<s>
Resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
(	O
RR	O
spectroscopy	O
)	O
is	O
a	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
technique	O
in	O
which	O
the	O
incident	O
photon	B-Application
energy	O
is	O
close	O
in	O
energy	O
to	O
an	O
electronic	O
transition	O
of	O
a	O
compound	O
or	O
material	O
under	O
examination	O
.	O
</s>
<s>
The	O
frequency	O
coincidence	O
(	O
or	O
resonance	B-Application
)	O
can	O
lead	O
to	O
greatly	O
enhanced	O
intensity	O
of	O
the	O
Raman	B-Architecture
scattering	I-Architecture
,	O
which	O
facilitates	O
the	O
study	O
of	O
chemical	O
compounds	O
present	O
at	O
low	O
concentrations	O
.	O
</s>
<s>
Raman	B-Architecture
scattering	I-Architecture
is	O
usually	O
extremely	O
weak	O
,	O
since	O
only	O
about	O
1	O
in	O
10	O
million	O
photons	B-Application
that	O
hit	O
a	O
sample	O
are	O
scattered	O
with	O
a	O
loss	O
(	O
Stokes	B-Algorithm
)	O
or	O
gain	O
(	O
anti-Stokes	O
)	O
in	O
energy	O
from	O
changes	O
in	O
vibrational	O
energy	O
of	O
the	O
molecules	O
in	O
the	O
sample	O
;	O
the	O
rest	O
of	O
the	O
photons	B-Application
are	O
scattered	O
with	O
no	O
change	O
in	O
energy	O
.	O
</s>
<s>
Resonance	B-Application
enhancement	O
of	O
Raman	B-Architecture
scattering	I-Architecture
requires	O
the	O
incident	O
wavelength	O
(	O
usually	O
from	O
a	O
laser	O
)	O
to	O
be	O
close	O
to	O
that	O
of	O
an	O
electronic	O
transition	O
of	O
the	O
molecules	O
.	O
</s>
<s>
Raman	B-Algorithm
spectroscopy	I-Algorithm
and	O
RR	O
spectroscopy	O
provide	O
information	O
about	O
the	O
vibrations	O
of	O
molecules	O
,	O
and	O
can	O
also	O
be	O
used	O
for	O
identifying	O
unknown	O
substances	O
.	O
</s>
<s>
Infrared	O
spectroscopy	O
involves	O
measuring	O
the	O
direct	O
absorption	O
of	O
photons	B-Application
with	O
the	O
appropriate	O
energy	O
to	O
excite	O
molecular	O
bond	O
vibrational	O
modes	O
and	O
phonons	O
.	O
</s>
<s>
The	O
wavelengths	O
of	O
these	O
photons	B-Application
lie	O
in	O
the	O
infrared	O
region	O
of	O
the	O
spectrum	O
,	O
hence	O
the	O
name	O
of	O
the	O
technique	O
.	O
</s>
<s>
Raman	B-Algorithm
spectroscopy	I-Algorithm
measures	O
the	O
excitation	O
of	O
bond	O
vibrations	O
by	O
an	O
inelastic	O
scattering	O
process	O
,	O
in	O
which	O
the	O
incident	O
photons	B-Application
are	O
more	O
energetic	O
(	O
usually	O
in	O
the	O
visible	O
,	O
ultraviolet	O
or	O
even	O
X-ray	B-Library
region	O
)	O
and	O
lose	O
(	O
or	O
gain	O
in	O
the	O
case	O
of	O
anti-Stokes	B-Algorithm
Raman	I-Algorithm
scattering	I-Algorithm
)	O
only	O
part	O
of	O
their	O
energy	O
to	O
the	O
sample	O
.	O
</s>
<s>
The	O
two	O
methods	O
are	O
complementary	O
because	O
some	O
vibrational	O
transitions	O
that	O
are	O
observed	O
in	O
IR	O
spectroscopy	O
are	O
not	O
observed	O
in	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
,	O
and	O
vice	O
versa	O
.	O
</s>
<s>
RR	O
spectroscopy	O
is	O
an	O
extension	O
of	O
conventional	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
that	O
can	O
provide	O
increased	O
sensitivity	O
to	O
specific	O
(	O
colored	O
)	O
compounds	O
that	O
are	O
present	O
at	O
low	O
concentrations	O
(	O
micro	O
to	O
