Vibrational relaxation and electronic mutation of metastable nitrogen molecules generated by nitrogen atom recombination on cobalt and nickel

CHEMICAL PIISSICS LIITCRS

Volume 90. number 6

prrmarlly

1. Introduction

as the result of cfticlent

tton tn the mctastablr Suriacc catalyzed

SKIKIIIOII

observed by hlannell~ et al. charged nrtrogen and oxygen

of mtrogen was first

gen atoms recombmcd stable, electromcally

over cobalt,

by proposmg

1. E\perimentd

present m the discharged oxygen immedlstcly

emuted

Spectra wcrL’ rccordcd Ebert-Fastlc

when a species colltslonally

trans-

bands oi the well-known

first

a Kclthley

giving rrse to a red glow

that extended several mdhmeters wlthout

above IIIC metal [Z].

the presence oi both

the metal and the dlschargcd oxygen.

Atomtc

the red glow [3]. The spectrum

6lO-BR

Hewlett-Packard Nitrogen

wnh J

tube. which

at 1000 V. The shr width

was

pm The slgnal was smphkd

b}

electrometer

and recorded with .I

model 7101-B strtp chart rcsorder

atoms were produced

by !lowmg a ml\-

ture of mtrogen and Inert g35. He or Ar. through

oxygen

was shown not to be necessary for the production

opcratcd

500-1000

0.50 m

m conJunctton

RCA 7101 pltotomultlpher

was typically normally

using a Jarrell-Ash

monochromator

dry-Ice-cooled

3 f$,) state. The N2(B) slate

posmve system oi mtrogcn. No red glow occurred

11131the nuro-

N, molecules \\hose

presence m the gas was marufested muted tt into the N,(B

nurogcn

ntchcl or

on the metal IO form metaexited

hslons WII~ ground-srdtc molcculx

rela\d-

Induced by col-

[I ] when tlley passed dls-

prepared sdver 31 pressures oi =ZI Torr. They mtcrprctcd their observatrons

vlbrdtlorlJ

precursor stxe

of

of the red glow has

never been pubhshrd.

atrcooled

2.45 GHz electrodeless

gen was passed through Gas flowrates

dlschargc

an

I-41.O\y-

a sepdrarc, suntlar dlschargc.

were measured with Porscu~llc flow-

meters, and the total prcssurc was mcasurcd WIIII .I

In the course of a detaded spectrokmetlc

study of

tlhmg hlcLcod

gauge The observations

acre made in

the rzd glow in a flow system, ae have observed that

a IO cm long sectron of I .O cm mncr &Jmctrr

large relattve mtcnslty

skate

changes occur m its spectrum

when much of the molecular inert gas. Using a multtlevel,

nitrogen

IS replaced by

steady-state,

kinetic

model of the processes leading to the emission of the red glow, we have been able to mterprct changes in the red glow spectrum. 0 009-26 11/82/0000-0000/.5

tubmg. Alerage

S-I were typtcal,

boro-

hnear flow speeds oi 8-20

m

and the total pressures uvere usualI)

m the range of 0.5-3.0

Torr.

The metal samples were loops z3.0

mm mncr

the observed

diameter fashioned oi0.15

mm chameter ntckcl or

The changes occur

cobalt wtrc and supported

coax~ally m the flowtubs

02.75 0 1987 North-Holland

457

\Wumc 90. numixr 6

CHIXKXL

PHYSICS LE-ITFRS

of the infers for dts-

by tcl‘lon tubmg JUG downslrzm~

tton III oxygen

that has be2n exposed to a microwave

chxgcd nitrogen .md oxygen The mcral wres were

discharge. We cfimmsre

purch.axl

bawd on IIS low conccnlratton

irom AK3 Vcnrron

Tf12 red glow

Pruducrs

~1 ~fte metal loop was observed by pfxmg

1112mono-

Its opr~zal 3\1s pcrpcndlsular to rhc

chron131or \\IIII

~~1s of ~IIC ilou rubc. Band Jreds of N, iirst positive cmI>sIon Acre m2asurcd ujmg 3 Dlclzgen nictcr and senslilvl[y

corrxtcd

polx

plam-

ustng rhc NO2 contmu-

inn .ind ihc rcjuhs or FontlJn c’l 31 151 The rcixrivc ?ntIsslun micnnry

per second basis) from 3n

fquanrd

individu~f 1 jbr~tion3l level OZ rhc N,(B)

