Gupta, A K Sen

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27A NEW ULTRA-VIOLET BAND SYSTEM OF ANTIMONYMONOXIDE (SbO)By  a . K. s e n  GUPTA.[kcci'ivcd lor pitblit atwUf Jituc jn,ABSTRACT. A ne w ultra-violet band .‘iystcm, very likely due to a '2 —> ’ n transition, ha.s been photographed under moderately high di.sper.sion in the region a,29Io-A2450 in the j j emission .spcctruni of antimony monoxide. The band.s are degraded towards the violet and eneh liand head is it.seU double. Their vibrational .stiuetiire annly.si.s .show s that the lower slate (>{ this new system is identical w'ith that of the other .«y.stenis already know n for the ' uiolceiile,1 N T R 0  1) U C T T () NIn a recent conuiiuuication fSen (iupta, iQ3g) the vibrational structure analysis of two band systems in the region Af)b5i)-A32()u in the emission spec­trum of vSb() has been described. During tlii.s inve.stigation the presence of a number of double-headed bands lying below A^nou was noticed on the preliminaiy plates taken with a small quartz spectrograph of laige light-gathering power. 'I'liese bands have not been previously recorded. T'he analysis of their vibra­tional structure shows without doubt that Iheir emiltci the diatomic molecule, Sb( ), inasmuch as the vibrational consUmts of the lower state of this baud system are, within close limits, the same as those of the two existing systems. The object of the present paper is to report the analysis of these new' bands.M X 1’ li R r M K N T A LUsing the same liglit source as previously employed, plates were taken with a Hilgcr J'!. 1. quartz spectrograph, having a dispersion varying from about 2.2 A.U per m.m at A2400 104.4 A.U per ni.m at Aagoo. Using iron arc lines as standards of comparison, the w'ave-lengths of band-beads were measured w'ith a ('»aertHcr precision comparator in the usual w'ay.1) K S  CR I I’ T 1 O N O F T it K N H W B A N D SAs the separation between* the sub-levels is very large in comparison to the vibrational spacings, the doublet nature of the system is not apparent at the first s ght. The system is, in fact, composed of two sub-systems, the more refrangible and the less refrangible components being indicated by (a) and (6) respectively. The (o, 0) band of the b siib*system is a comparatively strong band at A2663.96 f>'Si3752t).g). The bands fo, 0), (o, i), (0, 2) and (0, 3) of this&ul)-systeiH are more promhienl in comparison to the f i, o), (a, o) and (3, o) bajid's:, Iti iliost of the bands Ihe heads appear double evidently due to the 1 -^fbvm and Q-form branches, ^fhe separation between these heads increases progressively with increasing v '-  or decreasing values.The a sub-system also shows similar characteristics with spacings prac* lically identical with those between the bands of the sub*,system. It isfurther found that bands with the same r', -- values In the two sub-systemshave an interval of approximately 0J7:: cm.'"M)ct\veen them. Thus the a(o, 0) band is at A251 T.tSg (i'=^3979(S.O), Like the 6-bands, they have also two close heads, tlie separation between them varying in a similar manner. The bands under consideration may Iherefoie he considered to be made in> of two groups, very much identical in theii api)earance.A^ eu? Ultra-Violet Band System of Antimony Mp,noxide 21^V 1 R R A 'r I () N A L  A N A J, Y ,S I Sable I gives the w\ave lengths in air of all thcMneasured heads and also their \yavc numbers in vacuo. The r', t" - values assigned to each band and the type to which its double-heads belong, are also included in the table.As the Q“form heads are ver} close to the origins, it may be considered that their wave numbers would represent very ai)proximately the positions of the res]^eclive- band origins. Henc e using the wave