millimolar	O
)	O
in	O
an	O
otherwise	O
complex	O
mixture	O
of	O
compounds	O
.	O
</s>
<s>
An	O
advantage	O
of	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
over	O
(	O
normal	O
)	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
is	O
that	O
the	O
intensity	O
of	O
bands	O
can	O
be	O
increased	O
by	O
several	O
orders	O
of	O
magnitude	O
.	O
</s>
<s>
Such	O
a	O
molecule	O
can	O
be	O
excited	O
to	O
a	O
higher	O
vibrational	O
mode	O
through	O
the	O
direct	O
absorption	O
of	O
a	O
photon	B-Application
of	O
the	O
appropriate	O
energy	O
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
observe	O
molecular	O
vibrations	O
by	O
an	O
inelastic	O
scattering	O
process	O
,	O
Stokes	B-Algorithm
Raman	B-Architecture
scattering	I-Architecture
being	O
one	O
such	O
process	O
.	O
</s>
<s>
A	O
photon	B-Application
is	O
absorbed	O
and	O
then	O
re-emitted	O
(	O
scattered	O
)	O
with	O
lower	O
energy	O
.	O
</s>
<s>
The	O
difference	O
in	O
energy	O
between	O
the	O
absorbed	O
and	O
re-emitted	O
photons	B-Application
corresponds	O
to	O
the	O
energy	O
required	O
to	O
excite	O
a	O
molecule	O
to	O
a	O
higher	O
vibrational	O
mode	O
.	O
</s>
<s>
Anti-Stokes	B-Algorithm
Raman	I-Algorithm
scattering	I-Algorithm
is	O
another	O
inelastic	O
scattering	O
process	O
and	O
only	O
occurs	O
from	O
molecules	O
starting	O
in	O
excited	O
vibrational	O
states	O
;	O
it	O
results	O
in	O
light	O
scattered	O
with	O
higher	O
energy	O
.	O
</s>
<s>
Light	O
scattered	O
elastically	O
(	O
no	O
change	O
in	O
energy	O
between	O
the	O
incoming	O
photons	B-Application
and	O
the	O
re-emitted/scattered	O
photons	B-Application
)	O
is	O
known	O
as	O
Rayleigh	O
scattering	O
.	O
</s>
<s>
A	O
Raman	B-Algorithm
spectrum	I-Algorithm
is	O
generated	O
by	O
plotting	O
the	O
intensity	O
of	O
the	O
scattered	O
light	O
versus	O
.	O
</s>
<s>
Like	O
infrared	O
spectroscopy	O
,	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
can	O
be	O
used	O
to	O
identify	O
chemical	O
compounds	O
because	O
the	O
values	O
of	O
are	O
indicative	O
of	O
different	O
chemical	O
species	O
(	O
their	O
so-called	O
chemical	O
fingerprint	O
)	O
.	O
</s>
<s>
Thus	O
,	O
armed	O
with	O
a	O
database	O
of	O
spectra	O
from	O
known	O
compounds	O
,	O
one	O
can	O
unambiguously	O
identify	O
many	O
different	O
known	O
chemical	O
compounds	O
based	O
on	O
a	O
Raman	B-Algorithm
spectrum	I-Algorithm
.	O
</s>
<s>
Not	O
all	O
vibrational	O
transitions	O
are	O
Raman	O
active	O
,	O
meaning	O
that	O
some	O
vibrational	O
transitions	O
do	O
not	O
appear	O
in	O
the	O
Raman	B-Algorithm
spectrum	I-Algorithm
.	O
</s>
<s>
In	O
contrast	O
to	O
IR	O
spectroscopy	O
,	O
where	O
a	O
transition	O
can	O
only	O
be	O
seen	O
when	O
that	O
particular	O
vibration	O
causes	O
a	O
net	O
change	O
in	O
dipole	O
moment	O
of	O
the	O
molecule	O
,	O
in	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
only	O
transitions	O
where	O
the	O
polarizability	O
of	O
the	O
molecule	O
changes	O
along	O
the	O
vibrational	O
coordinate	O
can	O
be	O
observed	O
.	O
</s>
<s>
This	O
is	O
the	O
fundamental	O
difference	O
in	O
how	O
IR	O
and	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
