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Ionospheric Res ear ch

NASA Grant NGL-

Scientific Report

3 "Competitive Reacti0.n of O( P) with Ozone and Carbonyl Sulfide"

D. C . Krezenski

February 15, 1971

Scientific Report No. 368

Ionosphere Res ear ch Laboratory

J, S.. Nisbet, Professor of Electrical Engineering Pr oj e c t Supervisor

\

Approved by:

A. H. .Waynick, Director Ionosphere Research Laboratory

The Pennsylvania State University

University Park, Pennsylvania 16802

TABLEOFCONTENTS

ABSTRACT. . . . . . . . . . . . . . . . . . . . I. INTRODUCTION . . . . . . . . . . . . . . .

Previous Investigation of the Rate of Reaction of O(3P) Atoms with O3 . . . . . . . . . . . . . . Present Investigation of the Rate of Reaction of

3 O( P) Atoms with O3 . . . . . . . . . . . . . Pho to1 ys i s of Ozone . . . . . . . . . . . . . Previous Investigation of the Rate of Reaction of

3 O( P) Atoms with OCS . . . . . . . . . . . . Present Investigation of the Rate of Reaction of

3 O( P) Atoms with OCS . . . . . . . . . . . .

Page

ii

1

1

2

4

5

6

Previous Investigation of the Rate of Reaction of 7 3 8( P) Atoms with 2-'I'rifluoromethylpropene . . . .

Photolysis of Nitrous Oxide . . . . . . . . . . 7

. . . . . . . . . . . . . . 8 11. EXPERIMENTAL. 3

The Competitive Reaction of O( P) with Ozone 8 and Carbonyl Sulfide . . . . . . . . . . . . . 8 The Vacuum Line . . . . . . . . . . . 8 Optical System . . . . . . . . . . . .

Gas Chromatograph . . . . . . . . . . 8

Reagents . . . . . . . . . . . . . . . 10

Temperature Control . . . . . . . . . . 11

Procedure . . . . . . . . . . . . . . 11

3 The Competitive Reaction of O( P with 2-Trifluoromethylpropene and Carbonyl Sulfide . . . 12

The Vacuum Line . . . . . . . . . . . . 12

Optical System . . . . . . . . . . . . 12

Gas Chromatograph . . , . . . . . 12

Reagents . . . . . . . . . . . . . 14

Temperature Control . . . . . . . . . 14

Procedure e . . . . . . . . . . . . . 14

I11 9 RESULTS. . . . * . . . . . e . . . . 15

Reaction of O( P) Atoms with O3 and QCS . . . . . 15 3

n

Reaction of OI’P) Atoms with TMP and OCS a e . 28

IV. DISCUSSION e . . . . . . . . 34

Reaction of O( P) Atoms with O3 and QCS . . . . . 34

Reaction of O( P) Atoms with TMP and OCS . . . e 46

Determination of the Absolute Value of kl . a . . . 49

V. SUMMARY . e - . . . . . . . . . . 53

3

3

BIBLIOGRAPHY . . . a . . e . . . . . . . . . . 54

ABS TRACT

3 The competitive reaction of O( P) atoms with 0 and OCS

was investigated in the temperature Tange 197OK - 299OK. The

relative ra te constants for the reactions

3

ill 3 O( P) t o3 - 202

o ( ~ P ) t ocs - co t SO (3 )

were determined and found to be independent of irradiation time,

absorbed intensity, and the addition of a foreign gas.

-11 3 value of kl = 1.1 x 10

calculated from a pre-determined value of k

3

The absolute

exp(-43JO/RT) c m /particle-sec, was

3 '

The value of k was determined f rQm a similar competitive

3 study of O( P) atoms with 2-trifluoromethylpropene (TMP) and OCS

in the temperature range 300°K - 523OK. The value of k3 = 1.63 x

3 exp(-4500/RT) c m /particle-sec, was calculated from the

3 known ra t e constant of the O( P) reaction with TMP.

The value of kl determined is in excellent agreement with

the value k l determined from the collective previous works in the

temperature range 300°K - 1150OK.

i

CHAPTER I

INTRODUCTION

The photochemistry of atmospheric ozone is one of the more

important problems of the stratosphere.

vertical distribution of the atmospheric ozone shows large variations

with latitude and season and with weather conditions. The maximum

It is well known that the

of the ozone density is, on the average, located near the altitude of

- 10 19.8 km. and the average value of the ozone density i s 3 x 10

3 -4 gm/cm corresponding to a partial p ressure of about 1.2 x 10 2 of Hg.

mrn

The existence of ozone in the atmosphere is due to the photo-

dissociation of 0

react with oxygen molecules to form ozone.

0 disappearance is via 0 atom attack. Therefore,' investigations of

the ra te laws of these reactions a r e important in the understanding

of the photochemistry of atmospheric ozone.

molecules into oxygen atoms which subsequently 2

The major route of

3

3 Previous Investigation of the Rate of Reaction of O( P) Atoms with 0,

The reaction

3 has been investigated by several groups.

determined the ra te of this reaction directly a t high temperatures

(around 850°K) through the use of shock tube experiments.

and Schumacher4 studied the decomposition of ozone a t 373OK.

reaction was further studied by Castellano and Schumacher5 who

Jones and Davidson

Glissman

The

- 2 -

photolyzed ozone with r ed light around room temperature. Mathias

and Schiff studied the recombination of oxygen atoms in a s t ream of 6

discharged oxygen containing a small percentage of atoms, by

measuring simultaneously the ozone and oxygen concer?trations using

a mass spectrometer.

investigations is shown a s an Arrhenius plot in Figure 1.

A summary of the data obtained f rom these

The data fall mainly into three groups: Jones and Davidson's

a t about 850°K, Glissman and Schumacher9s at about 373OK and

Castellano and SchumacherZ s around 300°K. Collectively the three

groups of points cover a wide range of temperature and fall on a

straight line. The recommended value of the ra te constant based 7

3 on the collective data is k l = 2 .00 x los1' exp(-4790/RT) cm /

particle-sec. Although there i s too much scatter to determine an

Arrhenius expression from either the Jones and Davidson o r the

Glis sman and Schumacher data, the Cas tellano and Schumacher data

indicate an activation energy considerably lower than the collective

data.

3 Present Investigation of the Rate of Reaction of Of P) Atoms with 0,

In view of the discrepancies found in the l i terature values for

the activation energy of reaction B, i t seemed appropriate to study

this reaction in a different system.

of ozone and carbonyl sulfide were irradiated with wavelengths

exceeding 4300 A.

of 0

ra te constants were obtained.

