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Perturbations and rotational intensities observed in CN bands emitted by reactions of organic molecules with nitrogen atoms
JOURNAL
OE‘ MOLE(‘ULAH
SPE(‘TROS(‘OPY
7,
104-208(1001)
Perturbations and Rotational Bands Emitted by Reactions Nitrogen K. H. KIEGS AND .\‘alional
Bureau
Intensities Observed in CN of Organic Molecules with Atoms H. 1’. BROIDA
of Standards,
Il’ashinyton,
I). C.
The rotational perturbations between the v = Olevel of t,he LPz+ electronic state and the 2) = 10 level of t,he .491, electronic state of CN have been re-iI)vest.igat.ed. CN in the B% and .,tW st,at.es was produced by the react.ion of organic molecules with the nitrogen afterglow. Itotjational analyses of the 10, 3 and 10,5 bands of the =I% - S*Z system and of the 0,O band of the B% - XV5 system have been made. From t.he wavelength measurements the pert.urbed wave functions have been determined in terms of the unpert,urbed wave funct,ions. The relative intensities of the perturbed lines, extra lines, and neighboring unperturbed lines have been studied as a function of pressure from 0.1 to 100 mm Hg. A new pair of extra lines has been found. At the higher pressures the populat.ions of the excited rot.at,ional levels of CN approach a Boltzmann distribution. As the pressure is lowered the intensities of the perturbed and ext,ra lines become continuously more anomalous. In the 12-s bands no extra lines were found and the perturbed lines become weak, while in the 13-5 band the unpert,urbed lines are attenuated most and t,he ext.ra lines are attenuated least. The interpretation is given t,hat, CN is formed in the :1% state more than 20 t.imes as readily as it, is formed in the B 5 &ate in reactions of organic molecules with the nitrogen aft,erglow. 1NTKOI)UCTION
The CN molecule has been the subject of many spectroscopic investigations. It,s two he&known rlrct.ronic transit,ions arc the B2~+-1X2~’ (violet,) syst,em and t,he A‘?I-S%+ (red) system. Inteusit,y anomalies in the B-X system were first observed by Hcrzberg (1). He found that) on exaitat,ion by “uctiv(* nitrogen” certain corresponding lines of the 0 ,O and 0,l bands were enhanced. In t,his met,hod of excitation, first used by Strut’t and Fowler (.22,, organic gasps or vapors, such as acet.ylene or chloroform, are introduced into t.hc nit,rogen afterglow. The result is a flame-like rcact,ion, whose radiations belong almost entirely to t,hr ‘4 -X and R-X elect,ronic: transit#ions of CN. Byck (3) demonstrat,ed that. as the pressure increases t.he enhanced lines approach normal intensity. Beut#ler and E’red (4) and Wager (5, 6) showed that’ a system of rota194
PERTURBATIOSS
IS
CS BAN’JM
19.7
19724.49
47.18
34.19
17 l/2
43.68
58.29
68.31
585.10
86.74
696.70
48.91 41.94
698.10
55.31 09.58
20.68(P)
06.12
60.92
01.19
16 y'2
72.30
59.53
15 1/2
65.96
40.62 30.82
70.40
74.09
77.22
79.54
49.74
5E.36
66.33
74.09
55.83
64.22
72.08
79.54
86.02
92.3-l
79'7.61
02.54
06.99 (P)
43.63 10.60 81.35
m.97
4.76
85.75
71.24
14 l/2
22.69
30.07
36.82
G2.85
48.24
52.99
43.24
UC.08 82.37
42.40 16.77
82.73(~1
26.31
30.44
37.24
39.74
41.60
42.94
43.63
40.96
18.90
38.90
36.30
21.65
82.37
33.00
22.12
20.48
29.26
19825.17
22.12
19821.65
R2
81.35
87.29
93.10
60.32 56.99
798.39
63.06
16.29
31.00
698.32
82.33
13 l/2
45.05
692.72
I2 I./2
10.79
58.29
22.69(P)
83.U
02.43
wt.22
19.82
9 li2
694.58
l.l1/2
54.39
27.66 (P)
e 1/2
05.20
71.24
63.77
34.62
7 l/2
15.32
33.67
72.76
40.99
6 1/2
Il.48
81.35
46.68
5 Y2
10 l/2
89.06
51.55
4 l/2
03.17
79.54
07.30
64.33(PI
796.46
55.83
3 3.G 65.02
77.22
10.99
19803.17
74.09
19770.40
66.9
1
l4.08
19816.77
10, 3 Band Wavenumbers 19792.34 cm-’
2 I./2
=
19766.go
19759.46
0p12
V 0
A2B - ?x
w
lj2
p2
CN
TABLE I
F
; w 2
5
g
E
$
II
12.82
44.04
25.34
06.17
06.21
591.39
75.81
59.51
42.71
25.34
07.40
19 Y2
20 l/2
21 l/2
22 l/2
23 l/2
24 1/2
25 1/2
12
75.32
01.19
35.19 17.60 499.39
28 l/2
29 l/2
30 l/2
75.21 57.87 39.65 20.99
77.38 60.88 44.O4 26.10
31 l/2
32 li2
33 l/2
34 Y2
08.34
08.34
591.57
23.91
38.79 23.09
37.10
53.05
67.10
80.18
692.72
04.75
16.12
