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ClOOCl

ClOOCl, also written Cl2O2, is the chlorine monoxide dimer, a reactive, intermediate species in stratospheric ozone chemistry. It consists of two ClO units connected by an O–O bond and is formed when two ClO radicals combine.

Formation and photochemistry: In the gas phase, ClO radicals recombine to form ClOOCl via ClO + ClO →

Role in ozone depletion: The ClOOCl dimer acts as a reservoir for chlorine in the stratosphere. Its

Detection and significance: ClOOCl is detected in the atmosphere by spectroscopic methods from satellites, balloons, and

See also: Ozone depletion, ClO radical, chlorine-catalyzed ozone destruction cycles.

ClOOCl.
Under
sunlight,
ClOOCl
absorbs
solar
radiation
and
photolyzes
to
yield
two
ClO
radicals:
ClOOCl
+
hv
→
2
ClO.
This
photodissociation
regenerates
reactive
chlorine
monoxide
and
closes
a
subset
of
catalytic
cycles
that
destroy
ozone.
formation
stores
reactive
chlorine
as
ClOOCl,
and
its
daylight
photolysis
releases
ClO,
feeding
the
catalytic
destruction
cycle
of
ozone
that
involves
ClO,
O3,
and
related
species.
The
chemistry
of
ClOOCl
is
especially
relevant
to
polar
stratospheric
regions
during
spring,
when
sunlight
returns
and
ozone
loss
accelerates.
ground-based
instruments.
Its
absorption
of
light
in
the
near-UV
and
visible
ranges
enables
its
photolysis
in
daytime
conditions.
Laboratory
studies
of
its
photolysis
rates
and
reactions
are
used
to
improve
atmospheric
models
of
ozone
depletion
and
to
understand
the
timing
and
magnitude
of
chlorine-catalyzed
ozone
loss.