minibcr data of the Q-hcads, the following equations have been iiuiependcntiy derived for the (u) and (6) stib- systeiiis in the usual w^ ay.Kdr the 6-siib-systein''” 374^ 1^ 5-7 + ( r '+ i ) - 5 .S o  (';•'+i)* “ 817.0 (i’" H-i) + 5. jo ^and for the a-sub-systemv =  30707.7 + 879 .0  { v '  ^  i ) -  s s ) 0  ( r ' 4* i ) ‘^  817.5  ( r 'M - i ) ' l-5 .J0Jn table II are given tlie differences between observed and computed wave- numbers of the band heads.As the values of uj',. and (o'L do not differ very ccmsiderably, the intensity distribution of the bands w^ ould He on a relatively narrow Condon i)arabola in accordance with the Frank-Condon theory. Although no actual measurement of intensity w^ as made, a visual estimate seems to support the above view, It is further noticed that the Condon parabola in this case has one limb very short while the other limb is comparatively long.C O R R E L A T I O N  O F  T H E  B A N  T)  S Y S  T  K  M  SIt may be noted at the very outset that since SbO is an odd molecule, its electronic states should be of even multiplicities. The vibrational analysis shows that as one would norimilly expect, only doublet electronic states are involved in the emission of three observed band systems. The data of their v ,^ w,, and WgAtf values are collected together in Table 111.216 A. k . Sten GupiaVm ,K  I .AI n  a i r .2452.512453.792455.32245f>93 245^'25 2.159.59249.3.322504.62 2506,05 250H.142509 52 2511.So 2513.19 2542.042544.172545.34 2546.S32548.632554.962559.522560.892563,842565.212596.97 2600.302601.57 2603.70 2605.402606.582611.89In vacno. in cm ■ '40762.24 0 7 4 0 . 940715.6 4068K.1)40667.0 4< 164 5 . ' '  401195.13 9 9 1 4 . 239891.439858.23 9 8 3 6 . 439798.7 39778-1 .39326,739293.639275.73 9 2 5 2 . 739225.039127.5 39058 13 9 0 3 7 . 238992.3 .38971.538494.93 8 4 4 5 . 63 8 4 2 6 . 9  3 8 3 9 5 - 43 8 3 7 0 . 4  3 8 3 5 3 03 8 2 7 5 . 0j A s s i g n m c n t .! a (3. 2)ji1 1)«(j, 1)j t l ( j , o )I tifi, !■)oja(2, 2)a(2j 2)a ( i ,  J)1)0)0 (4, -2) ^(3, I)b{2, o) b(2, o)0(2, 3)u(i, 2 ) (id, fl(o, j) « ( o ,  i )  <’ (3,?)(2, l) b(2f j)b i h  0) l>(i, 0) * a(a, 4) fl(i. 3)Type of I je a dO P !J P  nV ()(JV o  p5Io o P  o P0 opQPnQPQPQ0kair3617.602618.902651.20 2655.365656.952659.592661.052663.96 2665.932666.142667.08 2672 642711.90 2717. JO 2721.752722.442724.012729.222776.66 2778 16 2782,782754.15 2830.42 2831 50 2837.502838.66 2845.002846.09 2900 242909.20uTil v a c u o ,  i n  ctti  ^ ‘ .A a a i g n m e n t ,T ^ o fn e a d .3 8 1 9 1 . 5 fl (o , a) ■ Q3 8 1 7 2  6 a ( o ,  a) r3 7 7 0 7 . 6 6 (3 . 3 ' , U3 7 6 4 8 . 5 ■ 6 ( 2 ,  a) 03 7 6 5 6 , 0 h'.z, 2) p3 7 5 8 8 . 7 6 U ,  1 ) 03 7 5 6 8 . 0 6 ( 1 ,  1 )  , ' p37 S-’ 6 .9 6 ( 0 ,  0) 03 7 5 0 4 . 8 b ( o ,  0) p.I7496..3 f ( i ,  4) u3 7 4 8 3  " f l ( r , 4 ) p3 7 4 "5  1 <1(0, 3 ) f j3 6 8 6 3 . 6 6 ( 2 ,  3 ) 03 6 7 9 3 . 1 6 ( 1 ,  a) 03 6 7 3 0 . 2 <1(1, 5 )  ^ Q3 6 7 2 0 . 9 6 ( 0 ,  1) 03 6 6 9 9 , 7 6 ( 0 ,  i ) p3 6 6 2 9 . 7 u l o ,  4) n3 6 0 0 3  9 6 ( 1 ,  3 ) 03 5 9 8 4 -4 6 ( 1 ,  3> P3 . 5 9 2 4 . 7 6 (o', a) y3 5 9 0 7 . 0 6 ( 0 ,  a) P3 =3 20 .1 6 (a, s) Q3 5 3 0 6 . 6 6(!?, 5) P3 5 2 3 1  9 ~  6 ( 1 ,  4) y3 5 2 1 7 . 6 6 ( i ,  4 ) V3 5 1 3 9 - 1 b fo ,  3 ) “ Q3 5 1 2 5  6 6 ( 0 ,  3 ) p3 4 4 6 9 - 8 6 u ,  5) Q3 4 3 6 3 - 7 6 ( 0 ,  4) QNew Vltra^Violei Band System of Antimony Monoxide 219T a)h.u II.Band.a(o, 4) Mo. 4) ai l ,  5) '’ (i, 5)fl(o, 3) I’ lii, 3) «(r, 41 M i , 4) />(2, .si 0 (0 , a)o('i<>(i, 3)Hantl. O—C in cm *. liaml O -C in  enr ‘<"(a, 4) -1 .6 2)rt(o, 1) 4 - 1 . 41-"J,2h{o, 1) 0(1, o) ; -hr.Sa(i ,  2) 1, 0) 1 0.0hi i .  2) 4-0,5 <1(2, i) ! 42.1in(2. 3) -5.0 >^(2, r- ! n.t)1I’ la. 3) n.o <>(3. 2) j 'hj Ha(n. i.| H-o.; b(:\, 2^ 1 4 0 3h(ij, n) 1 ™ 0.1 bl2, 0) -1 - 0  s0 ( 1 , 1' ; 4-0.r 1) 4-3-0h (M ) ! *0 I ?