In the present study, mixtures

3 The O( P) atoms produced f rom the photolysis

reacted with either the carbonyl sulfide o r ozone; thus relative

The present study was conducted from

3

- 3 -

- 11.5 1. JONES 81 OAVIOSON ( 3 ) o G L I S S M A N 8 SCHUMACHER (4) w

0 0 C A S T E L L A N O 8 SCHUMACHER ( 5 ) a, fn I Q)

0

U M A T H I A S S S C H I F F (6) -12.0

.- c L -12.5 a

E -13.0

0

\ rr)

0

2s U

Y - g -13.5 -

-14.0

I 2 3 4 IOOO/T, OK-'

FIGURE 1

OBSERVED VALUES OF kl

- 4 -

room temperature down to 197OK, while the previous stiadies were

car r ied out f rom room temperature up to 850 K. 0 Thus, the

reciprocal temperature range was expanded by nearly a factor of

two.

Photolysis of Ozone

When ozone is photolyzed in the laboratory or in the atmo-

sphere, it dissociates into an oxygen atom and oxygen molecule. The

electronic s ta te of the atom and molecule depend on the wavelength

of the photolyzing radiation.

26 kcal/mole.

The bond dissociation energy is

8 Energy in excess of this can cause electronic

excitation of the oxygen atom or molecule. The electronic energies

of the first few excited s ta tes of oxygen atoms and molecules are

given in Table 1.

TABLE 1”

ENERGIES OF THE FIRST F E W ELECTRONIC STATES OF OXYGEN ATOMS AND MOLECULES

Atomic of Molecular State

Energy Relative to Ground State

(kc a1 / mole)

0 . 0

45.4

96.6

0 .0

22.5

37.5

a. See references 9, 10 and 1 1 ,

- 5 -

In the present study the principa3 lines transmitted through

the f i l ter used were 4358 A, 15% trans’mission, 64.2 kcal/mole,

and 5461 A, 82% transmission, 51.4 kcal/mole. It can be seen f rom

Table 2 that at these wavelengths, the ground state oxygen atom,

O( P) is produced. 3 Although it is energetically possible to produce

1 1 the excited 02( A ) and 02( E - ) electronic states, there is no g

1 1 g

1L evidence for their formation. The proposed mechanism for the

photolysis of ozone at these wavelengths is:

(1) 3 o3 t O( P) - 202

TABLE 2‘

WAVELENGTHS (A) BELOW WHICH IT IS ENERGETICALLY POSSIBLE TO PRODUCE THE INDICATED SPECIES

FROM O3 PHOTOLYSIS

o ( ~ P) a 11,,400 5900b 4600b 2300 1700

O( D) 4, loob 3 100 2600 1670b 1500b

O( IS) 2, 340b 1960 1790 1290b 1080b

a. Ground State c. See reference 12 b. Forbidden Transition

3 Previous Investigation of the Rate of Reaction of O( P) Atoms with ocs

The reaction

o ( ~ P ) ocs - co SO (3 1

- 6 -

has been investigated by Westenberg and de Haas13 who determined

the rate directly over a wide range of temperatures (273O - 808OK),

employing a fast flow reactor with ESR detection. The ra te constant

k was also determined by Hoyermann, Wagner and Wolfrum over

the range 290° - 465OK.

reactor system with ESR detection. Homann, Krome and Wagner

determined the ra te constant k in the temperature range 300° - 1150°K while investigating the oxidation of CS2 in an isothermal

flow system under reduced pressure and high dilution with iner t gas.

The observed values of k a r e summarized in Table 3,

14

The method used w a s also a fast flow

3

15

3

3

TABLE 3

OBSERVED VALUES OF kg

Inve s tig a tor s 3 k3 (cm /mole -s ec)

13 1 . 9 x 1013 exp(-4530/RT) Westenberg and de Haas

13 14

14 15

12

6.5 x 10 exp(-5500/RT) Homann, Krome, and Wagner

1.2 x 10 exp(-5800/RT) Hoyermann, Wagner, and Wolfrum

9.8 x 10 exp(-4500/RT) This work

<action O( 3 P) Atoms with OCS

The present investigation was conducted to t ry to resolve the

discrepancies in the values found previously for the activation energy

of reaction 3 and also to check the self consistency of the r a t e data

obtained for the reaction of O( P) atoms with 1-butene,

2-trifluoromethylpropene (TMP), and carbonyl sulfide. In this

3

- 7 -

3 investigation the O( P) atoms were produced by the mercury

photosensitized decomposition of nitrous oxide with 2537 A radiation

in the presence of mixtures of TMP and OCS.

3 Previous Investigation of the Rate of Reaction of Of P) Atoms with 2 -Trifluoromethylpropene

The reaction

o ( ~ P ) t TMP - A t E (4)

where A represents 2-trifluoromethylproplyene oxide and E represents

2-trifluoromethylprbpionaldehyde, yas studied' by Moss, and

Jennings, l6 who found the reaction to give almost exclusively

(> 9570) the addition products A and E.

temperature was found to be 0.077 relative to that of 1-butenewhose

ra te constant is well known.

value obtained by Simonaitis and Heicklen, l7 who extended the temper-

ature range from 298

The ra te constant, a t room

This value is in good agreement with the

0 - 548OK. They found the Arrhenius expression

3 for the ra te constant to be equal to 9.1 x lo1' exp(-2220/RT) cm /

mole - s ec .

Photolysis of Nitrous Oxide

3 O( P) atoms can be produced by the photolysis of nitrous

oxide in the presence of mercury with 2537 A radiation. l8 The

mechanism is:

3 Hg t hv -C Hg ( P1)

3 H ( PI) t NZO - N2 t O(3P) t Hg g

CHAPTER I1

EXPERIMENTAL

3 The Competitive Reaction of O( P) with Ozone and Carbonyl Sulfide

The Vacuum Line

The high vacuum line was constructed of Pyrex glass and was

free of mercury and grease; teflon stopcocks (West Glass) were

used throughout. Figure 2 i l lustrates the location of the reaction

cell and other components. The pumping system consists of a

three -s tage oil diffusion pump (Consolidated Vacuum Corporation)

and a Welch Duo-Seal oil pump (model 1399). Ozone pressures

were measured on a sulfuric acid manometer, and carbonyl sulfide

pressures were measured on an alphatrsn gauge (NCR, type 530).

