chemical physics of discharges - Argonne National Laboratory

+
The drop in 0
with 0 by charge exchange.
2
40
with increasing pressure may be due to the fact that 0' can react
+ +
0 +02 -4 o2 + o
This would account for the drop in 0' intensity at conditions at which N+ (which
cannot un ergo loss by charge exchange) remains constant. In the same pressure
9
range, O2 drops in intensity to about the same extent as does N +, which can
disappear by charge exchange with N. 2(
In a mass spectrometer ion chamber 0 + and 04+ are found in rather smell in-
3
tensities, apparently formed by the reactions:
--f +* +
0; 2Tu +02 c o4 -3 o3 + o
+*
04 + o2 + 04+ + o2
The latter is very faint, however. The ionization potential of 0 is slightly
greater than that of O2 (100,101), so O3 can react with 0 as fo?lows:
2
o3 + + o2 + 0,' + o3
(19)
(100) J. T. Herron and H. I. Schiff, 2. Chem. Phys. 24, 1266 (1956)
-
(101) R. K. Curran, 2. Chem. Phys. 35, 1849 (1961) -
+
No doubt this accounts for the failure to observe O3 .
~ ~~
~ -~
The absence of 0; may be
merely a matter of sensitivity. t
In our laboratory we have also studied the ions formed in a microwave discharge
in a mixture of nitrogen and oxygen at a constart pressure of about 0.1 To r,
AS+
might be expected, the intensities of Npf and N decreased and those of 0: and 0
kngreased as the proportion of nitrogen decreased and that of oxygen increased.
NO was very intense ovfr th$ range $f 10% to 75% oxygen in the m xture.+ This is
not surprising, since N , 4
N2 and N, reqcting with 0 or 0 and 0 and 0 reacting
with N or N are capable of producing NO .
and no doubg is ionized by electron impact.
(16)
Further, &O is produced in ghe discharge
+
Small amounts o f NO2 ions were observed in all of the mixtures studied, and
small amounts of N 0 were found in the nitrogen rich mixtures, but disappeared
2
when the proportion of nitrogen in the mixture dropped below 75%. The manner of
their formation is not known, but from their very small intensity we infer that they
are probably formed by third order processes. It is surprising that no N: ion was
observed when oxygen was present. Presumably it is capable of reacting in several
ways with 0 or 0, and so is destroyed as fast as it is formed. The system OZ-N2
2
is of great interest and will be studied further.
This research was supported by Project SQUID of the Navy, under Grant NOM
3623 S-21, which we acknowledge with gratitude.
1
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