>(4. - '1,50(2, 2) 11i- n.6 >^(3, 0) - 2 . 3T abi.k III-DiUd of Shi') hand svsicws.IVsigimtirm t f Ijand svsieni. 1iV, 1 w /iw. '.T,' w / ^ ff ftWA . ! Region of occurreneeLess Refrangible. R 20667.5 ,18528 5 : 569.0i5.00 817.2 ,S-38 ; A6650-A.450D11More Refrangible R 26594.024322.01582.0 6.50 817 0 5 -4 t^ 1 A4720 <^ .3245jNew ultra-violet. V 39767*73 7 4 9 5 -7879.0R8 q 5S.90580817-5817.055 201j A29I0-A2450The near equality o f w , " -  and w / '. v / '-  values indicate that all the three systems have a common lower level. It is further evident that each of the more refrangible and the new ultra-violet systems ha.s a doublet spacing of the same magnitude. One is therefore led to infer tliat this spacing must be bel\Aeen the doublet components of their common lower level since it is veiy uulikely that both of them have the s^me doublet separation in their upper states. The large value of the spacing suggests further that this common lower level is a * 1 1  state, It may be noted here that jn each of the hopiolr>gous molecules NO» PO220 A, K. Sen Guptaand As(J, the band systems so far discovered have also a common lovi^ er level, which is considered to Ijc the ground state of the molecule concerned. In the present case, the common lower level of the band systems may therefore be suppo.scd to represent the ground state of SbO and an interval of 2272 e n r '  between its two 1 1-components seems also to be of the right order of magnitude.It is, however, probable that the doublet sejiarations in the upper levels of the above two band systems are too small to be measurable. In that case these upper levels are either or Most likely each of them is a state.The presence of a fairly strong Q-head lends support to this view'. It is there­fore not unreasonable to su])pose that the more refrangible and the new ultra­violet systems are due to Iransilions between two difierent excited statesto a common II ground state. On the other hand, the less refrangible system has an haterval of only 2139 cm“  ^ between its tw'o sub-systems. This interval is less than that for each of the other tw'o systems by 1330111“ .^ It seems therefore probable that the upper level of these bands has a doublet separation of this value. The absence of double heads as well as the magnitude of the separation suggest further that it is very likely a ' .^fl state. Hence the less refrangible system may be assigned to the transition ^ 11—>-‘■ *,11.-113 3 cm I:-Ic .-a‘ z-c®i:F j (i. 1.The electronic transitions concerned in the emission of the three observed band systems of SbO may be diagiamitically represented as shown in Fig. i .It is next of interest to ascertain their analogous band systems in the spectra of the homologous molecules. ""H o ]\i o I., o n n v s  s r u  C 'i' r  a ■. Anumgst the homologous monoxides of group V (b, elements, it is w'ell known that NO (Jevons, 1932), which forms the first member of the series, has four overlapping baud systems designated as y, (i, 8 and e bands and lying in the regions A1665-A3400, A_>r85-A527o, Aigoo —A2300, and A1670—Aj88o, respectively. The first three systems appear in the emission, spectrum of the molecule. All of them have, however, a common lower level which is the ground state of the molecule. Excepting the bands of the /8 system, thosie ofNew Ultra-Violet Bend System oj Antimony Monoxide 22!others are degraded to the violet. From an analysis of their rotational strurtntc,7-bauds have been assigned to a transition while /J-baiids toIt is further supposed that 8-bands arc also due to a transition. Thenature of the upper stale of the weak t-bands^ which have been observed in absorption only, is still undecided. The doublet spacing of the two IFcomponents of the ground