Attempt to determine if nitrous oxide is product of nitric oxide photolysis using mass spectrometry and gas chromatograph

Taylor, H. A.

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The major Eisldings of &he projeek relakive to the photo- 
lysis of nitric oxide in  t&e three far-ultraviolet regions 
around 1600 AQ 1470 A and 1236 A were published in the Journal 
article form part of this report. 
of Chemical Physics B, 21078 Mach 3-50 3.965, Reprints 0.E this 
There remains only ~ add t;ol the article a report on *e 
pmblem o f  ni%rsus oxide which .the mciss-spec-metzzic analysis 
indicated present i n  the  phofmlysis products at 1470 A but not 
at 1600 A, not at 1236 A. 
pmduct are conflicting i n  the earlie2 Iitesature, while the 
presence of nitrogen atoms Gogether w i t h  nitrogen dioxide, 
postulated i n  the m e c h a n i s m  of the photolysis, should, accord- 
ing to previous reports in *e literature produce nik?mu$ 
oAde. The problem Fa one of analysis,, The mhecular weight 
of nitrous oxide is  44@ as i s  that of carbon dFoxide. Althoughd 
wi* tp\e use of pure reactants, carbon dioxide could not be 
present among the actual products of phokolysis, neverthelesso 
nitrogen diofide,  a producto can oxidize carbn i n  tho filmeat 
of the ion source of the spectrometero the filaments usually 
being drawn through diamnd diese to y%ePd carbon dioxide, In 
an attempt to recognize nitrous oxide i n  tihe presence of c a r b n  
dioxideo the mass-spectrometric: analysis reported i n  tihe 
reprint, had used the double ionized carbon dioxide value at 
22 as its meaaure, subtracting this amount f r o m  &&e O s t a l  read- 
ing at  44, the dfffersnce taken as nitmus oxide, Since, in 
any caser *e amount of ni t rous oxide is very smabba tbe 
precision of Its measure is  poorB as ene mal1 difference of t he  
tm larger quantitiess carbon dioxide alone and carbon dioxide 
plus nitrous oxide, 
f r o m  nitrogen atoms and nitrogen dioxide by Mis t iakows@,  
depa;.;ds on tihe same analysis and Kistiakowsky's paper reports 
his skepticism concerning the analysis even ai%,er ftmnd2t.ioning 
the mass-spectrometer for a long time," Zn the studico on the 
reaction 05 nitrogen atoras w i t h  ozoneo Taylor and  en reparked 
the presence of nitrous oxide aiid attribuked it to this reac.i%csn, 
L a t e r o  Schiff reports that nitrous oxide is mt prcducxd and 
attributes our findings to carbon dioxide, It VJSS appaxerct %hat 
a new analytical procedure wi3s required, 
been made in various laboratories ammd fihe coun.t-j;.Jp ta 
analyze mix$hres of tihe oxides of nitrogen by gas chmmab- 
graphy. 
There is, howeve@# c0nflic.t: amm2cc t he  clsims, Same: insist on 
ip prel-narlp fra.ctionation, partimlarly GE the ni t~rnyea  ASsxFde, 
R e p o r t s  OR d-us oxide as a 
The experimental evidence for prikrous oxide production 
Several a-Ycmpts have 
Several techniques 05 pmcedtare have k e n  reported, 
- 2 -  
O t h e r s  have clalmed this 'unneeess.ary. 
necessary to dsrelop a eedhnrfque, reproducible perhaps ~rnly Eor 
an individuzrl tmhniciano since none of the mixtures reported 
having been ana:yaed8 containad the minute i311~)unes Wlieved 
be present i n  o w  systems. After care2ully testing suggested 
techniques the following procedure was adopted, 
Obviously it would be 
An Aexmgrapi (-del A-90-~2) gas chromabgraph of the 
Wilkens Instrumen\: Oa, was used With a General Electric 0-3. 
millimlt range ricwarder, The adsorbent was a six inch oolurm 
of silica gel (30-50 mesh) and was used at mom termpaature 