access	O
the	O
vibrational	O
transitions	O
.	O
</s>
<s>
In	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
,	O
the	O
incoming	O
photon	B-Application
causes	O
a	O
momentary	O
distortion	O
of	O
the	O
electron	O
distribution	O
around	O
a	O
bond	O
in	O
a	O
molecule	O
,	O
followed	O
by	O
re-emission	O
of	O
the	O
radiation	O
as	O
the	O
bond	O
returns	O
to	O
its	O
normal	O
state	O
.	O
</s>
<s>
Hence	O
,	O
in	O
a	O
centrosymmetric	O
molecule	O
,	O
IR	O
and	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
are	O
mutually	O
exclusive	O
.	O
</s>
<s>
In	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
,	O
the	O
wavelength	O
of	O
the	O
incoming	O
photons	B-Application
coincides	O
with	O
an	O
electronic	O
transition	O
of	O
the	O
molecule	O
or	O
material	O
.	O
</s>
<s>
Electronic	O
excitation	O
of	O
a	O
molecule	O
results	O
in	O
structural	O
changes	O
which	O
are	O
reflected	O
in	O
the	O
enhancement	O
of	O
Raman	B-Architecture
scattering	I-Architecture
of	O
certain	O
vibrational	O
modes	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
Tsuboi	O
's	O
rule	O
,	O
which	O
gives	O
a	O
qualitative	O
relationship	O
between	O
the	O
nature	O
of	O
an	O
electronic	O
transition	O
and	O
the	O
enhancement	O
pattern	O
in	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
.	O
</s>
<s>
There	O
are	O
two	O
primary	O
methods	O
used	O
to	O
quantitatively	O
understand	O
resonance	B-Application
Raman	O
enhancement	O
.	O
</s>
<s>
The	O
selective	O
enhancement	O
of	O
the	O
Raman	B-Architecture
scattering	I-Architecture
from	O
specific	O
modes	O
under	O
resonance	B-Application
conditions	O
means	O
that	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
is	O
especially	O
useful	O
for	O
large	O
biomolecules	O
with	O
chromophores	O
embedded	O
in	O
their	O
structure	O
.	O
</s>
<s>
In	O
such	O
chromophores	O
,	O
the	O
resonance	B-Application
scattering	O
from	O
charge-transfer	O
(	O
CT	O
)	O
electronic	O
transitions	O
of	O
the	O
metal	O
complex	O
generally	O
result	O
in	O
enhancement	O
of	O
metal-ligand	O
stretching	O
modes	O
,	O
as	O
well	O
as	O
some	O
of	O
the	O
modes	O
associated	O
with	O
the	O
ligands	O
alone	O
.	O
</s>
<s>
The	O
Raman	B-Algorithm
spectrum	I-Algorithm
of	O
a	O
protein	O
containing	O
perhaps	O
hundreds	O
of	O
peptide	O
bonds	O
but	O
only	O
a	O
single	O
porphyrin	O
molecule	O
may	O
show	O
only	O
the	O
vibrations	O
associated	O
with	O
the	O
porphyrin	O
.	O
</s>
<s>
The	O
main	O
advantage	O
of	O
RR	O
spectroscopy	O
over	O
non-resonant	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
is	O
the	O
large	O
increase	O
in	O
intensity	O
of	O
the	O
bands	O
in	O
question	O
(	O
by	O
as	O
much	O
as	O
a	O
factor	O
of	O
106	O
)	O
.	O
</s>
<s>
This	O
is	O
in	O
stark	O
contrast	O
to	O
non-resonant	O
Raman	O
spectra	O
,	O
which	O
usually	O
requires	O
concentrations	O
greater	O
than	O
0.01	O
M	O
.	O
RR	O
spectra	O
usually	O
exhibit	O
fewer	O
bands	O
than	O
the	O
non	O
resonant	O
Raman	B-Algorithm
spectrum	I-Algorithm
of	O
a	O
compound	O
,	O
and	O
the	O
enhancement	O
seen	O
for	O
each	O
band	O
can	O
vary	O
depending	O
on	O
the	O
