Investigating ion molecule reactions of sodium, potassium, and barium ions with oxygen, nitric oxide, and water in drift tube mass spectromete

Biondi, M. A.

Brown, H. L.

Johnsen, R.

English

NASA Technical Reports Server

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0 , NO. AND H20 MOLECULES 2 
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R. JOHNSEN, H. L. BROWN, AND MANFRED A. BlONPl 
SRCC REPORT NO. 147 
UNIVERSITY OF PITTSBURGH 
PITTSBURGH, PENNSYLVANIA 
https://ntrs.nasa.gov/search.jsp?R=19710007888 2020-03-12T00:21:08+00:00Z
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Reactions of Na', K: and ~ a '  Ions with 02, NO, and H20 Molecules 
( ~ o u r n a l  of  Chemical physics) 
R. Johnsen, H. L. Brown, and Manfred A. Biondi 
Department of  Physics, University of Pit tsburgh 
Pit tsburgh,  Pa. 
January 1971 
Reproduction in whole ox- i n  part is pemissible for any purpose sf the 
United States Goverment. 
4- g a i t - t i i n i  cC lkit X , an', ~a' Ions s i t h  i.:; 1110, arid R,Q M. i e r u j a s  * 
--- a- - --- ,*-,-~- A* -
L 
-".--*- 
R, Johnsen, R. L. Brown @lad M&nfreid A, Bic;ndl 
Department o f  Physics, University of Pi t t sburgh 
Pittsburgh, Pc? , 
Abstrac t  
Ion 1m1ecuI.e reactions of ss8ium, potassium, and b a r i u m  ions  w i t h  
U2, H0, snd H20 have been studied i n  a d r i f t  tube - mass speetro~net~er 
apparatus, The fsP:lawing rate const-ants or  u-pper limits were c~b-bained: 
I 
~a.' + l i pO s. M + ~ a " ~ ~ i ~ 8  + M 
k(?) = 3 . 0  (+ 0 ~ 5 ,  - 0.3)  u 1 .0 '~~  c d / s e n  for M = H ~ O  
6 ir('3) . tde7 (+ 1.2, - 1.) x 0 / f o r  M - He 
K' -r I5p1 "' M 4 K-'-* H;,.O r Ivr 
k ( 3 )  = h.5 + -  2 ,  - 1.5) x lc-" 92n6/sec f o r  M = If-0 
rl 
4 k(3)  = 2.6 ( c . Y ~  - 0 . 5 )  x 10-3° cra /sr; for  M -= HE 
The consequences sf theLe resul t s  Scr the D and E region of the  upper 
&iti~:pF.t?r~ b r i  r43y  described,  
X 
' Ih ic  LcaearrD was s~ppor Led by t h e  Advsnced Research P r 0 j a . 2 ~ ~  Rgcncy nP 
the E~e:;.sf t~-c:l t  CE Defense ~ r 1 3  *trb c ~ ' z n P 4 i  bred by Arny Reeeri r:h IIff'j ce-EerrGc*c 
~nf j i . . r  (!oni,rsr t Eo, 1?P,-3Il l2l,-=(iR0-~-4?10, 
I, - Introduction 
Recently attempts have been made t o  calculate the rnte  of charge 
neutraU.zation i n  the metal ion layer1j2 of the upper mosphere  a t  93 km. 
O f  potent ial  importance t o  such calculations are  the rates  a t  which these 
ions a re  converted from atomic t o  molecular species which ean undergo 
rapid dissociative recombination with electrons, Consequently, we have 
searched fo r  reactions involving oxidation of the metal ions Na', K', 
and ~a' during energetic col l is ions with 02 and NO molecules and have - 
determined clustering reaction ra tes  of Na" and K+ ions with water 
molecules, Inasmuch a s  the binding energies of the metal oxide ions a re  
expected t o  be rather small compared t o  the dissociation energies c f  Q2 
and NO molecules, the oxidation ree,ctions %re expected to  be endothermic, 
requiring substantial  kinet ic  or in te rna l  energy in  the colliding 
partners. A s  w i l l  be shown i n  Section 111, up to  ion kinet ic  energies 
o f -  5 eV the 2-body oxidation reaction ra tes  remin  below our detection 
capabi l i t ies .  