26.85
37.12
46.68
R2
593.35
495.13
JJG.43
32.99
50.98
52.11
27 1/2
50.42
63.20
86.74
16.86
585.10
697.45
07.72
17.23
26.14
34.49
R1
31.85
46.30
60.18
73.44
86.02
Q2
68.31
84.03
599.19
13.53
27.35
40.46
53.05
64.91
76.14
Q,
68.31
495.50
14.72
33.21
51.15
OP
continued
26 l/2
62.13
79.49
596.46
28.63
p2
20.56
Pl
18 l/2
J
TABLE I
SR21
16.77
05.47
793.68
797.75
88.26
78.24
67.57
56.36
44.52
x2 112
13 l/i
u 1/Q
15 l/2
16 1/2
17 Y2
55.35
68.59
81.41
27.57(P)
06.63
47.69
22.60
91/2
Il.1/2
57.04
29.86(~1
8 1/2
37.88
65.92
36.19
7 Y2
UC.91
74.31
42.06
6Y2
10 l/2
82.29
47.30
5 1/2
24.27
37.99
5l.ab
63.53
75.38
797.10
05.88
09.74
19.94
29.93 (P)
38.90
21.69 ~06
47.60
55.77
63.47
28.72
35.18
41.04
70.67
77.40
51.00 46.32
83.63
55.0s
797.30 86.75
89.39
94.67
899.47
58.55
61.43
63.67
07.39
16.76
15825.67
81.71
03.81
65.31
89.72
51.91
4 u2
79.74
07.68
66.28 (p)
896.76
55.91
3Y2
Il.10
15903.26
15659.30
52.35
58.11,
63.37
67.96
72.00
75.47
78.34
60.62
82.29
67.46
74.62
81.26
87.39
93.00
898.09
02.71
06.80
10.42 (PI
13.53
16.16
83.88 83.40
LB.32
31.98
35.61
38.65
43.22
44.83
45.81
46.21
46.21
45.81
43.43 44.83
41.52
39.13
21.20 19.99
36.22
15932.94
29.87
21.92
22.16
83.88(~1
83.O7
77.16
73.93
66.73
15921.20
15670.01 21.92
R2
R1
2 1/2
Q2
l4.02
Ql 15866.51
0P12
13-h
p2
0
TABLE II X2= 10, 5 Band Wavenumbers v = 15891.94 cm-’
15916.54
p1
A’r-
Y2
J
II
CN
E
i? u
z E g
00
;;
47.89
30.51
691.64
77.01
61.80
46.05
29.71
12.W
595.53
77.31
21 l/2
22 l/2
23 1/‘2
24 W
25 l/2
26 l/2
27 l/2
26 l/2
29 l/2
64.79
05.73
20 l/2
75.m
594.12
12.57
81.17
697.00
12.38
27.15
19.24
l/2
I?
2
41.60
P
32.17
pl
18 l/2
0, J OP 12
ii
47.63
43.26
78.31
692.73
06.57
19.83
32.58
44.72
56.36
67.39
77.85
87.77
Q,
TABLE
46.93
63.26
79.12
694.53
09.44
23.78
37.80
51.04
63.77
75.99
87.77
799.01
Q2
continued 1
63.35
74.79
85.63
795.95
05.69
UC.91
23.52
31.59
39.08
46.01
R
2
79.48
791.39
02.74
13.56
23.88
33.65
42.90
51.60
59.79
R
27.96
200
KIESH ANI) BROII1.4
used to maint,ain t,he disctharge at pressures shove 2f, mm and a l2f,-watt. pot%e1 supply was suffiicient~ for lower pressures. Spect,ra were recorded both phot.ographicAally and photoelectrically. l’hotographic spect,ra were t.akcn at the ?r’at,ional Bureau of Standards by rising a :‘O,OOOlines-per-inch grat,ing in a Wadsworth mounting, and at t.he Johns Hopkins University by using a 30,000 lines-per-inch grating in a I’swhen-ltlmge molmt,ing. The NBS grat.ing was Ilsed in the first. order for t,he A-X 10,X band with a head at r>04-8.1B8 A. The JHU grat.ing lx-as llsed in t.he first, order for t,he LI-.Y 10,s band wit.h a head at, 6278.831 A and in t.he second order for the B-5 0,O Ixmd. Exposure times did not exceed two horwu. Wavelength measurements were made by comparison u ith interferometrically-r~le~ls~lred iron and neon lines of the hollow-cat,hodc diwhargt (12) and were convcrt.ed to wave nrunbers by means of the new “Table of Wavenwnhers 2000 A to 7000 A” (13). I’hot.oelectric, spcct.ra were recorded at, ?JRS t)y using a 30,000 lines-per-inch grating which was mounted in t,he Ebcrt. system as dcswitw~l by Fast,ie (1.j). ENERGY
LEVEL
ANALYSIS
The work of Jenkins et al. ( 15) was used as a guide in the analysis of t,ht ;t -S 10,:s and IO.5 hands. The 10,4 hand has been analyzed by Wager (5). The measured wavenumbers of t,he lines are given in Tables I alld II; the rot.at.ional constants are given in Tahlr V. The follon ing perturbed lines were ohserved and found t,o he free of blends: Rl((i,$i), P1(S.l~), Rs(l)j,i), and&( 15!,2) in the 10,s band; C&(332), Rz(9,1$), and Pr(ll$,~) in t,hc IO,,5 hand; other perturbed lines iiere l)lends. No ext.ra lines were observed. The sttalysis of the B-X 0 ,O halltl was facilitated by the effect. of pressure on line intensities. Ngurc I shows the I’ bratlches at. pressures of 1:5 and O.-l mm Hg. The vanishing at low prcswrc of one of the compownts of the doublets in t,hc
a
3;
J’
7;
8;
b
b ,
, 3075:77p.
3883:Ol
A
FIG. 1. The P twanches of t,he l?.~-S*2 0,O band; (a) p = 0.1 mm Hg and (1)) p = 15 mm Hg. The perturbed and extra lines we indicated and the values of J’ are given.