Optical System

A cylindrical quartz cell, 10 cm. in length and 5 cm. in

diameter, was used as a reaction vessel. A Hanovia medium

pressure mercury lamp (model 30620) was used as a source of

radiation. A Corning (CS 3-72) fi l ter was used to remove radiation

below 4300 A.

Gas Chromatograph

Gas chromatography was used for the quantitative analysis of

CO and C02.

(Gow Mac model 10-=1;77), a power supply (Gow Mac model 40-OlZ),

The gas chromatograph system consisted of a detector

and a recorder (Texas Instrument, Servo Riter 11). The detector

was kept at O°C and a current of 15 milliamperes was provided by the

power supply.

- 9 -

a a 3 w 0

J a

I L

Y 0 0 0 a 0 b v)

I @

- 10 .-

Helium, pas sed through indicating dr ier i te and ascarite, was

used as the c a r r i e r gas.

A porapak (type Q) column, twelve feet long was used to

analyze for C02, with a c a r r i e r gas pressure of twenty-five psi.

The CO was analyzed on a molecular seive (5A) column three and

one-half feet long with a ca r r i e r gas pressure of fifteen psi.

Reagents

Ozone was prepared by passing an electrical discharge f rom

a tesla coil through the glass walls of the vacuum line containing

oxygen (Air Products, research grade). The ozone was condensed

in a liquid nitrogen t rap and degassed. The discharge process was

relatively fast (5-10 minutes) i f the oxygen pressure in the line was

five to six tor r o r less .

argon (-186 C) to liquid nitrogen (-196OC) with continuous pumping.

The ozone was distilled twice f r o m liquid 0

Carbonyl sulfide was purified by passing it through a one inch

diameter glass tube contaihing about three inches of drieri te and about

ten inches of ascar i te (8-20 mesh) and then distilling i t twice a t

- 13OoC (n-pentane slush).

The carbon monoxide (chemically pure) and the carbon

dioxide (bone dry) used to calibrate the gas chromatograph were

from Matheson.

The tetrafluoromethane (Matheson) used to study foreign

body effects was purified by passing i t through ascar i te and distilling

it at -160°C (iso-pentane slush).

The helium used to study foreign body effects was the same

as that used as the ca r r i e r gas in the chromatograph,

- 11 -

Temperature Control

The temperatures were maintained by submerging the cell

in an unsilvered dewar filled viith a liquid at the desired temperature.

The length of the runs were short enough so that the temperature did

not vary by more than 1.0 degree.

the temperature at 273°K, with ca re being taken to keep pieces of

ice out of the path of the radiation.

maintain that temperature.

with a mixture of dry ice and acetone.

Ice water was used to maintain

Water a t 299OK was used to

The 197OK temperature was maintained

Acetone cooled with liquid

nitrogen was used to maintain the 228'K temperature.

Procedure

The vacuum line was pumped down to l e s s than one micron

on the alphatron gauge.

reaction cell, the carbonyl sulfide was admitted into the cell simul-

taneously with the opening of the shutter of the lamp. The lamp was

previously allowed a t l eas t 20 minutes to warm up. At the end of the

After degassing the ozone and filling the

irradiation period the contents of the cell were allowed to expand

into a liquid nitrogen trap, where the ozone, carbon dioxide, and

carbonyl sulfide condensed.

expand filling a collecting tube.

allowed for equilibrium of the carbon monoxide after the expansion.

The aliquot of carbon monoxide was then removed for analysis.

remaining condensed gases were distilled at -186OC to remove the

excess ozone. The carbon dioxide and carbonyl sulfide were then

condensed into a liquid nitrogen t rap and removed for analysis.

The carbon monoxide was allowed to

Fifteen to twenty minutes were

The

- 12 - 3 The Competitive Reaction of O( P) with 2-Trifluoromethylpropene

and Carbonvl Sulfide

The Vacuum Line

The high vacuum line was constructed of Pyrex glass in the

usual fashion. Figure 3 i l lustrates the location of the various

components.

pump (model 1402) comprised the pumping system.

A mercury diffusion pump and a Welch Duo-Seal oil

P re s su res less

than 10 to r r were measured on a McLeod gauge (Consolidated Vacuum

Corporation), p ressures greater than 10 tor r were measured on a

mercury manometer. A thermocouple gauge was used to monitor

the admission of gases to the line.

Optical System

The same cell described ear l ier was used as a reaction

vessel.

was used as a source of radiation.

A Hanovia spiral low pressure mercury resonance lamp

Corning (9-30) f i l ters were used

to remove radiation below 2200 A .

Gas Chr ormatograph

The gas chromatograph system used was the same as that

described ear l ier .

A molecular seive (5A) column, seven feet long was used to

analyze for nitrogen and carbon monoxide.

was twenty psi.

The ca r r i e r gas pressure

A ten foot Kel-F oil number three on Chromosorb P

column was used to analyze for 2-trifluoromethylpropionaldehyde~

and 2-trif luorom~thylp~opy~ene oxide.

38 C and a c a r r i e r gas pressure of thirty ps i was used.

The column was kept a t

0

- 13 -

W J a.

0 = gs W I t-

I

Y 0

' 0 0 a 0 t- v)

f QD

- 14 -

Reagents

Trifluoromethylpropene-2 (Peninsular Chem Research, Inc.

w a s purified by passing it through ascarite and degassing it at -196OC.

The carbonyl sulfide was purified in the same manner as

described earlier.

The nitrous oxide (Matheson) was degassed at -196OC.

Temperature Control

The cell was placed inside an aluminum block furnace, where

the temperature was maintained by a regulator (Dohrmann, Model

13001, which controlled it to * O o 5OC.

Procedure

The vacuum line was pumped down to l e s s than one micron.

Trifluor omethylpropene-2, carbonyl sulfide, and nitrous oxide were

admitted into the reaction cell and irradiated.

to w a r m up for a t l eas t ten minutes pr ior to irradiation.

of the irradiation period the cell was opened and the contents were

allowed to expand into the line through a liquid nitrogen t rap which

condensed the aldehyde,, epoxide, nitrous oxide, and carbonyl sulfide.

The non-condensibles, nitrogen, oxygen, and carbon monoxide were

collected by a Toepler pump into a tube for analysis,

oxide and carbonyl sulfide were distilled away at - 13OoC (n-pentane

slush) and the remaining aldehyde and epoxide were condensed into

a collecting tube for analysis..

The lamp was allowed

At the end

The nitrous

CHAPTER I11

RESULTS

3 Reaction of O( P) Atoms with 0, and OCS

The resul ts of the photolysis of mixtures of ozone and carbonyl

sulfide, in the temperature range 197°-2990K, are shown in Tables

4-10. Ozone pressures of approximately 3 tor r and 12 to r r were

mixed with OCS pressures varying between 0 . 5 t o r r and 223 tor r .