level of the molecule has a value of 12 1 .In the spectrum of PO, (Ghosh ct a/, 1Q31, Sengupta et a/, 1939), far only two band systems are known. One of them lies in the region A2280--A27Q0 and is considered as analogous to >-bands of NO, The second sy.slein lies at A3300 and is supposed to be an analogue of /3-bands although it lies on the longer w^ave-lengtli side of the first system. As one would cxpect> the doublet separa­tion in the ground level has a higher value than that of NO^ and is 224 cm**'.Two systems of bands with a common lowxn* level liave been recently analysed by Connelly (1934) and others (Jenkins ctal, i935i ^Morgan c/a/, 1935) ill the spectrum of AsO. They are designated ns A  and B systems and lie in the regions A295o-A3^5o and A23S0-A2800 resI)ectivcl3^ The A system degrades towards the red while the B system towards the violet. Kacb of llieiii ('onsists of double headed bands and has been assigned to a 1 transition thenground level having a separation of 1026 c n r \  between the ll-components. In fact, the A system shows none of the characteristics of a " 'll— ‘""11 transition. Jenkins and vStrait (1033) arc* of opinion that it is the analogue not of the A*-bands but of the 8-bands of NO while the B system is analogous to the 7d)ands. It is thus evident lluit wdiilc in the case of NO the 8-baiids He on llu* shortei w^avelength side of the y-bands, the order is veveresed in the si»ec tiimi of A s ( ).In the spectrum of SbO, the general appearance and intensity ilisiribution of the more refrangible system resemble closely those of A sy>leii, of AsO. it is therefore vci'c likely analogous to the 8-bands of NtJ,  On the olhei hand the new ultra-violet baud system appears to be an analogue of the ydiands, since it occurs in the expected region of the spectrum. It may Ijc noted here that for the two sub-systems of the y-bands of NO shifts from 439^5 tuid 43^44 cm "C to 40489 and 40265 cly^^ for PO and to 404i i  and 39.^87 cm‘"'for AsO. In the spectrum of SbO, iv for the new ultra-violet bands is at 3976S and 3747  ^ , It is, however, significant that this system becomes weaker in intensity with increasing molecular weight of its emitter. In fact, it is so w'eakly developed in the spectrum of SbO that one may be led to picdict its absence in the spectrum of BiO under similai conditions of excitation. It is further found that the more refrangible and the new ultra-violet systems of SbO aie more similar to the A  and B systems of AsO than to the 8 and y bands of NO as regards their intensity distribution and position. The less refrangible system of SbO is very likely analogous to the /3-bands of NO since it bears a dose resemblance to the latter in its intensity distribution, besides being due to a sijnilar transition.A correct vibrational analysis of the bands of BiO is still wanting to make the analogy complete.5--1455P- IV222A C K N O W L E D G M K N Ti4, K. Sen GuptaThe author desires to offer his Iwsl thanks to Prof. P. N. Ghosh for continual interest and encouragement in the course of the investigation and to Dr. P. C, Mahanti for many helpful discussions.R E F E R E N C E SConnelly, F. C., 1934, Prof. Phys. Soc., 46, 790.Ghosb, r. N. and Ballt G, N., 1931, Z, /. Phys., 71, 362. Jenkins, F. A , and Strait, L A>, 1935, Pliys. F hk 47, 136. Jevons, W., Report on Band Spectra of Dialomic Molecules. Morgan, F., and Shawhan, E- N-, 1935, Phys, Rev. 47, 192 Sen Gupta, A. K., 1935, Pror.  Phys.  Soc.,  47, 247.Sea Gupta, A. K., 1939, hui.  Jour.  Phys.,  18, Tzjc;.

A New Ultra-Violet Band System of Antimony Monoxide (SbO)

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A New Ultra-Violet Band System of Antimony Monoxide (SbO)

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