Q~5 zdfsuf_ircd from rhe kit

jttlw. i,

,

posltrvc b.md arcas usmg

1 CT) as a possibdlty

O$b

and the hct that the

rzd ermssion dots not dtfcrease m mtsnsity

when H,O,

which readily quenches O,(b *Et) [IO]. 1sint reduced mto the system. Weinreb and hlannefla [3] convincing atoms as II posslblflty,

wluch 1ssubsranttared

by our ablhty

3 result IO product the

red glow by subjectmg

the incoming

orpgcn

ly elimmated

oxygen

to a weak

Tesla leak-t2srer dtschsry We observe 3 shtii m rcbtw 10 upper vlbr3tion3l

emisston from lower

levels of Nz(B 31’IJ when most

oi th2 nitrogen 93s ~3s replaced by hefturn or argon.

the following rcldtion

Ths rftkt

was interpreted

oicificlent

vibratlonaf

as betng due to chminatton

rslaxation

of N,(W 3Lsu) by

ground-state molecular mtrogcn. We assumed the VIwhcrc I,. v I

1srhc scnsllib~rycorrcctcd band xca, q 1s llw Frmsk-Condon ixror (61 ,md X rh2 wavclcngrh for a psrlxufar

blbrauanal

bratlonal rcldvation procejs proceeded by a au = I! mechanrsm as follows-

b.md. (u’. u”)

3. Rest&s and discussion A similar process 11x btcn sugg2sted by Drryer

The ldcnrny

oi the metastable

on rhc mcraf is uncertain.

iormcd

sumcd II to bc N,(A

3$

Recznt r\pcrm&ts

moicsulcs

Rcetcs et 31. [L?] LIZ.-

in high vlbr3uondf

by Roscnwak

J srrong
couphng

fcvcls.

CI al. [71 mdlcatc

beiwecn

the N,(B

3 HE)

state, which r3iscq the possi-

smtc and Ihs N,(W 3+,) bdny

mrrogcn

in high wbra-

rhat rhs precursor IS N#13L,,)

r8onal levels tn this psper we dttempr I0 crplsin

our

P2rner

and

If I] and Brcnnen ct al. [ 171 for low vtbrational

Irvcfs of the Nz(A )CG) state. Ftg. 1 shows iour red glow emission spectra at various partial pressures of mtrogcn. our results usmp 3 multilevel, steady-

We Interpreted state, kinetx N2(W3fiU,

model which assumes (0 crossover of u) into rhe rmltling

N,(B311,,

mduccd by colIis~ons with O&I

‘L&

u’) sm12

as follows.

e~pcrlmenI3l rewlts by using J. krnerrc model which

~ssurnes N,(W 3&) product

IO be the surface recombination

whtch Ic~ds to rhe prcducrlon

W2 obr.nncd

cxpenmsntal!y

of the red glow.

mdisrmgulshablc

N,(W 3A,, u) + O$

‘&,

u = 0)

u’)+Ol(b1~~,u=O)+LfE2(u).

+ N,(B%,.