The products CO and C 0 2 were identified and quantitatively analyzed.

The following expression for the theoretical ra te of produc-

tion of COY R(CO)t, can be derived from reactions 1-3:

where I

ozone to produce COz, R(CO), must be corrected for the CO lost

through this reaction. Since one molecule of C 0 2 is produced for

each molecule of CO lost, R(CO), can be written as R(C0) + R{C02),

where R ( C 0 ) and K(C02) represent the measured rates of production

of 60 and C02 respectively.

is the absorbed intensity. Since CO is known to reac t with a

t The previous expression for R ( C 0 )

becomes :

r 1

At constant ozone pressure, the R(C0) + R(C02) increased

with increasing OCS pressures and then leveled off, approaching a

- 16 -

@I

+ 00 00 m 0

m o o o m m a 0 0

d Ln [c-

0

d m N

0

F 9 0

0

d 0 ['

0

9

0

m d 0

0

w d

rr)

d 0

d

00 p.

N

0 u @I w

U

m m 0

F 9 N r r , 0

0 0 0 0

e d

I+

F d c r d d

Cr) 9

N

d

m m d 0 0

00

0

0

d

d n

0 u U

00 N 0

0

N [ ' N d 0 0

0 0

m N 0

0

\

n a 0 u u

8 ;- do 2 .rl c,

rd 0 k a

do

2J r r l u u

k

$3 0

u Id a, k

.* c, [ ' m

m m m m

* m m

w 0

k 0 w 2

* N

N w o N 9

.A d

0 c,

i v) a, k pl a, k

a, rd k

-44 9

d N

* a, u a, k k 0 u

c, I I h

0" u 4-,

N

N N

S c r 0 F

N

m 0

rr)

- 17 -

Ln

w 4

E 9

W

4 5

t4 3.1 z 0

d 4 u

n G: Cn

a

8

Ki

w u z w d Pi w x E-r z w z 0 N 0 6( 0

H

2 u1 3.1 t4 0 E 0 E P4

4 n

ON

0"

u u \

n a

u u

4 n

0 u w \

h a

0 u u

n d

H 2 I

id *i Y

m co 0

0

I? 9 m 0

* m Ln

0

Ln

0

4 4

0

co 0 4

4 0

4

cz\ 9 4 4

m m

0

4

m 0

m 4

4

Ln * Ln 0

Ln 0

0

0

4 4

m 4

In P

* 4 4

N 9 4

0

co 9 m 0

m * 4

N Ln 0

* * 0

0

4

4 4

N 0

N

co 0

N 4

9

N

0

4

0

0

* N

0

4

b N 0

0

4

4 4

-P

-4

0

N 4

9 4 m 0

m 4

0

l- * m

Ln I?

0

cz\

0

0

4

* 4 4

m 9

m N 4

Ln 4 In

0

I?

0

9 4

Ln

cz\ Ln 0

cz\ cz\ 0

0

m 4 4

m co N

N

N 4

.r( c,

: a, k 24 k rd a u) c, d a, u) a, k PI a, k a

tii; 2 .+-I c,

a 0 k a 0 u rw 0 a, d k I I

c,

+ 0 u d qr

d 0 .r( c, s

0"

a 0 k P,

V W 0 a, d k 11

c,

.PI c, : -2 a, k

id a k 0

a a,

w

U

co 9 N

0

0

0

9 4 t-

o

0

4

4 -@ 0

0

9 00

N

Ln 6-l

9 co N

-@ I' m 0

4

0

m 0

4

-@

0

4 m 0

0

r\l 0

cr)

N 0

N

N 0

m

-

9

0

r-l

0

Ln 4

m a 0

N N 0

0

I' 9

N

4 co m

t- 9

N

18 -

9 N 00

0

m N

0

m

P I'

0

co 9 0

0

a3 0

m

N co N nl

co 0

m

E!

!

2

kl

.rl c, U

k 4:

a rn c,

rn a, k a a, k a

d 0

u rd a, k

.I4 c,

5 .rl

4

m c,

$ rn a, k a a, k 4

5 s

.I4 c,

a 0 k P,

0 u w 0 a, rd k I I

c,

A

0 0 d -

- 19 -

* m M

0

dc M N

0

rr) 0

r-l

d 9 M

0

0

0

N eJ

M

l-4 0

r-l

m rn N r

Tc

* 0

l-4

F 9 0

0

m 9

l-4

9 co 0

e M 0

0

co 0

4

N 0

N

M 0

rr)

00 F In 0

0 4 . 0

M l-4

N

N co 0

Ln l-4 0

0

Ln co M

rr) 9

rr)

9 co N

Ln N r- 0

0 Ln

0

9 M

N

9 Ln

0

co F 0

0

9 m m

9 In

r-

* m N

Ln Ln 00

0

0 Tc

0

F

N

F Ln

0

F d

0

4

9 m M

9 * M N

* m N

.PI c, U cd a, k 24

a 1

! m c,

m a, k a a, k a

- 20 -

co 00 0

0

0

0 .

M 4

4

0

4

m N 0

0

Ln co N 4

4 0

4

m t-

0 4

t- Ln 4

0

M

0

M * 4

m 9

0

9 0

0

m N 4

Ln I-4

co 0 4

w P- I-4

0

cr, 4

0

b 4

N

9 Ln

0

M 0

0

Ln

M 4

N 0

N

rr) m 0 4

N rrt M

0

M

4

t-

cr,

m N

0

Ln rc) 0

0

Ln Ln

4 4

N

M

N

N I-4

M 9 M

0

w 0

9 co 4

0 9

0

t- N 0

0 .

Ln w 4 4

m 4

4

N d

9 9 9

0

N

0

In N

m

M m 0

I-4 Ln 0

0

N

4 4

In

N N

m P-l

4

9 N co 0

4

4

m 0 4

N co 0

0 N

0

Ln Ln

4 4

0

4 co

N

nl 4

F: 0 .rl 0

ki a, k A k crf a m 0

5 m a, k a a, k a

- 21 -

Ln 9 N

0

M crl 0

0

In m e 0

F-4 CT

0

0

0

Ln 9

rr)

4 0

4

* co N

I+

CF N

0

0

0

m 0

4

0

I+

d 9 0

0

VI

N

4

9 P-

N

03 m 0

0 rr)

0

4

4

9 * 0

m 0

0

co 9

rn

9 dl 4

[r 00

N

9 * 0

P- 9 0

0

P- 9

4

CT 00

0

* P- O

0

co P-

Fr)

0

rr)

Ln CT

N

N [r

0

* rc) L n

0

rr) N

N

9 rr)

0

Ln CT 0

0

Ln co cc)

c-0 CT

9

0

Cr)

CF co 0

0 63

d

9

N

4

F-4 P- In

0

9 4 0

0

co P-

m

Ln CF

m n3

Ln CF

N

co CT

0

0 m 4

m N

9

P-

0

d

9 0 Ln

0

P- 9

rr)

dl 0

0 p.