It appears that  the formation of metal ion - water c lus te rs  i s  
not l i ke ly  t o  be an important metal ion loss  process i n  the metal ion 
layer, as  a r e su l t  of the small concentration of water molecules in th i s  
region. Wen i n  the D region, where 8, positive ion of mass 4 1  (tenta- 
t ively ident i f ied as N ~ + * H ~ o )  has been observed with a rocket-borne mass- 
spectrometer? 2 three-bow clustering rekct ion  of the type descri.bed i n  
Section IV mpears too slow t o  account for  the fomaation of this ion ,  
The d r i f t  tube-rnpAss s p e e t r ~ ~ e t e r  apparatus has been described 
i n  an e a r l i e r  paper1' and was used essen t ia l ly  unchanged erL:et for the 
ion source, D.e metal ions were produced by a ho t  filmrgent coated wizh 
the  oxide of the  a l k s l i  (or barium) metal, The f i l m ~ e n t s  were prepared 
according t o  the  description of Blewitt and   ones^ and were found t o  have 
a sa.tisfactory l i fe t ime  i.n the  case of ~a," and K+ sources (- 100 hr ) .  
For BR* qnission the  required temperature was much higher and most 
f i l w e n t s  burned out a f t e r  a few hours. The filaments intended f o r  ~ a "  
ion m i s s i o n  contained enough potassium impurit ies so tha t  the  sodium 
and potassium experiments could be car r ied  out simultaneously with the  
a w e  filament. Pulsing of the  ion saurce ~ T L S  achieved by a p ~ l y i n g  a 
negative pulse t o  a dr@w out electrode located i n  f ront  of the fi lament,  
I n  order t o  i nh ib i t  diff'usion of the  ions t o  the t~aE.1~ sf the  
d r i f t  tube, a l l  experiments were made with helimn as a bu f f e r  gas, The 
water vapor pressure was measured before addit ion of the buffer gas by 
means of a m i l l i t o r  ion gauge which had 'been calibrstefi akhhigher 
pressures against  8, capacitance manometer - MtsLeud gauge s y s t m ,  It was 
found t h a t  t he  water v9,por pressure i n  the arift tube d;creased by up 
t o  5~76 when the  buffer gas (- 1.5 t o r r  o f  h e l i u m )  was adcled, I b i s  e f f e c t  
had a lso  been observed i n  e a r l i e r  measureaent;s w i t h  njtuogen, oxygen and 
carbon dioxide In heliuw a s  buffer gas and i s  a t t r 4 b ~ t e d  to the "sweep- 
out effect",  i . e .  the  in teract ion of the fxc gzces. flowing with different  
velocities t o  the 3on saq2Iling o r i f i ce  and. i r t t c i  t ' l ~ ~  $di.f.'ferentiall-y pumped 
2 > 
w a s  found to be 0 ~ 8 5  cm /V sec i n  H;O v s  21 !Y:,--/v scc In helium) 
causes even FA small water vo,por eoncentr.~tic;n t e :  b5ve a sjgn1fican-t e f f ec t  
l;n 4;,1"1-:- :rtle~.c;ljr& Ci:!tc.s, With 
- ,  presence of heliu.m v:a.s deterrained and used f ~ r  i,he hr~alya;:; $if ' - " a -  L.,~.;: rc:;.:.iicsn 
ra te  rr,easurerr;eni;s. me uncertt?,i.n-ty of ?;his c:in. er,t:.-ii"ii?t~ tit:ter~:iina%ior~ 
i s  estlrnrtted t o  be f 25%" 
The r a t e  constants f o r  c lus ter ing of Nt:" :xnd K:  i l l  Y2C ax therinal 
energies were o b l ~ i n e d  by the "additional residence tf i t :z 'be~hnni  quep 
14 
which has been described in  some dett3,il. i n  Q, preujsub y i c r .  . ln t h i s  
technique the  reaction r a t e  i s  detemined at; thenoai. enemngies by adral"tt,jng 
a p d l ~ e  of' metal ions  t o  the  dr i - f l  region, l u r m n g  the  dy.jt\x f i e l d  off  
f a r  specif ied intervals ,  then turning t h e  f i e l d  bzck  tin ag%in LC- rW&rrg 