I’ERTURRATIO?U’S
201
IN CN BANI )S
vicinity of the .I’ = 15$ pwt,urhation provides a helpful clue in the analysis. Sclwt ion rules r’qttirc’ that the branches perturbed in t,his region be t,he I’, and RI brunches; comparison of wave number shifts with those observed in the .+S battds idrntifics thr low-prcssuw lines in t.he vicinity of’ t,he J = l.Tf.2 p~~rturbatiott as I>, and RI lines. The cxpwimcntal resolving power was about 300,000; ronscqrtcnt~ly t,he high-pressurr lines ntarcr thr band origin were inc~omplctvly tvsolvc~d. The low-pressurr lines wcrp sharp, howcvrr, and assignmvttt to thr PI and K1 bratwhcs yielded a consistent~ analysis. Comparison of low and high-pressure measurements yielded good wtimatcs of the wavenumIwrs of thcl P2 and K, lines whcrc they mcrt~ not cwmpktely resolved from thra I’, attd II’, littw. A tww pair of extra lines \vas found, cwwsponding t,o the wwk itttwwtiott of the upper levels of the lines with J’ = 81,~. The measured wavc~tttttttbc~rs of thcl linw arc’ given in Tables III and II’; the rotational constant,s arc gi\wr itt T~tl~If~I-.
h-”
2 :i
s IO II I’ I :j II I5 Iii I7 1S I!1 20 “1 22 2.‘1 24 25
p,
25793.99 90.33 X6.80 83.44 x0.23 ii.11 74.14 71.23 6X .Mi
I’,
25X01 .W 05.74
(,y)
(Xi,09 63 (is
32.10 %I.ti2 49.2!) 48.10 25747.03 4ci.14 45.X 44.73 44.25
25790.33 X6.80 w .44 MO.23 (p, ii.11 74.14 il .2!J tis.ti4 tx 05 ti3. (i0
(i1.2!) (1’1
(il.38 ii!) .24 57.23 55.34 53.36
K,
(p,
,511 14 57.1:s 55.24 53.51 51 .uo 50.44 49. IO 47.91 2.571G.S(i 45.95 45. Iti 44, ,3io 44.01
(19.92 14.27 IX.71 “3 ,32 L’i.!17 (1)) :32. $1; :1i. Wi 13 .O!) 4x, 35 5x. iti 59,%!) (il.94 i0.48 (11) Tti 70 S% 74 sx 92 !15,24 901 .w 0X.28 25915.00 21.x2 L’x ?(3
K,
25X05.74 09.92 14.27 (1’1 1X.71 23 .32
2s 03 32.w
37 I!” 13.03 48.25 (1’1 53.63 59.17 6-l X3 70, tit) iti. 52 x2 .55 8X.74 95.04 no1 .49 ox .07 25914. TN
21.wu “x.(il
202
KIESH
ANI) TABI,b;
CA: AW
.Y*Z IO,0 BAND WAVENUMBERS
BROII)A IV
(appearing
asextra
lines in the @Z-X’%
0,O Band)
K” 3 5 6
25813.92 25779.89 25828.91 27.64
7 8
25772.17 63 .33
9
10 12 14 16
25849.50 25762.55 25871 .TG 25754.65
8,. I),,
1 .8923 -7.31 x 10-6
1.837 -5.3 x
1 .X1)29 10-G -6.01 x IO-”
I .5303 -4.71 x
I.9598 10-G -6.11 x
IO-6
-51.12
A
The square of t*he wave-fmlction-mixing coefhcientj is given by pe = c/A, where E is the energy level shift, and A is t,he actual separat,ion of t,he pair of int,eract,ing levels (6). The values of t are t,he wave numhrr shift,s of t,he perturbed lines and the values of A are the wave numher differences lwt,\vecn corrcsponding perturbed and ext,ra lines. Figure 2 is a schematic energy level diagram using t,he perturbat,ion with J = 1r’s 1, as an rxamplr. Values of E, A, and p2 are given in Tahle VI for all pcrturhat.ions uhcrc ext,ra lines were olwrvrd. These values are prohuhly more accurate t,han t.hose repart.ed by Wager i/i) l)etcausc of t,he use of low pressure t-o at,tenuate t,he mlperturbed lines and because t,hc A-X 10,3 and 10 ,.’ hands are not significantly overlapped by ot,her hands. Relative t#ransition probabilities ohtained from t,hese newly measured values are in het,tcr agrccmentj than t#hosc of Wager with the rrlativc transition prohahilit,ies measured from relat,ive intensity measurements (IO). LINE
INTENSITIES
A photoelectric tracing of the -4-X lo,:3 hand at a pressure of 1.0 mm Hg is givrn in Fig. 3. The perturhed lines RI ((;!,a), P,(Sli), R,(9>$), and Q2( 151,.;), indicated hy arrows, are free of Mends. Figure -I shows t,hc region of P,(8j2) and Q2( 1.‘; 2) at pressures :< and 0.3 mm. The pert,urhed lines are weaker than
t’BRTI!RBATIONS
IN
EXTRA
(‘N
B.4IYI)S
LINES
-
7
-J
-
15;
IO
15:
0
V
I a
-
1
-I-
-
I I
1QIZ
Q2
I I I I I I I I I I I
P2l
I
P,
RI
-i-
X2X+ RED
15i
SYSTEM
-
-
x 2r+ L VIOLET
SYSTEM
16+
-
‘56
-
149
201
FIG. 3. Photoelectric cnt,e perturbed lines.