electronic	O
transitions	O
with	O
which	O
the	O
laser	O
is	O
resonant	O
.	O
</s>
<s>
The	O
instrumentation	O
used	O
for	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
is	O
identical	O
to	O
that	O
used	O
for	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
;	O
specifically	O
,	O
a	O
highly	O
monochromatic	O
light	O
source	O
(	O
a	O
laser	O
)	O
,	O
with	O
an	O
emission	O
wavelength	O
in	O
either	O
the	O
near-infrared	O
,	O
visible	O
,	O
or	O
near-ultraviolet	O
region	O
of	O
the	O
spectrum	O
.	O
</s>
<s>
the	O
color	O
)	O
varies	O
widely	O
from	O
compound	O
to	O
compound	O
,	O
wavelength-tunable	O
lasers	O
,	O
which	O
appeared	O
in	O
the	O
early	O
1970s	O
,	O
are	O
useful	O
as	O
they	O
can	O
be	O
tuned	O
to	O
coincide	O
with	O
an	O
electronic	O
transition	O
(	O
resonance	B-Application
)	O
.	O
</s>
<s>
The	O
spectra	O
obtained	O
contain	O
non-resonant	O
Raman	B-Architecture
scattering	I-Architecture
of	O
the	O
matrix	O
(	O
e.g.	O
,	O
solvent	O
)	O
also	O
.	O
</s>
<s>
Sample	O
handling	O
in	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
offers	O
considerable	O
advantages	O
over	O
FTIR	O
spectroscopy	O
in	O
that	O
glass	O
can	O
be	O
used	O
for	O
windows	O
,	O
lenses	O
,	O
and	O
other	O
optical	O
components	O
.	O
</s>
<s>
A	O
further	O
advantage	O
is	O
that	O
whereas	O
water	O
absorbs	O
strongly	O
in	O
the	O
infrared	O
region	O
,	O
which	O
limits	O
the	O
pathlengths	O
that	O
can	O
be	O
used	O
and	O
masking	O
large	O
region	O
of	O
the	O
spectrum	O
,	O
the	O
intensity	O
of	O
Raman	B-Architecture
scattering	I-Architecture
from	O
water	O
is	O
usually	O
weak	O
and	O
direct	O
absorption	O
interferes	O
only	O
when	O
near-infrared	O
lasers	O
(	O
e.g.	O
,	O
1064nm	O
)	O
are	O
used	O
.	O
</s>
<s>
When	O
resonance	B-Application
Raman	O
spectra	O
are	O
recorded	O
,	O
however	O
,	O
sample	O
heating	O
and	O
photo-bleaching	O
can	O
cause	O
damage	O
and	O
a	O
change	O
to	O
the	O
Raman	B-Algorithm
spectrum	I-Algorithm
obtained	O
.	O
</s>
<s>
Furthermore	O
,	O
if	O
the	O
absorbance	O
of	O
the	O
sample	O
is	O
high	O
(	O
>	O
OD	O
2	O
)	O
over	O
the	O
wavelength	O
range	O
in	O
which	O
the	O
Raman	B-Algorithm
spectrum	I-Algorithm
is	O
recorded	O
then	O
inner-filter	O
effects	O
(	O
reabsorption	O
of	O
the	O
Raman	B-Architecture
scattering	I-Architecture
by	O
the	O
sample	O
)	O
can	O
decrease	O
signal	O
intensity	O
dramatically	O
.	O
</s>
<s>
The	O
laser	O
beam	O
can	O
be	O
at	O
any	O
angle	O
with	O
respect	O
to	O
the	O
optical	O
axis	O
used	O
to	O
collect	O
Raman	B-Architecture
scattering	I-Architecture
.	O
</s>
<s>
The	O
collected	O
scattered	O
radiation	O
is	O
focused	O
into	O
a	O
spectrograph	O
,	O
in	O
which	O
the	O
light	O
is	O
first	O
collimated	O
and	O
then	O
dispersed	O
by	O
a	O
diffraction	O
grating	O
and	O
refocused	O
onto	O
a	O
CCD	B-Algorithm
camera	I-Algorithm
.	O
</s>
<s>
Use	O
of	O
this	O
(	O
or	O
equivalent	O
)	O
equipment	O
and	O
following	O
an	O
appropriate	O
protocol	O
can	O
yield	O
better	O
than	O
10%	O
repeatability	O
in	O
absolute	O
measurements	O
for	O
the	O
rate	O
of	O
Raman	B-Architecture
scattering	I-Architecture