(2)

results

usmg cnhcr cobalr or mckel samples at room tsmpera-

(II) Au = 2 vlbraiional

tur2. From olhcr 2\pcrlmrnis

Nz(X ’ Zg) 35shown in 2q. (I), (ei) &J = I \lbrational relaxation of N?(W) by OZ(X 3Z;), and (IV) quench-

surixe

WC have evidence that

rutrides x2 responsible

buMion,

for the cadytrc

og of N?(W 3n,)

We bchev2 [hai O,(a ‘AZ> IS rcsponslblc non3lfy

mducmg crosstng 01 ths N$W

formed by surhcc emrtting N,(B cfnrg2d Jnd O$b

oxyg2n

recombination

3&)

,a,)

for colhmolecules,

of N ztoms, mfo the

stste. Studres o~microwave

&dtcate

that O,(a

I+)

drs-

1s= 10% [8f

t X:) 1s~0.02% 191 2 the gas emergmg region under conc;mons simdw to

from rhe dischxge ours. Furthermore. okygcn

recom-

not the metals thcmseks

states known

these xe Ihe only two metastable to be m nppreclable concentra-

relaxation

of Nl(W 3n,)

by

by the glass wall of the flow tube

and by inert gas. rhe modelhng

To irutiate exponential (6,3)

process we measured the

decrease m the intensity

first positive band as a function

downstream

and total pressures. These measure-

ments ytelded values of the collisional Ehe metastable u=

of distance

of the metal loop at various partial pres-

sures of oxygen

N,(W,

of the strong

precursor,

hfetune,

T~,o~

whilch we took to be

1 I). Values of rp were of the order of

Volume90,

number 6

CHtXltC \L PHI SICS LETTERS

10e3 s. From graphs of rP’ versus oxygen concerwitron we obltined X-,(1I) = 1.3 X lff-13 cm3 mokCUIC-~s-t, &(I I) = 6 0 X IO-t? cm3 molecule-* s-I, 3 rate co&ant of 8.0 X lo-t5 em3 molecule-i s-* for quenchmg of N@‘, u = 1I) by argon, ztrate constant of2.5 X 10mi3 cm3 moleculr-l s-t lor vlbratronal relaxation of N#, u = I 1) by O?(X), and 300 s-* for the desctrvation of N+‘, u = 11) by the wall. These values depend on the assump[ron that 10%of the oxygen passmg through the drscharge was converted to O,(a t$). in our computer model we assumed the rate constants for quenching of N$V, u) by Inert gas and the wall, as well as for vtbratronal relasatron by 02(X), to be independent of u. WCpxametrlzed bolh X-,(o) and k2(v) by equattons of the form,

k,(u) = k;llx,(u)l'J'

(31

and analogously ior k,(u). The cwrgy dcteLts. AEt(v) 2nd AE2(u), rkdcd to cmplo? c’q (3) .md its anzrloguc were cafculated usmg vrbr.numal lcvcls for N,(B) and N,(W) g~vcnby Ccrny L’IJI [ 131. 5238 cm- ’ for the (0.0) bxxi orrgm of lhe O$a '$)-02(b '2;)tr,msiimn [ i-l]. and ’35s cm-t for the roratronless spafmg of tL2 IO\pc’SI two vrbrarlon.rI levels of N,(X) [6] For rhc model c&ulsrtons reported Iwre a2 assumed th.rt ~.~chN,(B. u’) level sIcmmed from a untque precur~r N,(W. u) Ierel. in est.rbhshmg 3 corrcspondcncc bctwwn an N>(B.u’) kvrl and its precursor wc chose UIC mmmrunr energy defect cons~swnt wrh IIIUtcas~ roration.d C~~OIIJ~KMI of the newly formed N,(B) level. The Absolute va1ues

Vc4umc 90. number 6

CtlCAIICAL

PHYSICS LCTTERS 6 0 X IO-” Evldatly, bullon

20 August 1982 to I 5 X IO-l2

cm3 molecule-

s-1.

our model reproduces the mtenwy

dlsirl-

of the red glow well ior 3 v3rrely orc\pcrl-

mrnral sondlrlons. WC arc mirlgucd by the rcsull [hat rahmg enentlallg

equal cncrgy defect r‘\ponrnts

for

kl (u) and k?(u) appcsrs 10 represent 1l1e best cho~cc.