w i t h  helium as t h c  carrier gas at f l o w  rates in the range of 
60-65 ml/min. 
by increasing the ,3ize of sample injected to 20 ml, 
the cell current 4-r 190 m,a, and removing a 220 ohm shunt 
resistor on tihe D, ?. terminal. strip, Samples were injected 
using a gas-sampling valve connected directly Pr, a vacuum 
system,, pressures being measured on aa octoi l  manometer.  
The sensitivity of the instrument was increased 
Increasing 
In elution, N g O  NO and NO:, were renwved in the first ten 
mfnutes and NaO around t w e n t y  minutes. The NO and NO2 peaks 
were not always separakleb the one appearing as a shoulder on 
the other peak at s o m e  3oncentrakiona but the reeenkion of 
the Pa0 perm i t ted  easy separation and therefore recognition, 
By calihratsng standar6 mixtures a€ Na, NO, NOS and N80, a 
lower lidt for the detwtion of Ne0 was establirjhed at I O " % d e ,  
Soras t w e n t y  photo;.pses of No at 1470 A w e r e  made and 
None of these the pmducts analyzed lq the new procedure. 
d ~ ~ w e d  any NaO. 
variation in  the retenticn t ime of Ma0 f r o m  sample 
of the calibrating standards, Ehe photolysis product analysis 
was sandwiched between tww standard runs, Ma NaO peak 
appeared,, 
w i t h  which N a t o m s  might rcact during p k ~ t ~ l y ~ l i . ~ ,  mal% 
amounts of o m e n  were  add83 to the NO before photolysbs, 
were  added injltialxy to the  Em and #e mfxbxre photolyzed at 
1470 A, It is 
apparent that during the perjod of .I=he photolysis 
that might be produced was decomposing, 
earlier work reported in the accompanyhg reprint, was 
actually COS and that under the experimental condi%ions w i t h  
a duration of photn1y:sis of kmr~ 15 to 20 rninuk?s no X3O is 
present among *be final products, 
Since tiiere appeared .to be s o m e  mall 
sample 
In an effort &a increase the concentxaeion of NO2 
S t i f l .  no NaO COulG be found, FfzEi13yo md?, amunts 02 NZO 
The products after :-.he run contained no NaU. 
any 
It is to be. concludeC, tlast the N20, suspected in the 
- 3 -  
. 
Although this recent work is on a system far Scorn a 
parallel to our system i n  mat %e e..rcitation in our system is 
to mudl higher states, t h e 8  xmy' rsnaln some analogy, 33 
investigate this,  as w e 3 1  as to attempt to answer the question 
of the effeck of a change in the duzatdcm of pho4m2ysisa the 
r e s e e  a8slstantr I&, Sethi@ has underkaken as his doetmral 
problem, NO photolysis at 1470Zi by a Elow method, This mrk 
w i l l  pmbably continue during this academic year, After makinga 
as rapidly as possible for the purposes of this repart# the 
transition from iihe former s t a t i c  system to a f l o w  system and 
using the gas-dhrpn latographic analysis method8 he has shown in 
two preliminary runso w i t h  contact times of the o d a r  of 1 m i n ,  
that NaO i s  produced,, He propose8 tx3 fol low this as a function 
of contact tfme w i t h  the pssibili.&y o:Z d%stincyubh%ilg between 
the reaction of NO2 wieh either NO 
carmot affect markedly a e  conclusions of the accrompanying 
paper for the conditions therein skudid .  Su%fice to say, 
however, that lihe l a s t  
still to be said. 
or E atoms, The results 
w, NO phowlysls in the far U-V Lis 
The D i r e r  wishes to express ME deep appreciation to 
'tho N a t i o n a l  Aemnzutfcs and Space A&.ia%sk.ratzLon Eor Hie 
assistance a a t  has made this p r o j e c k  possitiLe, 


Nitric oxide photolysis Final report

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