KIF:SS ANI) BROII)A
trwing
of the .-l*lI-S*Z 10, 3 Imnd :tt p = 1.0 nun Hg. Arrow
indi-
neighboring lines of the same branch, espcrially at, p = 0.3 mm. Table VII gives the rat.ios of t.he inknsities of the branch envelopes at t,he points of perturhat,ion t,o t,he intensities of t,hc pcrturhed lines for various pressures. This ratio increases wit,h decreasing pressure and is not, t,he same for each pertjurhat.ion. As t,hc presstwe increascn this rat’io appears to approach unit,y. The effect, of pressure on relative intensities in t#hc 13-X 0,O band ia much great,er t,han in the A-X syskm and is discussed in d&ail in Ref. 10. The fact t,hat, at, pressures war 0.1 mm the cxt,ra lines are the strongest lines leads one to spccnlatJe about t’hr rclat.ive rat.es of formatjion of CN in thr ‘4% and B’S elcct.ronic st.atos. The energy lcvols are populat.ed inibally by an ~mknown mrchanism. l’opulat,ion of some levels and depopulation of others rrsults from c~ollisions of CK molecules with t,he various speck prrsrnt. lkpopulation of cxrikd levels also rrsulb from spontanrow emission. At, high presslwr many collisions occur before emission and the line-intensity distribution indicates t#hr smootJh population dist~ril)ut~ion which thr collisions have rst~al~lished ( 9). At low pressure relat,ively frm collisions occur heforr radia.tion and the line int,rnsities are indicative of t,he relative rat)cs of formation of rxrit,ed CN in thr various levels. Comparison of lint intrnsit,ies ill t,hr vkinit~y of the J = I:!,6 prrturhation givrs t.hs brst rst,imatr of thr rclat.ivr rates of formation of Clj in the A% and Bk elertjronic st.ates, insofar as this ronwpt has meaning. J,rt’ IIS IISC at p = 0.10
P=
0.3mm
c 17;
104
P= 3.Omm
3 5d7d
5065
A
206
KIESS
P (mm Hg) 0.3 1.0 3.0 14.0
Q,(3’$) 1.6 1.5 1.5
P,B’i)
AND
RROIDA
&(6’5)
1.5 1 .:< 1.2 1.2
R,(Y’h) 1.1 1.1 1.1 1.1
1.8 1.4 1.1 1 .:3
Qz(lS’i) 2.5 1 .9 1.6 1.1
state. The intensit’y II5 of the perturbed line is probably considerably nffeckd by collixiomal kansfcr between the p&urhing lrvcls (IO), which are about 1.X cm-’ apart, hut] the sum IB + I,, should be lit,tlc aticrt,ed by collisions because the nearest rot,ational lrvcls of t,hc R”?; state arc ahout 60 cm-’ away. The levels nearest the upper stat,es of the two lines on either side of the perkhation are the slightly perturbing levels of the L4”~ st)at,e; t,he nearest of these is about, 10 cm-’ from it#s nearest neighbor in the B” Z state, so that the inknsitics I14 + I16 should not be much affectred by collisions at, p = 0.10 mm. In the preceding we have not considered thr unpert~urbed doublet, components of t,he R”?: st,ate; however, the virtual absence at low pressures of lines from t,hcsc levels indicat#es that collisional transfer to these levels is relat’ively improbable at low pressures. Let us assume that) at p = 0.10 mm c,ollisional t,ransfer is important only I+ t,ween strongly interact’ing levels and that t,he inknsity of a linr whose initial level is a mixed stat,e is proportional t,o the product, of thr pate of formation Fa of CN in the ilk stat,e and the percent’age of ii”11 in t,he mixed state plus the product of t,he rate of formation F, of CN in the H2S state and t,he percent,age of B2Z in the mixed stak. Then I, + I,, and I,, + I16 are unaffected hy collisional kansfer and WC can writp:
116+ IE 41s = IX
FAp;6 + P,(l = FApf., + F,Jl
-
P:,, + F,(l
-
p&j + F.t~:e
+
~46) + FB $5 FBO
-
P%
as the mixing coefficients p14and p16are very small. Estimat,ion of gIs at, pressures near 0.10 mm shows that FA/Fs is greater than 20 (and perhaps as large as lp50). To t#he extent that collisional transfer is important, bet,wcen levels othrr t#han the strongly interacting pairs, this estimat,e is a lower limit, for the rat,io F,/F, of the relative rat,es of formation of CS in t#he A% and B”S electronic states. EstimaGon of FA/‘Fs from the intensity rat,ios $ and g4 at the other point,s of strong interaction yields smaller values, as would be expected since the wavefunction mixing is smaller and the rotational levels are more closely spaced.
208
KIESS
AND
BROIDA
5. A. T. WAGER, Phys. Rev. 61, 107 (1942). 6’. A. T. WAGER, Phys. Rev. 94, 18 (1943). 7. G. H. DIEKE, Phys. Rev. 47, 870 (1935). 8. G. HERZBERG AND J. G. PHILLIPS, Astrophys. J. 106, 163 (1948). 9. N. H. KIESS AND H. P. BROIDA, in “Seventh Bymposium (International) on Com bustion,” p. 207. Butterworth’s Scientific Publications, London, 1959. 10. H. P. BR~IDA AND S. GOLDEN, (‘an. J. Chew. 33, 1666 (1960). 11. Y. TANAKA, A. JURSA, AND F. LEBLANC. in “Threshold of Space,” !M. Zelikofl’, ed.) p 89. Pergamon Press, London, 1957. 12. “American Institute of Physics Handbook.” McGraw-Hill, New York, 1957. 19. “Table of Wavenumbers 2OCQA t.o 7000 A,” U. S. Ijepartment of Conummr, N:t!ionttl Bureau of Standards Monograph 3, Washington, 1). C., 1960. 14. W. G. FASTIE, J. Opt. Sot. dtn. 42, 641 (1952). 15. F. A. JENKINS, Y. K. ROOTS, AND R. S. M~~LLIKEN, Phys. Rev. 39, 16 r.1932).