Acknowledgement WC [hank the Umverslly mcnt oi Chemlslry ship support

oi Pennsylvamx

Dcpxr-

ior rrscarch supporr 2nd iello\v-

for one of US (PM).

References

1I] G C

of A ~111: energy dclccfj owd III our model w-c larger than 650 cm-‘.

no

in our cz~lculat~onsv c also

used rhe rddlJtwe I~~~wnss oi N2(B. u’) mcaured WC obl.uned

th? nxc~ni

tbc N,(W. u) mokculej cmwlon

mJtmg vlbr3tlon.d N?(W) IS iormed

relrltw

populJIlonj

by arrapolang

oi I~C Nz(B. u’) IevA

mtcnwes

1131prcssurc ofmtrogrn

oii rapIdly

N$\V.

u = I I ) kwl

rapidly

It appars

IO hlghcr Jnd lower wlues of u. The

IIC’J4362 cm-l

460

results dewed

irom rhe four jpec-

Usmg these paramerers. vnlues oi

range from 5 5 X IO-I3

molecule-’

Fig. T! shows

5-l

I0 7.5 X 10-l-l

.md rhosr Ofk’(U)

range from

cm3

Il.~rw:ch

J Chcm.

H.~r~cch.J. Clwm Chcm

Phks

ii P. BraId&

51 Rrr.

I.51 A. I‘onllJn. C.B. IIc:grr and II 1 SL’IIIII’. J. CIIL’III. PII!, -10 f !964) 6-l. 161 A LOIIIIUS Jnd P.H. Krupcnw. J Phjr. Chum. Rci. D.113 6 (1977) II3 Rokm. I. Nadlcr and S Rossnnahs. Clwm. Ph) 5. LcIIcr> 83 11981) 281. [Sl A hl I-~hct.. B II. h!Jhan and R J. Ubcrs. J Chcm. Ph>s. -11( 1965) 1937. 191 hl A A. Clync. B A. Thrush Jnd R P \VJ)W. Pho~o~hcu~. Ph@rob~ol .l (I 965) 957. 17

I 4

I lOI

below the dljsocIa-

I Thlj iir was accomphshed usmg 121= 0 40

and fl 1 = 0.36 k,(u)

1h31 the rates

oi resuhs calculated usmg our model

apenmcn~al

IrJ m fig.

IO zero par-

In u = I I wrh

non hmlr oi the ground state of nitrogen. 3 compxlson

of

IIIC r&~t~ve

and relatmg lhcm IO the orlg-

levels oi N?(W) mw

hhg

wth

b)

[ 151.

Jcunehomme

Wmn~ll.~. R R. RL~WS .~nd P Ph>s 33 I 1960) 636 [ 11 R.R RCCWJ. C G. bl~nncll_~ and I’. I%>s. 31( 1960) 946 131 >I P.Wcinrcb dnd C G. Xl.mnLIIz. J (1969) 4973 1-l 1 r.c rrhwnicld. K bl CIcnson Jnd F&I Insir. 36 (1963) 29-I.

II I I I I2 I

S J. Arnold, $1. liubo and I: A Obqzlo. Adran Chcm. Ser. 77 (1968) 133. J \i Drqc‘r Jnd D. Pcrncr. J Chcm Phys 58 (1973) 1195 IV.Brcnncn, R.V. Guroajhl and IZ.C Shanc Chcm.

Phbs Lcttcrs 27 (197-t) I38 D Can>. I- Roux. C Eibnirn and J. D’lncan. J. hlol Spwr>. 81 (1980) 127 I I-l I P H. Gruprmc. J. Phls Chum. Rci. Da3 I (1972) -123. [ 151hf. Jcunchommc, J Chum Ph)s 45 (1966) 1803.

I I31