9 co N

F: 0

u (d a, k 2.4

Td

.rl c,

2

g m c,

m a, k a a, k a

- 22 -

0 4

w I4

c E-1

a

w Q b.4 4 5

I4

0

p: 4 u h 0 w

w w p: PI

E-1 z

+I

v)

!2 a

m

k!

E H

0 N 0 G-l 0 v) H

2 I4 0 E-1 0 x PI

d n 0 u U \

n a

0 u U

h

.!i & E i Y

h

n k

- -

9 m 0

0

0

0

rr) N

4

0

4

4 Ln 0

0

M)

N 4

4 0

4

m rr)

4 d

N m 4

0

rr) rr) N

0

cr)

N

00 co I'

0

co cc) 4

0

N

m 4

N 0

N

9 F 4 4

co 9 N

0

rr) rr) 4

0

Ln

rr)

I' co 0

00 4 4

0

9

rr) d

rr)

rr)

4

N 4

rrr 9 rr)

0

rr) rr)

0

I' d d

Ln F

0

4

d * 0

N

0 I4

N

In

co d 4

9 0 9

0

9

0

9 F

4 I'

0

d 4

0

Ln

rr) 4

Ln

4 N

0

N .

4

Ln F F

0

rr) Ln 4

N

D

co b

0

Ln co N

0

ca rr) 4

c-

i

m N d

m 0 m 0

co N

m w m

m w I'

0

m Tt(

0

4

Ln

rr) 4

rr) N N

0

N 4

F: 0 .d w : a, k 4: k nf a rn c,

5 rn a, k a a, k a

.rf c, U nf a, k 4:

a k 0

.-!-I

a a,

u a, k k 0 u

I

c,

- 23 -

constant value.

O( P) atoms reacted with the OCS, making i t possible to use the

high OCS/03 r a t e as an actinometer.

Thus a t high OCS pressures essentially all of the

3

At large excess of OCS, k1[03] is negligible compared to

k3[OCS] and hence Ia = RCCO} t R(C02}. The quantum yields of

CO and C 0 2 production, @!(CO} and @(C02}, could then be deter-

mined.

Studies were done in which the irradiation time and the

intensity, for otherwise similar conditions, were changed by a

factor of six and nine respectively.

effect on the @(CO} t @(C02}.

time and intensity studies a r e given in Tables 11 and 12 respectively.

These variations showed no

The experimental conditions for the

When ozone i s photolyzed a t the wavelengths used, some

energy exists in excess of that required fo r the dissociation of ozone.

This energy could be in the form of translational energy of the O( P)

atom* If a non-reactive foreign gas is included in the mixture of

O3 and OCS, the O( P) atoms produced by the photolysis of O3 will

lose translational energy through collisions with the foreign gas.

Helium and tetrafluoromethane were used as foreign gases to deter-

mine if this loss of translational energy had any effect on the relative

3

3

ra te constants k / k 1 3 '

The results of the addition of helium were inconclusive

because the points obtained showed considerable scatter and were

not reproducible.

no effect on the relative ra te constants kl/k3.

conditions for the He and CF4 experiments may be found in Tables

13 and 14 respectively.

The addition of CF4 as a foreign gas showed

The experimental

- 24 -

l-4 n

0"

0"

u. u \

n a

u U

d n

0 u Y \

n rd

0 V U

h

n k r r ) k

-, 049

00 cc) N

0

0

0

m 0

0

d

0

0

0 4

co t-

m

c' m 0

d

m 0

00 9 N

0

0

0

co 0

0

l-4

0

0

0 N

co m N

4

0 l-4

l-4

9

N

l-4

d d

m N

rr)

N

d co In 0

9 t? In

0

0 4

t- N

m

e co cc) N

9 00

N

N 0

4

N

4

4

N

In N 9

0

m m * 0

0 N

d N

m 0

9 4

4

d m I+

ca t- d 0

N d N

0

0 9

In *

- 25 -

N 4

El Ll m 4 I3

N 0 N

0

d 4

0

d

* 00 0

d

Ln 9 00

0

- 9 rr)

0

r' * 0

4 0

b-4

4 N

l-0

9 tc cr)

0

0 0

0

N 9 4

0

0

1--(

cr) 0 cr)

0

m * 0

e cz\

d

rn c 3

N

Ln a 9

0

N m a 0

9 9 N

0

m 9

0

9 Ln d

0

* 3 0

N m 4

9 CT

N

N 00 CT

U

9 N d

0

d CT N

0

9 Ln 0

Ln cr)

0

Ln N * 0

00

m N

CT

N

.d c, : a, k 24 k (d a m c,

fi m a, k PI a, k a

- 26 -

cc M

0

rl

0

0

M 0

4

0

4

9 m N

0

Ln N

M

4 0

rl

3 N

N

0

4

0

d 03 Ln

0

r- 9

0

rr) rr)

0

cc 4

rr)

4 0 4

I' I'

N

m d

0

4

0

0

Ln

0 *

0

4

m d * 0

d d rr)

9 d 4

4

0

rr)

Ln cc 4

0

0

0

9

0

0

4

co 0 rr)

0

* d rr)

m rl

4 0

M

N N d 0

M

0

9 0

4

4 M

0

m d 0

4

Ln N

M

rr) N

M

9 co N

cc Ln d 0

0

0

rr) d rl

0 4

00

N

0

rl

m M

4 0

rr)

9 0

M

m Ln -+ 0

9

0

M d 4

co Ln 0

co Ln N

0

m d rr)

rr) rr)

4

9 m N

d 0 .rl c, :

1

a, k A

a k 0 w a a, u a, k k 0 u

c,

JL

G :

l2

-4 c,

a, k 24

Td

d m c,

a, m a, k

k a g

?5

s

0"

.rl c,

a 0 k a

u w 0 a, c, d k

I4 +-.

