Evidence from several sources suggest possible
in situ production of N
2
O in
the stratosphere. Considering that solar photoabsorption
provides a large stratospheric source of
O
2
(A
3
Σ
u
+
),
and since vibrational levels of v
![[gt-or-equal]](https://www.rsc.org/images/entities/char_2a7e.gif)
6 are
primarily removed by N
2
, the
O
2
(A
3
Σ
u
+
)+N
2
system is studied to determine whether it is
an atmospherically significant N
2
O source. Using
243–250 nm photoexcitation to produce vibrationally
excited
O
2
(A
3
Σ
u
+
,
v=7–10), and frequency modulation diode laser
spectroscopy as the detector of N
2
O, we examine
the products generated in a closed cell. We thereby set an
upper limit of 0.002% on the N
2
O yield for the
process, and conclude that stratospheric N
2
O
production by this route is not significant compared to
existing ground-based sources. The stability of
N
2
O in an
N
2
O–O
3
–N
2
mixture subjected to prolonged 245 nm radiation is also
studied. For low levels of O
3
(10 ppm) and
N
2
O (40–90 ppb), no loss of N
2
O
is observed.