Reaction of excited oxygen with nitrous oxide 1 yielding nitrogen and oxyge

Greenberg, R. I.

Heicklen, J. P.

English

NASA Technical Reports Server

Scientific Repod No. 343 
REACTION OF 0 ( 'D1  WITH N20 
.- . 
. ,  
I', ., 
. . 
br 
R. I. Greanhrg and 4. P. Hekklsn 
Nwesnk 75,1949 
https://ntrs.nasa.gov/search.jsp?R=19700002595 2020-03-12T04:46:38+00:00Z

Ionospheric Re s e a r c h  
NASA Gran t  NGL-39 -009 -003 
Scientific Repor t  
on 
1 
"Reaction of O( D) with NZO" 
R. I.. Gxeenberg and J. P. Heicklen 
November 15, 1969 
Scientific Repor t  No. 343 
Ionosphere R e s e a r c h  Labora tory  
Submitted b 
P ro j ec t  Superv i sor  
Approved by: 
Labora tory  
The Pennsylvania State Universi ty 
TABLE O F  CONTENTS 
Page 
. . . . . . . . . . . . . . . . . . . . .  ABSTRACT i 
1 
. . . . . . . . . . . . .  REACTION O F  O( D) WITH N 2 0  1 
. . . . . . . . . . . . . . . .  ACKNOWLEDGEMENTS 5 
REFERENCES . . . . . . . . . . . . . . . . . . .  6 
Table  1 . . . . . . . . . . . . . . . . . . . . . . .  7 
A B S T R A C T  
1 The reac t ion  of O( D) ,  produced f r o m  the photolysis  of 
0 
N 2 0  a t  2139 A ,  r e a c t s  with N 2 0  via  
We have u sed  the method of chemica l  d i f ference t o  obtain a n  a c c u r a t e  
m e a s u r e  of k /k = 1 .12  * 0 .02 .  F u r t h e r m o r e  the quantum yie ld  of 2 3 
3 production of O( P),  e i t he r  f r o m  d i r ec t  photolysis  o r  deactivation of 
1 O( D) by N20 ,  i s  l e s s  than 0 .02  and probably  z e r o .  
0 
The photolysis of N 0 with either 1849 or 2 139 A radiation 2 
1 1-5 
leads almost  exclusively to the production of Of D) 
The excited oxygen atom can then r e a c t  fur ther  to produce 0 2 ,  NO, and 
additional N2 
F r o m  the product quantum yields obtained in  previous investigations 
0 
with 1849 A radiation, the rat io  kZ/kg  can  be estimated based on a 
mechanism consisting solely of reactions 1-3. These est imates  a r e  
l is ted in Table I. They va ry  f r o m  0 . 5  to 1 .44 ,  and each est imate has  
- L 
considerzble uncertainty. Fur the rmore  Yamazaki and Cvetanovic 
0 
have a lso  given evidence that at  1849 A,  about 20 percent of the 
p r imary  decomposition might occur via 
This react ion would complicate the analysis.  However i t  should be 
0 
much l e s s  important a t  2139 A,  where there is  barely sufficient 
energy for  i t  to proceed. 
0 
We have examined the photoiysis  of N O a t  2139 A ,  a s s u m e d  2 
reac t ion  4 to  be  neglibible,  and have u sed  the method of chemica l  
d i f fe rence  to  a ccu ra t e ly  compute k /k = 1 .  12 + 0 .  02.  2 3 
The photolyses w e r e  done i n  a quar tz  react ion ce l l  10 c m  
0 
long b y  5 c m  in d i a m e t e r .  The effective radia t ion was  a t  21 39 A 
f r o m  a Phi l ips  93106 E Zn resonance l a m p .  After  i r r ad i a t i on  the 
p roduc t s  (N2 ,  02' NO) w e r e  collected i n  a Toep le r  pump and 
c o m p r e s s e d  before  ana ly s i s .  The compres s ion  induces  the reac t ion  
which goes to complet ion.  The NO is complete ly  consumed and was 
n e v e r  detected,  even though a thorough s e a r c h  was  made  ( P u r e  N 3  
in  the ab seace  of O2 i s  e a s i l y  de tec ted) .  In this  way  the m e a s u r e d  
quantum yield of O2 production,  a 1CI2 1, i s  r ea l ly  @ 1 0 ~ )  -
m 
(1/2) % {NO ). Siace  this  i s  the quantity m o s t  useful  in  de te rmin ing  
k2 /k3  , this method of chemica l  d i f ference reduces  the exper imenta l  
uncer ta inty  by  a f a c to r  of 10 o r  m o r e .  The products  a r e  then 
in t roduced,  through a four  -way s topcocl~ , into a @ow-Mac 40-05D 
chromatograph  uti l izing a t h e r m i s t e r  de tec to r  and a 12 foot long 
0 
5 A molecu la r  s i eve  column.  
Act inometry  w a s  done by photolysis  of IY. 0 in the p r e s e n c e  2 
1 
of a n  exces s  of '.: H to scavenge O( D)  , @ { N ~  ] drops  to 1 . 00 .  In 3 6 
o r d e r  to i n s u r e  that  sufficient  C H was used  i t  was  f i r s t  n e c e s s a r y  3 6 
t o  obtain the r a t e  constant  r a t i o  f o r  the competi t ion between reac t ions  
2 plus 3 with 
Ojl§) + C3R6 -+ products 6 
Experiments were  done with various mixtures of C H and N20.  The 3 6 