0" u p: 4-,

- 27 -

co rr) 4

0

F 9 0

0

* 0

co 0

Ln N

0

F rr)

rr)

m 0

rr) 0,

rr)

N N N

0

rr) rr) 0

0

* rr) F

0

m co 0

4 * N

0

* * rr)

4 0

4

m 0

rr)

rr) Ln 9

0

* 3 0

rr) F

4

9 rr) Ln

0

rr) 0 4

0

4 rr)

rr)

d 0

rr)

F m N

rr) 4 co 0

0

0

rr) Ln

N

0

4

F rr) 4

0

rr) 4

rr)

0

co N

4

00

N

k k 0

0 0 rr)

I1

c,

n

2 u U

5 $

1

.VI c,

a, k 24

Td rn c, F: a, rn a, k $34 a, k a

* 28 ..

The present investigation was complicated by a dark reaction

which produced both CO and C02.

produced, R(CO}, in the da rk rans to the R{CO), produced in the

light runswasfound to be less than 10% at OCS pressures less than

approximately 15 torr .

with ozone pressure and with temperature.

CO produced, R{C02}, in the darkruns tothe R{C02}, produced

in the light runs w m found to average approximately 7070, with no

noticeable ozone pressure or temperature effect.

The ratio of the ra te of CO

This ra t io was found to increase slightly

The rat io of the rate of

2

3 Reaction of O( P) Atoms with TMP and OCS

The resul ts of the mercury photosensitized decomposition of

nitrous oxide in the presence of mixtures of 2-trifluorornethylpropene

and carbonyl sulfide in the temperature range 298O-523'KY are

shown in Tables 15-17.

the epoxide E were identified and quantitatively analyzed.

The products CO, N2, the aldehyde A, and

TMP pressures were held approximately constant at 0.7 t o r r

except in a few cases where the pressure was varied between 2 t o r r

and 4.7 to r r .

18.3 tor r , always maintaining a [TMP]/[OCS] ratio between 0.06 and

0.45.

CO production, R{CO}, in the absence of OCS became a significant

factor, and was measured by photolyzing N 2 0 and TMP in the

absence of OCS. The CO produced in the absence of OCS was

generally less than 1570 of the total CO produced with OCS present.

The ratios [N20]/[OCS]> 38 and [N20]/[TMP] > 130 were maintained

to minimize the quenching of mercury by TMP and OCS.

The OCS pressure was varied between 1.4 to r r and

At ratios of [TMP]/[OCS] exceeding this range, the rate of

I

-+ 0

9

0

nl N 0

0

$-I

0

d

0 co d

0 0 Ln

0 r- r- 0

0

0

Ln co 0

0

F N

0

0 m 0

I? 9 N

0

l-l

4

0 m

r- Ln 9

0 co 9

0

r- F

0 0 4

0

0

I

t

-+ 0 N

0

00 0

4

0 Ln

d 00 Ln

Ln N F

0

d 9

r- 4 4

0

N N

0

N m 0

co N

0

4

9 9

N

Ln l-l

N m ln

0 0 N

0

l-l

m N

4

4 9

0

m m 0

Ln -+ 0

m I? t-l

0

4 0

4

m 9 4

0 0 Ln

Ln a3 r- 0

r- m 4

Ln F 4

0

-+ m 0

co -+ 0

Ln 0 N

0

N

F

0 N

0 0 In

w N

m m l-l

N co

0

4

0 m 0

9 d 0

4 m 4

0

0

co

0 4

0 Ln Ln

0 \o r- 0

d -+ m

0 00 $-I

0

9 N

0

4

d 0

d 00

0

4

co 0

4

N Ln

0 0 Ln

0

N

co 0 l-l

r- rn

0

4

d m 0

d d 0

co m 4

0

co 0

4

N

2

d 2l

0 co F

0

9 9

m

N m N

0

F m 0

s 0

m N l-l

0

0

co

Ln N

m N Ln

0 9 F

0

Ln co N

m Ln N

0

9 m 0

t-l Ln

0

m 9 4

0

Ln 0

4

0 N 4

0

9 4

c-- d

m 03 4

- 30

rc,

w w 8

rc,

0 U a w -

c,

!3 u

n h

o f : u -

n - tn o s U b

m 0 m 0

0 Tt(

0

0-l Ln

0

00 m 0

0

* 0

I-l

Ln N N

0 m *

Lo 4 F

0

Pl m 4

Ln N Tt(

0

m m 0

0 9

0

0 00 0

0

rn 4 4

0 N

Ln Ln lrl

Ln N r- 0

m Tt(

I-l

s 0

- 3 1 -

9 4

w 4 4 E-l

a

I

d 0

9

0

Ln r- 0

0

l-4

9

l-4

r- N N

r- 00 In

0 m 9

0

0

0

r- 9 0

0

I' 4

0

9 N

0

dc r- d 0

4

9

4

d N

4 I' Ln

0 d 9

0

9 m CT

I' 0 4

0

P

0

4

d N

0

Ln I' d 0

9

l-4

0 N

m 9 9

Ln Ln 9

0

Ln 0

Ln

CT I+

d

0

CT

0

I-.I

CT N

0

N N dc 0

9

d

0 N

N CT Ln

0 d co 0

N

r-

m CD

0

d

4 m 0

9 m 0

co co N

0

N 9

4

0 d

dc 9 9

0 z 0

9 9

m

2l N

0

dc 0

m Ln

0

0 Ln N

0

9

4

0 N

0 9 9

0 dc 9

0

9 dc N

CT 9 N

0

9 dc 0

9 d 0

N

0

I' Ln

4

Ln M

w r- Ln

u) 0

N

In 9

co

n Lo u 0

4tn

PI c E

Y \

35

U

I-%

0 u 8 L+

I

4 4

0

N co 4

4

4 00

0 N 9

0 1 I-

0

4 0

I- 0 4

0

00 9 ln

0

ln 00

4

0 N

pl

N 9

0 9 r- 0

* Q 9

N 9 4

0

N

ln

0

4

m co 4

ln 4

I- * 9

m m co 0

I- 0

in

ln N

0

ln 9 * 0

9 00

d

ln 4

cr, m Ln

0 m r- 0

i-l 4

rc,

rn N rr)

0

A

0 d 0

9 00

d

Ln 4

I- * 9

ln * I-

0

9 N

N

N -+ 0

4 d rr)

0

I- 00

A

0 nl

I- I- 9

0 0 0

0

d

N

tu N * 0

9 d rn 0

I- 00

4

I- 4

0 ln m

L n 9 9

0

s -4

- 33 -

The absorbed intensity, I was taken equal to the r a t e of a

production of N2.