OE‘ MOLE(‘ULAH
SPE(‘TROS(‘OPY
7,
104-208(1001)
Perturbations and Rotational Bands Emitted by Reactions Nitrogen K. H. KIEGS AND .\‘alional
Bureau
Intensities Observed in CN of Organic Molecules with Atoms H. 1’. BROIDA
of Standards,
Il’ashinyton,
I). C.
The rotational perturbations between the v = Olevel of t,he LPz+ electronic state and the 2) = 10 level of t,he .491, electronic state of CN have been re-iI)vest.igat.ed. CN in the B% and .,tW st,at.es was produced by the react.ion of organic molecules with the nitrogen afterglow. Itotjational analyses of the 10, 3 and 10,5 bands of the =I% - S*Z system and of the 0,O band of the B% - XV5 system have been made. From t.he wavelength measurements the pert.urbed wave functions have been determined in terms of the unpert,urbed wave funct,ions. The relative intensities of the perturbed lines, extra lines, and neighboring unperturbed lines have been studied as a function of pressure from 0.1 to 100 mm Hg. A new pair of extra lines has been found. At the higher pressures the populat.ions of the excited rot.at,ional levels of CN approach a Boltzmann distribution. As the pressure is lowered the intensities of the perturbed and ext,ra lines become continuously more anomalous. In the 12-s bands no extra lines were found and the perturbed lines become weak, while in the 13-5 band the unpert,urbed lines are attenuated most and t,he ext.ra lines are attenuated least. The interpretation is given t,hat, CN is formed in the :1% state more than 20 t.imes as readily as it, is formed in the B 5 &ate in reactions of organic molecules with the nitrogen aft,erglow. 1NTKOI)UCTION
The CN molecule has been the subject of many spectroscopic investigations. It,s two he&known rlrct.ronic transit,ions arc the B2~+-1X2~’ (violet,) syst,em and t,he A‘?I-S%+ (red) system. Inteusit,y anomalies in the B-X system were first observed by Hcrzberg (1). He found that) on exaitat,ion by “uctiv(* nitrogen” certain corresponding lines of the 0 ,O and 0,l bands were enhanced. In t,his met,hod of excitation, first used by Strut’t and Fowler (.22,, organic gasps or vapors, such as acet.ylene or chloroform, are introduced into t.hc nit,rogen afterglow. The result is a flame-like rcact,ion, whose radiations belong almost entirely to t,hr ‘4 -X and R-X elect,ronic: transit#ions of CN. Byck (3) demonstrat,ed that. as the pressure increases t.he enhanced lines approach normal intensity. Beut#ler and E’red (4) and Wager (5, 6) showed that’ a system of rota194
PERTURBATIOSS
IS
CS BAN’JM
19.7
19724.49
47.18
34.19
17 l/2
43.68
58.29
68.31
585.10
86.74
696.70
48.91 41.94
698.10
55.31 09.58
20.68(P)
06.12
60.92
01.19
16 y'2
72.30
59.53
15 1/2
65.96
40.62 30.82
70.40
74.09
77.22
79.54
49.74
5E.36
66.33
74.09
55.83
64.22
72.08
79.54
86.02
92.3-l
79'7.61
02.54
06.99 (P)
43.63 10.60 81.35
m.97
4.76
85.75
71.24
14 l/2
22.69
30.07
36.82
G2.85
48.24
52.99
43.24
UC.08 82.37
42.40 16.77
82.73(~1
26.31
30.44
37.24
39.74
41.60
42.94
43.63
40.96
18.90
38.90
36.30
21.65
82.37
33.00
22.12
20.48
29.26
19825.17
22.12
19821.65
R2
81.35
87.29
93.10
60.32 56.99
798.39
63.06
16.29
31.00
698.32
82.33
13 l/2
45.05
692.72
I2 I./2
10.79
58.29
22.69(P)
83.U
02.43
wt.22
19.82
9 li2
694.58
l.l1/2
54.39
27.66 (P)
e 1/2
05.20
71.24
63.77
34.62
7 l/2
15.32
33.67
72.76
40.99
6 1/2
Il.48
81.35
46.68
5 Y2
10 l/2
89.06
51.55
4 l/2
03.17
79.54
07.30
64.33(PI
796.46
55.83
3 3.G 65.02
77.22
10.99
19803.17
74.09
19770.40
66.9
1
l4.08
19816.77
10, 3 Band Wavenumbers 19792.34 cm-’
2 I./2
=
19766.go
19759.46
0p12
V 0
A2B - ?x
w
lj2
p2
CN
TABLE I
F
; w 2
5
g
E
$
II
12.82
44.04
25.34
06.17
06.21
591.39
75.81
59.51
42.71
25.34
07.40
19 Y2
20 l/2
21 l/2
22 l/2
23 l/2
24 1/2
25 1/2
12
75.32
01.19
35.19 17.60 499.39
28 l/2
29 l/2
30 l/2
75.21 57.87 39.65 20.99
77.38 60.88 44.O4 26.10
31 l/2
32 li2
33 l/2
34 Y2
08.34
08.34
591.57
23.91
38.79 23.09
37.10
53.05
67.10
80.18
692.72
04.75
16.12
26.85
37.12
46.68
R2
593.35
495.13
JJG.43
32.99
50.98
52.11
27 1/2
50.42
63.20
86.74
16.86
