DOC.
14 99
This is the
well-known
Stokes' rule.
It should
be especially
emphasized
that,
according
to
our
conception,
at
weak
illumination the
produced amount
of
light
must
be
proportional
to
the
intensity
of the exciting
light, because
each exciting
energy quantum
will
induce
an
elementary
process
of
the kind indicated
above, independent
of the
action
of
the other
exciting
energy
quanta.
In particular,
no
lower
limit
will exist for the
intensity
of
the
exciting
light
below which
the light
would
[34]
be
unable
to act
as
an
exciter
of
light.
According
to
the
conception
of the
phenomena
expounded,
deviations
from
Stokes' rule
are
conceivable
in
the
following
cases:
[35]
1.
When
the
number
of
simultaneously
converting
energy
quanta
per
unit
volume
is
so
large
that
an
energy
quantum
of the
light
produced
could obtain
its
energy
from
several
producing
quanta;
2.
When
the
producing
(or
produced)
light
does not have
the
same energy
properties that obtain for
"black-body
radiation" within the
range
of validity
of
Wien's
law
as,
for
example,
when
the
exciting
light is
produced
by a body
of
such
high
temperature
that
Wien's
law
is
no
longer
valid for the
pertinent
wavelength.
The
latter possibility deserves
special
attention, for
according
to
the
conception
expounded
above
it
is
not impossible
that
even
in
great
dilutions
the
energetic
behavior
of
a
"non-Wien
radiation" differs
from
that of
a
"black-body
radiation" that
is
within the
range
of
validity
of
Wien's
law.
§8.
On
the
generation of
cathode
rays
by
illumination
of
solid bodies
The
usual
conception,
that the
energy
of light is
continuously
dis-
tributed
over
the
space
through
which
it travels,
meets
with
especially
great
difficulties
when
one
attempts
to
explain
the
photoelectric
phenomena;
these
difficulties
are
presented
in
a
pioneering work
by
Mr.
Lenard.1
According
to
the
conception
that the
exciting
light consists
of
energy
quanta
of
energy
(R/N)ßv,
the
production
of cathode
rays
by
light
can
be
conceived
in
the
following
way.
The body's
surface layer is penetrated
by
1P.
Lenard,
Ann.
d.
Phys.
8
(1902):
169
and
170.
[37]
[36]