(pressures based on calibrations at 298OK) with no effect on the

The Ia was varied f rom 1 p,/min to 11.9 p,/min

quantum yield, @{CO}. The irradiation time was varied f rom

15 to 227 minutes with no effect on @{CO}.

The quantum yields of E and A were measured at 298OK and

Examination of Tables 15 and 16 show that all of the O( P) 3 398OK.

atoms reacted either with TMP o r OCS, since the sum of the quantum

yields of A, E, and CO a re , within experimental e r ro r , equal to one.

As the ra t io of [TMP]/[OCS] was increased, the R{CO} decreased.

CHAPTER IV

DISCUSSION

3 Reaction of O( P) Atoms with 0, and OCS

The reaction scheme proposed is:

f 2) 3 O3 t h v + Of P) t O2

o ( ~ P ) ocs - co SO ( 3 )

The SO produced in reaction 3 is known to react rapidly

with 0

3 O( P) atoms being lost to the SO.

to produce SO2 and 02, thus eliminating the possibility of 3

If the previous expression:

is divided through by Iay the following expression for the sum of

the quantum yields of CO and COZY @p(CO) t @{C02) is obtained.

A more convenient expression is obtained by taking the reciprocal,

giving:

- 35 -

A plot of this expression yields a straight line whose slope i s equal

to kl /k3 and whose intercept is equal to one.

pressure and temperature studied a r e shown in Figures 4-10.

Plots a t each ozone

F r o m Figures 9, 11, and 12 it can be seen that kl/k3 is

independent of the absorbed intensity, the irradiation time, and the

addition of a foreign gas.

The relative r a t e constants kl /k3 were found to be independent

of the ozone pressure used.

k l /k3 a t 3 torr and 12 to r r ozone were averaged to obtain the value

at each temperature.

The small differences in the value of

The observed and average values a r e shown in

Table 18.

TABLE 18

OBSERVED VALUES OF kl /k3

197'K 228OK 273OK 299OK

3 tor r O3 1.05 1.05 0.934 0.938

12 tor r O3 0 . 9 2 0.915 0.865

aver age 0.98 1.05 0.925 0.901

An Arrhenius plot of kl /k3 is shown in Figure 13. The points

show considerable scat ter , thus the e r r o r in determining the differ-

ence in activation energy is large, E3 - El = 170 * 70 cal/mole.

However, a large e r r o r would be expected since E

compared to E or E l .

0.671 f .076 .

- El is small 3

The relative pre-exponential factor A1/A3 = 3

.. 36 -

[ { "03) cp + {03}@] I-

- 37 -

" 0

N 0 - a0 W t N O - t - W c

0 -

n vb 0 a m u \ n

0" U

W

I- [(203}0+ {03}@]

- 38 -

Ir) 0 L Y

(u m a

L

,Ob

0 - t cu

d-

M

cu

0

n v) 0 0

n

U

\

0" U

I - [{%}e + {03}e]

- 39 -

t

m

n v) 0 0 N U \ n m 0 I

-

0

[ { l03} BI + {03}@] I-

- 40 -

0 -

\ n

0" L A

t

0

" 5 * O 0,

I@ 0" u. -- u u

I- [{'03} @+ {03)@]

- 41 -

0

I - [{ZOD} o+ {OD}@]

- 42 -

0" t y 0 0 I - m

I- [{203}cp+ {03}@]

- 43 -

L u)

E 0" 'E b y

0 4 4 M

0

+ 0" -u 0 u 8 w

U

0

I- [{%a} 4+ {03}@]

- 44 -

a 4

0 - oo r- (0 In d- M OJ

v)

M

N

0

I- [{%3} @+ {03)@]

- 45 -

u) 0 0 0

lo 0

0 9

- Y

I-

I 0

1

\ - d- 0

0 9

to 0 0

d 0

cp cu cu (0

0 0 0 0 I I I I

9 9 9 9

- 46 - 3 Reaction of O( P) Atoms with TMP and OCS

The reaction scheme proposed is:

Hg t hv (2537A) - H S ( ~ P ~ ) (5)

( 6 ) 3 Hg( P1) t N 2 0 - N2 t O(3P) t Hg

o ( ~ P ) t TMP - A t E (4)

o ( ~ P ) t ocs - co t SO (3)

The reactions listed a r e well known and have been reported

in numerous studies. In reaction 4, A and E represent

2-trifluoromethylpropionaldehyde and 2-trifluoromethylpropylene

oxide respectively. The SO produced in reaction 3 can reac t with

O( P) atoms to produce SO2.

15 and 16 that the sum of the quantum yields of COY A, and E, within

experimental e r r o r , equal one, indicating that O( P) atoms were

not lost to the SO under the conditions studied.

the quantum yields of CO were considerably higher, possibly due to

a complex reaction involving SO, which is known to be removed in

19 wall reactions

3 However, it can be seen from Tables

3

At higher intensities,

The following expression for the [ @ { G O } ] -’ can be derived

from reactions 3-6.

Since CO was produced as a resul t of the photolysis of N 2 0

and TMP in the absence of OCS i t was necessary to make a correction

- 47 -

to the measured quantum yield of CO, @{CO).

calculated, a t each se t of conditions, f rom the measured quantum

yield of CO produced in the absence of OCS and was found to be

generally l e s s than 1570.

resulted in the production of CO and necessitated a second correction

to @ {CO}.

found to equal 1 .7 , by Yarwood, Strausz, and Gunning2' was used

to calculate the quantum yield of 60 produced f rom the quenching

of mercury by OCS. This correction to the measured @,(COJ was

less than 3070 a

The correction w a s

The quenching of mercury by the OCS also

The ratio of quenching cross-sections of OCS and N20,

A plot of the corrected [@(CO)]-l a s a function of [TMP]/[OCS]

yields a straight line with intercept equal to one and a slope equal to

k4/k3. Plots a t 298OK, 398OK, and 523OK a r e shown in Figure 14,

and the observed values of k4/k3 obtained from these plots a r e shown

in Table 19. The relative ra te constants k4/k3 were found to be

independent of the irradiation time and absorbed intensity in the

range of pressures of N 0, TMP, and OCS studied. 2

TABLE 19

OBSERVED VALUES OF k4/k3

k4/k3 Temperature

42.4

18.7

8. 1

- 48 -

t 0

0

- 49 -

An Arrhenius plot of k / k is shown in Figure 15. The points 4 3

fall on a straight line whose slope gives the difference in activation

energy E

pre-exponential factor A4/A3 = 0.928.