the ions t o  the col lector  end o f  the d r i f t  tube nn@ inrr ,  tcc dif'ferenLlal;3vk.lLy 
punlpcd mass sgectrorneter. By rneasvring the reecrc?a,,se 6n :!?e-f;o.i ion  s l g n ~ l  
x i t h  increasing f i e l d  off-time, bath i n  Cke precanee and In t h e  8bsence 
of t;he ret7,ctan-L gas (f120), one can ae?~r .a te  rear d l  ;n :~r?d 6% :f'uzirm effects  
and so obts in  the  desired reaction r a t e ,  
i t a r 1 - t ; ~  for :<-I 7 C2 NO) -* KO" + O(M)  were estirrated to be less than 
io-ii i  cm3/sec 
In the corresponding sodium ion studies, Na0' ions having the 
same rnass a s  K' ions could be distinguished from them only by. t he i r  
different  dependence on the reactant gas concentration and the i r  different  
times of f l i g h t  (Na' has a s l ight ly  higher mobility i n  He than K" so tha t  
reaction products of NaS should exhibit  a character is t ic  a r r iva l  spectrum 
with the onset a t  the time of f l i g h t  of ~ a ' ) ,  The detection sens i t iv i ty  
for  W ~ O '  was therefore somewhat smaller. The upper l i m i t  fo r  the r a t e  
coefficients of Namk + 02(N0) - Na0' + O(N) were estimated t o  be - 10-l3 
crn3/sec. In  addition t o  the absence of product ions, no attenuation of 
the parent ion signal was ever observed. (The upper l imits  on these 
reaction rates  a re  arrived a t  by noting that  a product ion counting r a t e  
equal t o  P. 1% of the parent ion count r a t e  could have been detected.) 
The NO and O2 pressures were varied between 10-3 and 0.5 to r r  
with - 0.2 t o  1.5 t o r r  of helium present. Three bo&y association 
4 
reactions of the f o m  83," + O2 + M 4 Na02 + M could have been observed 
3.f the rate  coefficients were greater than -10-3' cm6/secm N o  indication 
of  such reactions w a s  found. 
I V .  Clustering of Na', K' Ions with H28 
-- 
The existence of a lka l i  ion water c lus te rs  has been known ever 
7 since Munson snd Tyndall discovered the strong ef fec t  of water traces 
on the mobiljty of alkal i  ions i n  rare gases. In our sttxdles vre t r ied 
l ; ~  esi;a'Iilish t h e  mechanism and rate coefficients for the f i j ~ ~ a t - i o n  c;f 
"ie fir::t i*lv.;ter,, i ,e,, the reactlcln Ti%" t28 7 M -* ~ ~ " ~ l - j ~ i l  i M (and 
K' i. K20 i M d ~ ' e K 2 C )  + M). 
The rehetions are thnugkt"rto proceed j n .f.i;rs-srep rol l3  s fon  
processes, involving three particles, In t h e  f i rs t  step a water v~ole:-ule 
at.taches t o  t h e  ion ,  Pe%ving the interrnedliake conplex with .  an excess 
energy. ' k e  ec-znplex rmy e i t he r  break up again with a c"naraeteri.stic 
l i fe t ime  T o r  the  excess energy may be removed i n  a second col9istan 
rendering the  c lu s t e r  s table .  
241e s t ab i l i z a t i on  can be described by a two body r a t e  constant 
% which depends on the  nature of the  t h i r d  body M. I f  the  l ifetime 9" 
i s  large compared t o  the  time (% M)" required for  s tab i l i za t ion ,  
almost a l l  c lu s t e r s  w i l l  be s tab i l i zed ,  and the  reaction w i l l  be lixnited 
by the  rake of formation kl of the  unstable eomp9exes0 An f n c r e ~ s e  of 
the  t h i r d  body concentration w i l l  have no influence on the  rerrctirsn 
("saturated three  body reaction").  I f ,  on the  other hand, T <C (k;, M)-', 
the  r a t e  of c lus te r ing  depends on the  t h i r d  body concentration [MI, md 
the  react ion can be described by a three  body r a t e  constant k(3) - k 7. 
