 35.0 3.41 35.00 3.87 35.00 4.43 35.00 5.39 35.00 7.14 35.00 9.00 35.0 12.85 35.0 20.71 35.0 30.64 35. 40.61 35. 60.57 35. 4.81 75.0 4.52 75.0 4.36 75.0 4.34 75.0 4.58 75.0 5.57 75.0 7.00 75.0 10.44 75.0 18.03 75.0 27.84 75.0 37.75 75.0 57.66 75.0 5.21 75.0 5.70 75.0 6.24 75.0 6.84 75.0 7.81 75.0 9.54 11.36 75.0 75.0 15.13 75.0 22.91 75.0 32.79 75.0 42.72 75.0 62.65 75.0 3Z _ 45.16 .05 2.84 24.52 a _ 12.51 469.24 1.95 9.63 5.84 .32 _. _ 13.07 18.04 639.47 1220.2 1.44 5.02 0 2 3.98 4.40 35.13 40.73 .89 1.82 0 2 3.17 3.56 28.02 31.75 .30 .20 Z -2 2 _____ 15.0 2 ++ ~2 _ r _________________--- ------ _ _ _ _ TABLE II Frequepcies and Intensity Factors for Transitions in J - 5/2 Case: Cubic Field is the overall splitting Table is labelled in terms of dimensionless quantities c - E/S and x - gpf/8, where 1 4in the electric field alone. The intensity factor is defined by Eq. (7) and is given in this case by x and 0z - (m[Jzn)2 'A Quantity II -I As 2 1 AS 2 2 1 AE 2 2 2 1 2 2 2 2 2 2 2 AC AC .24 .02 .75 1.29 1.85 .32 2 2 2 As e 2.0 3.0 5.0 r ~ 1.00 1.67 .71 .30 .62 2.57 .94 .17 .77 2.70 4.15 5.62 8.59 .64 .76 7.5 i 10.0 -[ ][r (tOOl direcle 15.0 - 7.53 13.15 5.04 50.82 113.40 12.52 313.44 .92 14.56 1.09 22.04 1.18 29.53 1.23 44.52 1.29 3.70 4.25 4.62 26.54 35.52 42.24 5.59 62.08 7.56 10,03 201.32 12.53 113.92 313.76 17.52 613.55 .46 3.29 20.29 2.97 14.00 2.99 11.93 3.12 9.72 3.39 4.00 5.29 7.61 5.33 3.56 6.70 2.83 9.62 2.23 15.57 1.85 23.04 1.69 30.53 1.61 45.52 1.54 3.11 5.28 3.44 5.45 3.91 4.89 4.54 3.82 5.70 2.34 7.94 10.33 15.21 .27 25.13 .10 37.58 50.06 .02 75.04 .01 1.06 .89 1.67 2.60 6.99 61.02 9.49 12.00 4.97 112.68 179.91 17.00 361.10 2.84 3.71 2.91 2.71 .46 .17 .17 .02 z 3.45 1Ar 3.15 18.08 2.91 4.63 2 .21 1.37 E7-x VO- 3.04 16.00 AC As ez -, 1.01 .09 I, -- .88 .78 .37 e~ i7 .61 .25 As OX x - .23 .02 .10 tke t'The static magnetic field is in the Z direction;this ilso (mlJ+ln)12 ()2 Transition .67 .42 3.28 20.00 3.90 20.00 20.00 2.75 20.00 2.37 20.00 22.66 1.10 .62 2.70 8.60 3.36 13.93 3.92 4.97 19.14 30.79 3.14 1.82 3.70 .98 4.94 .43 6.33 .23 9.21 .10 15.13 .04 22.58 .02 .76 .70 .08 .01 1.03 1.34 3.01 11.34 14.18 20.00 10.25 20.00 2.16 .62 5.30 20.00 2.24 2.37 20.00 20.00 4.58 .58 .36 .16 6.40 8.31 6.40 8.31 20.00 20.00 10.25 10.25 20.00 3.00 20.00 4.58 20.00 6.40 20.00 .04 30.06 .01 45.04 37.89 8.00 80.07 13.00 211.38 22.11 20.00 32.08 20.00 42.06 20.0 62.04 20. 18.14 20.00 28.09 20.00 38.07 20.0 5.51 .00 58.0 20. -. -- -- -------- ------ ·------ --~~1~·--sll"~ll~~~~-I-- --·------ I