expression k - 1.51 x 10 exp(-2220/RT) c m /particle-sec

found by Simonaitis and Heicklen,17 the absolutevalue of k = 1.63 x

The value

- E4 = 2280 cal/mole and whose intercept gives the 3

F r o m these values and the

-11 3 4 -

3 3 exp( -4500/RT) cm /particle-sec was determined.

of k

of k3 in Table 3.

found in this work is compared with previously observed values 3

Determination of the Absolute Value of k,

Since relative r a t e constants k l /k3 were determined, the

absolute value of kl is dependent on the absolute value of k

20 shows the absolute values of k l determined from the relative

pre-exponential factors, A1/A3 = 0.691 f .076, the difference in

activation energy, E j - E l = 170 f 70 cal/mole, and the different

Table 3'

3' observed values of k

TABLE 20

VALUES OF kl CALCULATED FROM

OBSERVED VALUES OF k3

Observed Value of k3 Used 3 k e m /particle-sec) 1

(1.1 f . 2 ) x exp(-4330 *70/RT) This work

(2.12 f .2 ) x 10-11 exp(-4360 *70/RT)

(7.25 f .2 ) x exp(-5330 *70/RT) Homann, Krome and

13 Westenberg and de Haas

14 Wagner

Hoyermann, Wagner and

Wolf rum

(I. 34 f 2) x 10-l' exp(-5630 *70/RT) 15

- 50 -

- 51 -

At any given temperature in the range studied, all of the

Arrhenius expressions for kl yield r a t e constants which a r e in good

agreement with each.other. However, only the Arrhenius expressions

f o r kl calculated from the Westenberg and deHaas value of k

present investigation value of k

reaction 1, which a r e in good agreement with E l determined f rom

the previous collective investigations of k l .

f rom the present investigation of k i s in very good agreement with

the value of E l , determined from the Westenberg and de Haas value

of k39 the Westenberg and de Haas pre-exponential factor is higher

by nearly a factor of two. Since relative ra te constants k /k were

determined in the present investigation, the value of k depends on

the accuracy of the value of k4 which in turn is based on the rate

constant f o r the reaction of &-butene with O( P) atoms.

inaccuracy in the value of k4 or the r a t e constant f o r 1-butene would

be reflected in the accuracy of k found in the present investigation.

On the other hand, Westenberg and de Haas assumed an O/OCS

stoichiometry equal to one, under the conditions of their experiment.

If in fact the stoichiometry was higher, their value of k would be

lower and in closer agreement with the value found in the present

investigation.

and the 3

indicate activation energies, El$ for 3

Although El determined

3’

4 3

3

3 Any

3

3

-11 3 The value of kl = 1.1 x 10 exp(-4330/RT) cm /particle-sec

found in this investigation, provides the best agreement with the

previously obtained collective data for kl .

Arrhenius plot of k determined in the present and previous investi-

gations. exp(-440O/RT)

3 cm e particle-sec was obtained.

Figure 16 shows an

1 11 F r o m this plot the value of kl = 1 . 6 5 ~ 10-

- 52 -

- 53 -

CHAPTER V

SUMMARY

3 In this study the competitive reaction of O( P) atoms with

0 0 and OCS was investigated in the temperature range 197 K - 299OK.

3

The relative ra te constants for the reactions

3 O( P) t o3 - 2 0 2

o ( ~ P ) t ocs - co t SO (3)

were determined and found to be independent of irradiation time,

absorbed intensity, and the addition of a foreign gas.

-11 3 value of k l = 1. 1 x 10

calculated from a pre-determined value of k

3

The absolute

exp(-4330/RT) cm /particle-sec, was

3'

The value of k was determined from a similar competitive

3 study of O( P) atoms with 2-trifluoromethylpropene (TMP) and OCS

in the temperature range 300°K - 523OK. The value k3 = 1.63 x 10 -11

3 exp( -4500/RT) c m /particle-sec, was calculated from the known

rate constant of the O( P) reaction with TMP. 3

The value of kl determined,

the value of k l determined from the

temperature range 300 K - 1150OK. 0

is in excellent agreement with

collective previous works in the

- 54 -

BIBLIOGRAPHY

1. H, K. Paetzold, Chemical Reactions in the Lower and Upper Atmosphere, Chapter 12, Interscience Publishers, New York (1961).

2. V. H. Regener, Physics and Medicine of the Upper Atmosphere, Chapter 8, The Universitv of New Mexico P r e s s . Albuquerque (1952).

3. W. M. Jones andN. Davidson, J. Am. Chem. SOC., d - 84, 2868 (1962).

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

A. Glissman and H. J. Schumacher, Z. Physik. Chem., 21B, 323 (1933).

E. Castellano and H. J. Schumacher, Z. Physik. Chem., - 34, 198 (1962).

-

A. Mathias and H. I. Schiff, Discussions Faraday SOC., 37, 38 (1964). - H. S. Johnston, National Standard Reference Data Ser ies - National Bureau of Standards, No. 20 (1968).

J. S. Calvert and J. N. Pitts, Photochemistry, John Wiley and Sons, Inc. , New York (1966), pp 826.

P. Brix and G. Herzberg, J. Chem. Phys . , - 21, 2240 (1953).

G. Herzberg, Spectra of Diatomic Molecules, 2nd Ed. , D. van Nostrand Co. , Inc., New York (1950).

JANAF Thermochemical Data, The Dow Chemical Co., Midland, Michigan ( 196 1).

J. S. Calvert and J. N. P i t t s , Photochemistry, John Wi ley and Sons, Inc., New York (1966), pp 209.

A. A. Westenberg and N. deHaas, J. Chem. Phys., - 50, 707 (1969).

K. Hoyermann, H.Ggn Wagner, and J. Wolfrum, Ber. - Bunsenges. physik. Chem. , - 7 1, 603 (1967).

K. H. Homann, G. Krome and H. Gg. Wagner, Ber. Bunsenges. physik. Chem. , - 72, 998 (1968).

S. J. Moss and K. R. Jennings, Trans. Faraday S O C . , 3_ 64, 686 (1968).

- 55 -

17. R. Simonaitis and J. P. Heicklen, J. Chem. Phys. , in press .

18.

19. W. Wood, Unpublished resul ts at The Pennsylvania State

R, J. Cventanoviz, J. Chem. Phys. , - 23, 1208 (1954).

University (1970).

20. A. J. Yarwood, 0. P. Strausz, andH. E. Gunning, J. Chem. Phys. , 41, 1705 (1964).