585.10
697.45
07.72
17.23
26.14
34.49
R1
31.85
46.30
60.18
73.44
86.02
Q2
68.31
84.03
599.19
13.53
27.35
40.46
53.05
64.91
76.14
Q,
68.31
495.50
14.72
33.21
51.15
OP
continued
26 l/2
62.13
79.49
596.46
28.63
p2
20.56
Pl
18 l/2
J
TABLE I
SR21
16.77
05.47
793.68
797.75
88.26
78.24
67.57
56.36
44.52
x2 112
13 l/i
u 1/Q
15 l/2
16 1/2
17 Y2
55.35
68.59
81.41
27.57(P)
06.63
47.69
22.60
91/2
Il.1/2
57.04
29.86(~1
8 1/2
37.88
65.92
36.19
7 Y2
UC.91
74.31
42.06
6Y2
10 l/2
82.29
47.30
5 1/2
24.27
37.99
5l.ab
63.53
75.38
797.10
05.88
09.74
19.94
29.93 (P)
38.90
21.69 ~06
47.60
55.77
63.47
28.72
35.18
41.04
70.67
77.40
51.00 46.32
83.63
55.0s
797.30 86.75
89.39
94.67
899.47
58.55
61.43
63.67
07.39
16.76
15825.67
81.71
03.81
65.31
89.72
51.91
4 u2
79.74
07.68
66.28 (p)
896.76
55.91
3Y2
Il.10
15903.26
15659.30
52.35
58.11,
63.37
67.96
72.00
75.47
78.34
60.62
82.29
67.46
74.62
81.26
87.39
93.00
898.09
02.71
06.80
10.42 (PI
13.53
16.16
83.88 83.40
LB.32
31.98
35.61
38.65
43.22
44.83
45.81
46.21
46.21
45.81
43.43 44.83
41.52
39.13
21.20 19.99
36.22
15932.94
29.87
21.92
22.16
83.88(~1
83.O7
77.16
73.93
66.73
15921.20
15670.01 21.92
R2
R1
2 1/2
Q2
l4.02
Ql 15866.51
0P12
13-h
p2
0
TABLE II X2= 10, 5 Band Wavenumbers v = 15891.94 cm-’
15916.54
p1
A’r-
Y2
J
II
CN
E
i? u
z E g
00
;;
47.89
30.51
691.64
77.01
61.80
46.05
29.71
12.W
595.53
77.31
21 l/2
22 l/2
23 1/‘2
24 W
25 l/2
26 l/2
27 l/2
26 l/2
29 l/2
64.79
05.73
20 l/2
75.m
594.12
12.57
81.17
697.00
12.38
27.15
19.24
l/2
I?
2
41.60
P
32.17
pl
18 l/2
0, J OP 12
ii
47.63
43.26
78.31
692.73
06.57
19.83
32.58
44.72
56.36
67.39
77.85
87.77
Q,
TABLE
46.93
63.26
79.12
694.53
09.44
23.78
37.80
51.04
63.77
75.99
87.77
799.01
Q2
continued 1
63.35
74.79
85.63
795.95
05.69
UC.91
23.52
31.59
39.08
46.01
R
2
79.48
791.39
02.74
13.56
23.88
33.65
42.90
51.60
59.79
R
27.96
200
KIESH ANI) BROII1.4
used to maint,ain t,he disctharge at pressures shove 2f, mm and a l2f,-watt. pot%e1 supply was suffiicient~ for lower pressures. Spect,ra were recorded both phot.ographicAally and photoelectrically. l’hotographic spect,ra were t.akcn at the ?r’at,ional Bureau of Standards by rising a :‘O,OOOlines-per-inch grat,ing in a Wadsworth mounting, and at t.he Johns Hopkins University by using a 30,000 lines-per-inch grating in a I’swhen-ltlmge molmt,ing. The NBS grat.ing was Ilsed in the first. order for t,he A-X 10,X band with a head at r>04-8.1B8 A. The JHU grat.ing lx-as llsed in t.he first, order for t,he LI-.Y 10,s band wit.h a head at, 6278.831 A and in t.he second order for the B-5 0,O Ixmd. Exposure times did not exceed two horwu. Wavelength measurements were made by comparison u ith interferometrically-r~le~ls~lred iron and neon lines of the hollow-cat,hodc diwhargt (12) and were convcrt.ed to wave nrunbers by means of the new “Table of Wavenwnhers 2000 A to 7000 A” (13). I’hot.oelectric, spcct.ra were recorded at, ?JRS t)y using a 30,000 lines-per-inch grating which was mounted in t,he Ebcrt. system as dcswitw~l by Fast,ie (1.j). ENERGY
LEVEL
ANALYSIS
The work of Jenkins et al. ( 15) was used as a guide in the analysis of t,ht ;t -S 10,:s and IO.5 hands. The 10,4 hand has been analyzed by Wager (5). The measured wavenumbers of t,he lines are given in Tables I alld II; the rot.at.ional constants are given in Tahlr V. The follon ing perturbed lines were ohserved and found t,o he free of blends: Rl((i,$i), P1(S.l~), Rs(l)j,i), and&( 15!,2) in the 10,s band; C&(332), Rz(9,1$), and Pr(ll$,~) in t,hc IO,,5 hand; other perturbed lines iiere l)lends. No ext.ra lines were observed. The sttalysis of the B-X 0 ,O halltl was facilitated by the effect. of pressure on line intensities. Ngurc I shows the I’ bratlches at. pressures of 1:5 and O.-l mm Hg. The vanishing at low prcswrc of one of the compownts of the doublets in t,hc
a
3;
J’
7;
8;
b
b ,
, 3075:77p.
3883:Ol
A
FIG. 1. The P twanches of t,he l?.~-S*2 0,O band; (a) p = 0.1 mm Hg and (1)) p = 15 mm Hg. The perturbed and extra lines we indicated and the values of J’ are given.
