98 HEURISTIC
VIEW
OF
LIGHT
-oo
*
0
-
%
av6e dv
1
I
CO
00
•
0
N
o
"
wav
6
T
dv
If, with
regard
to
the
dependence
of
its
entropy
on
volume,
a mono-
chromatic radiation
(of
sufficiently
low density)
behaves
like
a
discontinuous
medium
consisting
of
energy
quanta
of
magnitude
Rßv/N,
then it
seems
reasonable
to investigate whether
the
laws of
generation and
conversion
of
light
are
also
so
constituted
as
if
light
consisted
of such
energy quanta.
We
will
now
consider this
question.
§7.
On
Stokes' rule
Let monochromatic
light
be
converted
by
photoluminescence
to
light
of
another
frequency, and
let
us assume
in
accordance
with the
result
just
obtained that both the
producing and
the
produced
light
consist
of
energy
quanta
of
magnitude (R/N)ßv,
where
v
denotes the
pertinent
frequency. The
conversion
process
is then
to be
interpreted
as
follows.
Each
producing
energy quantum
of
frequency
v1
is absorbed
and-at least at
a
sufficiently
low
distribution
density of
the
producing
energy
quanta-by
itself
gives
rise
to
the
generation
of
a
light
quantum
of
frequency
v2;
possibly
the
absorption
of
the
producing
light
quantum
might
also
be
accompanied
by
the simultaneous
generation of
light
quanta
of
frequencies v3, v4, etc.,
as
well
as
of
energy
of
some
other kind (e.g., heat). It
makes
no
difference
by
what
kind
of
intermediary
processes
this
end
result is mediated.
If
the
photoluminescent
substance is
not to
be regarded
as
a
permanent
source
of
energy,
then,
according
to
the
energy
principle,
the
energy
of
a
produced energy quantum
cannot
be greater
than that
of
a
producing
light
quantum;
hence
we
must
have
or
R
n
R
n
N
ßv2
i
1
ßvl
'
[32]
[33]