This ease was rea l ized  i n  the  experiment, a s  i s  shown below, 
In  the  experiment, both the  water msleeules and the  helium atoms 
can a c t  a s  s t ab i l i z ing  t h i r d  bocties, although with differen% ef f ic ienc ies .  
I n  t h i s  ease the  measured loss  r a t e  v of K' o r  ~ a *  ions  due Ls c ~ u s t e r i n g  
can be described a s  
where P' r e f e r s  t o  K' o r  ~ a f ,  and kw ( 3 )  and kHe(3) refer t o  the rate 
constants w i t h  M = H20 o r  He,  
After kH, ( 3 )  had been determined by varying the heLiwri density 
at constant water vapor densi ty  ( see  Fig. 3.1, a plat  ( ~ i g .  2 j cf lq,(3) = 
variation with [H~o]. This and the l inear  dependences of. v nn [tie] indicates 
tha-t we are indeed dealing with a t rue (unsaturated) three body reactton, 
The rate eo-nstant.s were o b t a i n e d  a t  T -;: jDO°K nnd tit E/~: = @, 
APthough the  i o n  energy can be w,ri rd eas j  ly 3.m a d s i f  t tu5e, i t becirfies 
very d i f f i c u l t  t o  estab.lish the three bo4y nature b f  the p r x s , i a  4t1e t o  
-the m:c?,ller r a n g e  over whish the densities c a n  be vaLed aJnig3es E J ~ .  
Furthermore, since the unclustered 5 an,; +,nd :he 211i ern~e~kiate a c~n  
complex acquire d i f f e r e n t  energies 5.n the elac"~r.ic f j e l k ; .  , t h  2 r e s u l t x  
could h a r d l y  be expressed i n  terres cf' a s i ~ g l e  pararraeter etyuivalent 
t o  an i o n  t=fiperature for the  reartions, 5%er+rf'oi+e d&tta, ;,r?re t&en 
on ly  i n  the  absence ol' 3, d r i f t  f i r s l B j  whaz-e a1 l ~ ~ r ' t i  :le2 Yei t ' l -  rh.^ S ~ I D ~ ,  
w e l l  def ined tensere twre Tnne f'uuted rxn:erta! ns3 ea l u r  "ih- r;Ce c:, z f f i -  
eient.s, a~proximately 2 ?,$ when M = Hail L and 'i 25% xhan M - H e ,  rer"le;,x 
the  large unrseritalnty ? n %e water vnmcr ri;n:zntret,l on cset er*r.inatlcns, 
A Z I  other souyce:; of error  In the deteminbtil\rrs  re nuch ~~aial ler  and 
hsve therefore noC been d i s c u s s e d  i n  de t a i l ,  
Heavier c l u 3 t e . r ~  af "r;.kre fom Ng,* . ( T T ~ ~ ) ,  d f h  n -- l = 5 53x13 
K* (+ ( ( ~ ~ 0 )  -rrith r. - 1 - Ji were albo observei.  'Ibei r prv:;n-r cnui; . h i V c  
d i s t u r k d  t n e  tyite -o?ct%nt detemmnatl   an,^ ( W F ~ ~ I  t 12 r:tt -3' 
+ke aaike l i  c%rr ) ~n ' y + ? t u l c *  ncbc ui t . i  : 9,1. k, - ; q  f - f  - y i e a ;  
~ ~ t e r  mr;..?.ecu:e .: 715 ? y g  1 enxi :  an: iu,;tere i i 1,' ~~~~r gy7 i - f q i l i l  I e 3 
t o  detach c n s  : r s  term YK.LPC.C LC Prr.:: ;t ~ o t a : i ; ~ ~ i i ,  f r 7 r ~  liY+:e,- t%r ni?s b ~ ? n  
the  ions-rif t  energies so t h a t  a ci,r~-leq,e hresk ~p of st.si,+-.rz >:e>*ivs 
unl ikely ,  
The only o ther  de tem~ina t ion  of ef~i'a'ia,r alkall ion cEjxt,:?rj.ng 
9 react ions  was reported by Fehsenfeld e t  aE , They obtained a value of 
3 x 10-3O cm6/sec f o r  ~a' + H2O + He -. IVafe Hz0 + Be, i n  f a i r  agreement 
with t h e  present  r e s u l t .  