I’ERTURRATIO?U’S
201
IN CN BANI )S
vicinity of the .I’ = 15$ pwt,urhation provides a helpful clue in the analysis. Sclwt ion rules r’qttirc’ that the branches perturbed in t,his region be t,he I’, and RI brunches; comparison of wave number shifts with those observed in the .+S battds idrntifics thr low-prcssuw lines in t.he vicinity of’ t,he J = l.Tf.2 p~~rturbatiott as I>, and RI lines. The cxpwimcntal resolving power was about 300,000; ronscqrtcnt~ly t,he high-pressurr lines ntarcr thr band origin were inc~omplctvly tvsolvc~d. The low-pressurr lines wcrp sharp, howcvrr, and assignmvttt to thr PI and K1 bratwhcs yielded a consistent~ analysis. Comparison of low and high-pressure measurements yielded good wtimatcs of the wavenumIwrs of thcl P2 and K, lines whcrc they mcrt~ not cwmpktely resolved from thra I’, attd II’, littw. A tww pair of extra lines \vas found, cwwsponding t,o the wwk itttwwtiott of the upper levels of the lines with J’ = 81,~. The measured wavc~tttttttbc~rs of thcl linw arc’ given in Tables III and II’; the rotational constant,s arc gi\wr itt T~tl~If~I-.
h-”
2 :i
s IO II I’ I :j II I5 Iii I7 1S I!1 20 “1 22 2.‘1 24 25
p,
25793.99 90.33 X6.80 83.44 x0.23 ii.11 74.14 71.23 6X .Mi
I’,
25X01 .W 05.74
(,y)
(Xi,09 63 (is
32.10 %I.ti2 49.2!) 48.10 25747.03 4ci.14 45.X 44.73 44.25
25790.33 X6.80 w .44 MO.23 (p, ii.11 74.14 il .2!J tis.ti4 tx 05 ti3. (i0
(i1.2!) (1’1
(il.38 ii!) .24 57.23 55.34 53.36
K,
(p,
,511 14 57.1:s 55.24 53.51 51 .uo 50.44 49. IO 47.91 2.571G.S(i 45.95 45. Iti 44, ,3io 44.01
(19.92 14.27 IX.71 “3 ,32 L’i.!17 (1)) :32. $1; :1i. Wi 13 .O!) 4x, 35 5x. iti 59,%!) (il.94 i0.48 (11) Tti 70 S% 74 sx 92 !15,24 901 .w 0X.28 25915.00 21.x2 L’x ?(3
K,
25X05.74 09.92 14.27 (1’1 1X.71 23 .32
2s 03 32.w
37 I!” 13.03 48.25 (1’1 53.63 59.17 6-l X3 70, tit) iti. 52 x2 .55 8X.74 95.04 no1 .49 ox .07 25914. TN
21.wu “x.(il
202
KIESH
ANI) TABI,b;
CA: AW
.Y*Z IO,0 BAND WAVENUMBERS
BROII)A IV
(appearing
asextra
lines in the @Z-X’%
0,O Band)
K” 3 5 6
25813.92 25779.89 25828.91 27.64
7 8
25772.17 63 .33
9
10 12 14 16
25849.50 25762.55 25871 .TG 25754.65
8,. I),,
1 .8923 -7.31 x 10-6
1.837 -5.3 x
1 .X1)29 10-G -6.01 x IO-”
I .5303 -4.71 x
I.9598 10-G -6.11 x
IO-6
-51.12
A
The square of t*he wave-fmlction-mixing coefhcientj is given by pe = c/A, where E is the energy level shift, and A is t,he actual separat,ion of t,he pair of int,eract,ing levels (6). The values of t are t,he wave numhrr shift,s of t,he perturbed lines and the values of A are the wave numher differences lwt,\vecn corrcsponding perturbed and ext,ra lines. Figure 2 is a schematic energy level diagram using t,he perturbat,ion with J = 1r’s 1, as an rxamplr. Values of E, A, and p2 are given in Tahle VI for all pcrturhat.ions uhcrc ext,ra lines were olwrvrd. These values are prohuhly more accurate t,han t.hose repart.ed by Wager i/i) l)etcausc of t,he use of low pressure t-o at,tenuate t,he mlperturbed lines and because t,hc A-X 10,3 and 10 ,.’ hands are not significantly overlapped by ot,her hands. Relative t#ransition probabilities ohtained from t,hese newly measured values are in het,tcr agrccmentj than t#hosc of Wager with the rrlativc transition prohahilit,ies measured from relat,ive intensity measurements (IO). LINE
INTENSITIES
A photoelectric tracing of the -4-X lo,:3 hand at a pressure of 1.0 mm Hg is givrn in Fig. 3. The perturhed lines RI ((;!,a), P,(Sli), R,(9>$), and Q2( 151,.;), indicated hy arrows, are free of Mends. Figure -I shows t,hc region of P,(8j2) and Q2( 1.‘; 2) at pressures :< and 0.3 mm. The pert,urhed lines are weaker than
t’BRTI!RBATIONS
IN
EXTRA
(‘N
B.4IYI)S
LINES
-
7
-J
-
15;
IO
15:
0
V
I a
-
1
-I-
-
I I
1QIZ
Q2
I I I I I I I I I I I
P2l
I
P,
RI
-i-
X2X+ RED
15i
SYSTEM
-
-
x 2r+ L VIOLET
SYSTEM
16+
-
‘56
-
149
201
FIG. 3. Photoelectric cnt,e perturbed lines.
