11
B.
Cuvettes
The
turret
6
holds
standard
10
x
10
mm
cuvettes
with
outside
dimensions
of
12.5
x
12.5
mm.
A
metal
clip
is
used
to
push
each
cuvette
into
one
of
the
corners
of
its
individual
space
for
reproducible
positioning
and
to
favor
temperature
transfer.
Walls
of
the
turret
body
are
relieved
to
prevent
scratching
of
the
optical
surfaces
of
the
cuvette.
Cuvettes
should
be
45
mm
or
taller,
otherwise
they
will
be
difficult
to
recover
from
the
cuvette
holders.
C.
Cuvette
z
‐
Height
The
“z
height”
of
a
cuvette
is
the
distance
between
the
bottom
surface
of
the
cuvette
and
the
designed
position
for
the
optical
center
line,
where
the
incident
beam
of
light
strikes
the
cuvette.
The
z
height
for
cuvettes
in
the
turret
6
is
15
mm.
Figure
6.
The
z
height
of
a
typical
microcuvette
D.
Cooling
Water
for
the
Peltier
The
Peltier
element
(or
“thermoelectric
cooler”)
is
a
heat
pump.
When
cooling,
it
transfers
heat
from
the
turret
body
to
a
heat
exchanger;
when
heating,
electrical
polarity
is
reversed
and
it
transfers
heat
from
the
heat
exchanger
to
the
tower.
When
cooling,
it
is
particularly
important
to
transfer
this
heat
away
from
the
Peltier.
This
is
accomplished
with
flowing
water
through
the
heat
exchanger.
A
source
of
water
(or
other
cooling
fluid)
must
be
connected
to
the
⅛‐
inch
hose
barbs
on
the
front
of
the
turret
6
.
This
can
be
done
with
the
BATH
10
,
which
is
provide
with
the
turret
6. The
BATH
10
consists
of
a
submersible
aquarium
pump,
the
appropriate
fittings
for
connecting
tubing,
and
a
plastic
bucket.
Connect
the
pump
to
the
turret
6
,
place
it
in
the
bucket
with
water,
and
run
a
return
tube
to
the
bucket.
You
may
also
provide
the
cooling
water
from
another
source,
such
as
a
refrigerated
cooling
bath
or
even
a
tap
for
brief
use.
You
will
need
a
flow
rate
of
100
‐
300
ml/minute.
This
flow
should
require
a
pressure
of
about
3
‐
5
psi
(0.2
‐
0.3
bar).
Do
not
exceed
an
input
water
pressure
of
25
psi
(1.7
bar),
as
damage
may
occur
inside
the
turret
6
.
The
heat
exchanger
and
hose
barbs
are
brass,
and
the
tubing
inside
the
turret
6
is
silicone.
Be
sure
that
any
circulating
fluid
used,
other
than
water,
will
not
degrade
these
materials.
The
temperature
of
the
heat
exchanger
in
the
turret
6
is
monitored
using
a
thermistor.
If
the
temperature
exceeds
60
°C,
then
temperature
control
is
shut
down
to
prevent
damage
to
the
Peltier