resu l t s  a r e  shown in Table 11. As [c3H6]  / [ N ~ o ]  i s  r a i sed  both 
{ N ~  1 and ,{02 } drop; the f o r m e r  toward 1.00, the la t te r  to 
zero.  The r a t e  of react ion 6, R (6 1 i s  equal to R{2} t R{3 } when the 
drop i s  half-way, F r o m  the data  in the Table, k6/(k2 f k3) can be 
estimated to be 8 .0 .  Thus with [C3R6] / [ N ~ o ]  - > 2, a t  l eas t  
94 percent  of the excited oxygen atoms a r e  scavenged by C H and 3 6' 
absolute quantum yields can  be computed, 
0 
The resu l t s  of the photolyses of N 0 alone a t  2139 A a r e  2 
shown in Table 911. The p r e s s u r e  of N 0 was varied tenfold; Ia, by 2 
a factor  of 14. 5; and the extect of decomposition by a factor of 6 .  The 
resu l t s  were  completely icvariant  to any of these variations.  
@ {N } = 1.51 + 0. 11 and {02) = 0.059 + 0,007. Assuming that 2 m 
only Reactions 1, 2, 3 and 5 a r e  impcrtant  k /k can  be computed 2 3 
to be 1.04 + 0 . 4 8  based on  and 1-12 k 0 . 0 2  b a s e d o n  a { o ~ )  m 
It i s  c lear  that the uncertainty in  the vaiue based on {O,} i s  a t  
m 
l eas t  20 t imes smal le r  than that based on { N ~ ] .  This i l lus t ra tes  
the advantage of obtaining differences between two quantities of s imi lar  
value by chemical ra ther  than analytical methods. Our r e su l t  so  
obtained i s  in excellent agreement  with that obtairned by a s imi lar  
0 1 10 
method using NO photolysis a t  2139 A a s  a source of O( Dl. 2 
1 In addit.ion to the reactions of O( D) it i s  necessary  to 
3 
consider the possibility of the presence of the 0( P) which might 
have been produced in one of two ways 
3 If present  O( P) would r eac t  with N O  to ultimately produce O2 via 
No NO would be consumed, but some O2 w ~ u l d  have been produced in 
addition to that formed by Reaction 2. To check this possibility 
some experiments were  done in the presence of 1 t o r r  C H to 3 6 
3 
scavenge any 0 (  P). Under the conditions of the experiments 
1 
the C H removes l e s s  than 18 percent of the 06, D) atoms and usually 
3 6 
3 
much l e s s .  If any O( P) had been present ,  Q,{02} would have been 
diminished. In fact  for  the s ix  runs with 1 tor* of C H Q { N ~  1 =3 6' 
1.48 * 0.15 and Q {o, } = 0,059 * 0.009 which 2 re identical to the values 
m 
found in  the absence of C3H6. It can be concluded that the quantum 
3 yield of O( P) production i s  l e s s  than 0.02 a.r,d probably zero. The 
3 
absence of O( P) means that Reactions 7 and 8 a r e  unimportant, 
and a lso  requi res  that Reaction 4 be negligible, a s  it would be 
followed by  
The au thors  thank Dr .  R. Simonai t is  f o r  his st imulating 
help.  This  w o r k  was  supported under  NASA G r a n t  NGL 39-009-003 
and N. S .  F, Gran t  GP-5611 f o r  which we are grateful ,  
'(~5611 062 '6L .j,S -XI 6salio~ *v OM pue uo:llaTse3 "j~ -3 
- '(9961) 8882 '5~ '.sliyd .may3 ef ',?~noue?an3 .f pue uo7saJd .A 
- -(£96~) 2061 "g '*sLyd *way3 -1 '3!nouejan3 '8 pue :yez-emeA 'H 
/ 
T A B L E  I 
Va lues  of k2 /k3  
VALUE BASES 
---- 
R E F E R E N C E  
a lo2) 7 0 . 5  MacDona ld  6 
m (N2)  = 1 . 4  N o y e s  7 
1 . 5 6  ( 1 . 1  - 2 . 2 )  @ { N 2 j :  1 . 6 1  * 0 . 0 8  Zeliicoff a n d  A s c h e n b r a n d  8 
1 . 3 8  ( 1 . 2 2  - 1 . 5 6 )  @ {o,] - 0 . 5 8  -t 0 . 0 3  Zei ikoff  ahid A s c h e n b r a n d  8 
0 . 7 8  ( 0 . 6 4  - 0 . 9 6 )  {N, ]=  1 . 4 4  + 0 , 0 5  C a s t e l l i o n  a n d  N o y e s  9 
1 . 4 4  (NO)  2 0 , 8 2  C a s  t e l l i on  a n d  Noyes  9 
1 . 0 4  ( 0 . 6 7  - 1 . 6 3 )  (N2)  = 1 . 5 1  + 0 . 1 1  T h i s  w o r k  
1 . 1 2  * 0 - 0 2  @ ( 0 , )  = 0 . 0 5 3  i 0 .007  T h i s  w o r k  
m 
TABLE I1 
0 
Photolysis of 300 T o r r  N 2 0  a t  2139 A and Room Tempera ture  
in the P re sence  of C3H6 
[c3H6I,  t O r r  Ia' p / h r .  Exposure  t ime, h r s .  m {02)(") {N, ) 
( a )  mmlo2) = a lo2} - (112) a {NO) 
(b)  average value taken f r o m  Table 111, C 
TABLE IEI 
Exposu re  
t ime ,  
h r s .  
(A) 3 0 t o r r N  0 
2 
(B) 100 t o r r  N 2 0  
( C )  300 t o r r  N 2 0  
0 
Fhotolys is  of Ni t rous  Oxide at 2139 A 
and Room Tempera tu r e  
(a,) @m{021 = @ {02 - (112) ~ ( ~ 0 1  
(b) 1 . 0  * 0 . 2  t o r r  C H p re sen t  3 6 


Reaction of O/1D/ with N2O

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