KIF:SS ANI) BROII)A
trwing
of the .-l*lI-S*Z 10, 3 Imnd :tt p = 1.0 nun Hg. Arrow
indi-
neighboring lines of the same branch, espcrially at, p = 0.3 mm. Table VII gives the rat.ios of t.he inknsities of the branch envelopes at t,he points of perturhat,ion t,o t,he intensities of t,hc pcrturhed lines for various pressures. This ratio increases wit,h decreasing pressure and is not, t,he same for each pertjurhat.ion. As t,hc presstwe increascn this rat’io appears to approach unit,y. The effect, of pressure on relative intensities in t#hc 13-X 0,O band ia much great,er t,han in the A-X syskm and is discussed in d&ail in Ref. 10. The fact t,hat, at, pressures war 0.1 mm the cxt,ra lines are the strongest lines leads one to spccnlatJe about t’hr rclat.ive rat.es of formatjion of CN in thr ‘4% and B’S elcct.ronic st.atos. The energy lcvols are populat.ed inibally by an ~mknown mrchanism. l’opulat,ion of some levels and depopulation of others rrsults from c~ollisions of CK molecules with t,he various speck prrsrnt. lkpopulation of cxrikd levels also rrsulb from spontanrow emission. At, high presslwr many collisions occur before emission and the line-intensity distribution indicates t#hr smootJh population dist~ril)ut~ion which thr collisions have rst~al~lished ( 9). At low pressure relat,ively frm collisions occur heforr radia.tion and the line int,rnsities are indicative of t,he relative rat)cs of formation of rxrit,ed CN in thr various levels. Comparison of lint intrnsit,ies ill t,hr vkinit~y of the J = I:!,6 prrturhation givrs t.hs brst rst,imatr of thr rclat.ivr rates of formation of Clj in the A% and Bk elertjronic st.ates, insofar as this ronwpt has meaning. J,rt’ IIS IISC at p = 0.10
P=
0.3mm
c 17;
104
P= 3.Omm
3 5d7d
5065
A
206
KIESS
P (mm Hg) 0.3 1.0 3.0 14.0
Q,(3’$) 1.6 1.5 1.5
P,B’i)
AND
RROIDA
&(6’5)
1.5 1 .:< 1.2 1.2
R,(Y’h) 1.1 1.1 1.1 1.1
1.8 1.4 1.1 1 .:3
Qz(lS’i) 2.5 1 .9 1.6 1.1
state. The intensit’y II5 of the perturbed line is probably considerably nffeckd by collixiomal kansfcr between the p&urhing lrvcls (IO), which are about 1.X cm-’ apart, hut] the sum IB + I,, should be lit,tlc aticrt,ed by collisions because the nearest rot,ational lrvcls of t,hc R”?; state arc ahout 60 cm-’ away. The levels nearest the upper stat,es of the two lines on either side of the perkhation are the slightly perturbing levels of the L4”~ st)at,e; t,he nearest of these is about, 10 cm-’ from it#s nearest neighbor in the B” Z state, so that the inknsitics I14 + I16 should not be much affectred by collisions at, p = 0.10 mm. In the preceding we have not considered thr unpert~urbed doublet, components of t,he R”?: st,ate; however, the virtual absence at low pressures of lines from t,hcsc levels indicat#es that collisional transfer to these levels is relat’ively improbable at low pressures. Let us assume that) at p = 0.10 mm c,ollisional t,ransfer is important only I+ t,ween strongly interact’ing levels and that t,he inknsity of a linr whose initial level is a mixed stat,e is proportional t,o the product, of thr pate of formation Fa of CN in the ilk stat,e and the percent’age of ii”11 in t,he mixed state plus the product of t,he rate of formation F, of CN in the H2S state and t,he percent,age of B2Z in the mixed stak. Then I, + I,, and I,, + I16 are unaffected hy collisional kansfer and WC can writp:
116+ IE 41s = IX
FAp;6 + P,(l = FApf., + F,Jl
-
P:,, + F,(l
-
p&j + F.t~:e
+
~46) + FB $5 FBO
-
P%
as the mixing coefficients p14and p16are very small. Estimat,ion of gIs at, pressures near 0.10 mm shows that FA/Fs is greater than 20 (and perhaps as large as lp50). To t#he extent that collisional transfer is important, bet,wcen levels othrr t#han the strongly interacting pairs, this estimat,e is a lower limit, for the rat,io F,/F, of the relative rat,es of formation of CS in t#he A% and B”S electronic states. EstimaGon of FA/‘Fs from the intensity rat,ios $ and g4 at the other point,s of strong interaction yields smaller values, as would be expected since the wavefunction mixing is smaller and the rotational levels are more closely spaced.
208
KIESS
AND
BROIDA
5. A. T. WAGER, Phys. Rev. 61, 107 (1942). 6’. A. T. WAGER, Phys. Rev. 94, 18 (1943). 7. G. H. DIEKE, Phys. Rev. 47, 870 (1935). 8. G. HERZBERG AND J. G. PHILLIPS, Astrophys. J. 106, 163 (1948). 9. N. H. KIESS AND H. P. BROIDA, in “Seventh Bymposium (International) on Com bustion,” p. 207. Butterworth’s Scientific Publications, London, 1959. 10. H. P. BR~IDA AND S. GOLDEN, (‘an. J. Chew. 33, 1666 (1960). 11. Y. TANAKA, A. JURSA, AND F. LEBLANC. in “Threshold of Space,” !M. Zelikofl’, ed.) p 89. Pergamon Press, London, 1957. 12. “American Institute of Physics Handbook.” McGraw-Hill, New York, 1957. 19. “Table of Wavenumbers 2OCQA t.o 7000 A,” U. S. Ijepartment of Conummr, N:t!ionttl Bureau of Standards Monograph 3, Washington, 1). C., 1960. 14. W. G. FASTIE, J. Opt. Sot. dtn. 42, 641 (1952). 15. F. A. JENKINS, Y. K. ROOTS, AND R. S. M~~LLIKEN, Phys. Rev. 39, 16 r.1932).