V. Diseussisn 
The absence of detec table  2-body oxidation react ions  fcr the ions 
Na+, K', and ~a' c o l l i d i n g  with O2 and NO rrlcslecufes , even up te ion 
energies of - 5 eV,  suggests t h a t  such precesses are not l i ke ly  to 
contr ibute  t o  eventual charge neu t ra l i za t ion  i n  the metal ion  Payer, 
The r e s u l t s  of  our s tud ies  suggest t ha t  the ?-body c l u s t t r i n g  
reac t ions  of t h e  forrn 
where I' i s  a metal  ion an3 M a third-body nacsl.ecula suck as IV;. sr C2, 
offer rate c o e f f i c i e n t s  i n  the  range 1 9 ~ ~ 9  to 1CFi8 en6,/szce Plus, l n s i  
of E region metal i ons  by c lus te r ing  ought to proceed very sJnf~ ly  
(assuming an H20 densi ty  of 3 x 107 at 93 km., one ribtains a lifetime 
aga ins t  c l u s t e r i n g  of lo7 to 10' ssc). At 82 kin a l t i t ude ,  where a srnrll  
concentrat ion of pos i t ive  ions of mass 41 % a  * H;O) has men a b ~ e r v e ~ i ~  
the  l i f e t i m e  of %a+ ions against d i r e c t  water cluster fox~fist;cn Tz 
reduced to ssec, w3ic.h Is st111 re"u'trer long7,, T f h l ~ s ~  i: -"ee::,c l5ke3y- 
"cat the mas? !;1 'ion er ~ b e r .  i s  rrc.;l, ~ r : " '  R 2 - b ; : r  v tse t f A t -  st' W 2 2  i 
formed i n d i r e c t l y ,  perhaps by the svltchirig r t -2rl lon C O ,  -+ H.-*J 6 - 
I??&' H20 + C02 a f t e r  3-body f ~ ~ : a , t l r : n  of  N&* C02 i n  ?hi iari.inb*c7 1 - 2  
10 the  :nore abundant CO, 
L. 
R, S, Rarc is i ,  SP)F,"EI Reses,rch VITI, QFII,: TPI 113132nd Pvbi:: &ti! ng C; - , 
&nster'd&??_ln, 1968). 
W. Swider, Jr,, Planet, Spec S- i ,  - 17, 123; (2969), 
Rocco S .  Narcisi and Walter Rot;41, Ahv&nc'es i n  Electronisrrs ana 
Electron Physics, V s l .  29, Academic Press ,  I n c a  (1976)~ 
J. Heimerl, R ,  Johnsen, and M~tnSred A,  BisnBi , J, Chen, P'hys, --. 51 ,
50'11 (1969). 
J. P. Blevrett and Ernest J. Jones, Pknys, Rev, 50, 464 (1936)~ 
A. ~ l a n c ,  J, Physique 1, 825 (198)~ 
R, J. Munson and A .  Me DyndaS1, P r r ; ~ ,  Roy, Soc, A --- 172, 28 (?-939), 
S, K. S e ~ r l e s  and P, Kebarle, Can, J, Chm, 47, 2619 (ng69), 
F. C. Fehsenfeld, 22nd G&seous Eleet renics  Conference, 
G. E. Kel ler  &nd R, A. Beyer, 23rd Gasee~xs EXeeLrclnlrra C~nference , ,  
Fig. 1. Effec t  cf  %deli&% as t h i r d  baiy c9n , ~'cII r . e ~ ~ : t l ~ i ~  
frequency at a t o n s t a n t  ritter. v;lp4>r i r n t l  ty ([11:~3] = 
8.4 x 10'~ a o - 3 ) *  n2ts points b t c  t ~ i n  ~ ~ r r e - t u ~ r  f o r  t h e  
"sweep outtt  e f fec t  (see Sec, PI), Mote that  The intercept  
e 
a t  [ ~ e ]  = 0 corresponds to  kw(-7) + 
Fig. 2 Three body coefficient %(j) as function of water vapor 
density, reduced t o  [ ~ e )  - 0 ,  




Reactions of Na/plus/, K/plus/, and Ba/plus/ ions with O2, NO, and H2O molecules

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