.	O
</s>
<s>
This	O
can	O
be	O
useful	O
with	O
resonance	B-Application
Raman	O
for	O
accurately	O
determining	O
optical	O
transitions	O
in	O
structures	O
with	O
strong	O
Van	O
Hove	O
singularities	O
.	O
</s>
<s>
Resonance	B-Application
hyper-Raman	O
spectroscopy	O
is	O
a	O
variation	O
on	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
in	O
which	O
the	O
aim	O
is	O
to	O
achieve	O
an	O
excitation	O
to	O
a	O
particular	O
energy	O
level	O
in	O
the	O
target	O
molecule	O
of	O
the	O
sample	O
by	O
a	O
phenomenon	O
known	O
as	O
two-photon	O
absorption	O
.	O
</s>
<s>
In	O
two-photon	O
absorption	O
,	O
two	O
photons	B-Application
are	O
simultaneously	O
absorbed	O
into	O
a	O
molecule	O
.	O
</s>
<s>
When	O
that	O
molecule	O
relaxes	O
from	O
this	O
excited	O
state	O
to	O
its	O
ground	O
state	O
,	O
only	O
one	O
photon	B-Application
is	O
emitted	O
.	O
</s>
<s>
In	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
,	O
certain	O
parts	O
of	O
molecules	O
can	O
be	O
targeted	O
by	O
adjusting	O
the	O
wavelength	O
of	O
the	O
incident	O
laser	O
beam	O
to	O
the	O
“	O
color	O
”	O
(	O
energy	O
between	O
two	O
desired	O
electron	O
quantum	O
levels	O
)	O
of	O
the	O
part	O
of	O
the	O
molecule	O
that	O
is	O
being	O
studied	O
.	O
</s>
<s>
This	O
is	O
known	O
as	O
resonance	B-Application
fluorescence	O
,	O
hence	O
the	O
addition	O
of	O
the	O
term	O
“	O
resonance	B-Application
”	O
to	O
the	O
name	O
“	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
”	O
.	O
</s>
<s>
Some	O
excited	O
states	O
can	O
be	O
achieved	O
via	O
single	O
or	O
double	O
photon	B-Application
absorption	O
.	O
</s>
<s>
In	O
these	O
cases	O
,	O
however	O
,	O
the	O
use	O
of	O
double	O
photon	B-Application
excitation	O
can	O
be	O
used	O
to	O
attain	O
more	O
information	O
about	O
these	O
excited	O
states	O
than	O
would	O
a	O
single	O
photon	B-Application
absorption	O
.	O
</s>
<s>
There	O
are	O
some	O
limitations	O
and	O
consequences	O
to	O
both	O
resonance	B-Application
Raman	O
and	O
resonance	B-Application
hyper	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
.	O
</s>
<s>
Both	O
resonance	B-Application
Raman	O
and	O
resonance	B-Application
hyper	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
employ	O
a	O
tunable	O
laser	O
.	O
</s>
<s>
Regular	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
,	O
therefore	O
,	O
is	O
only	O
sensitive	O
to	O
the	O
electron	O
energy	O
transitions	O
that	O
match	O
that	O
of	O
the	O
laser	O
used	O
in	O
the	O
experiment	O
.	O
</s>
<s>
The	O
molecular	O
parts	O
that	O
can	O
be	O
studied	O
by	O
normal	O
resonance	B-Algorithm
Raman	I-Algorithm
spectroscopy	I-Algorithm
is	O
therefore	O
limited	O
to	O
those	O
bonds	O
that	O
happen	O
to	O
have	O
a	O
“	O
color	O
”	O
that	O
fits	O
somewhere	O
into	O
the	O
spectrum	O
of	O
“	O
colors	O
”	O
to	O
which	O
the	O
laser	O
used	O
in	O
that	O
particular	O
device	O
can	O
be	O
tuned	O
.	O
</s>
<s>
Resonance	B-Application
hyper	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
,	O
on	O
the	O
other	O
hand	O
,	O
can	O
excite	O
atoms	O
to	O
emit	O
light	O
at	O
wavelengths	O
outside	O
the	O
laser	O
’s	O
tunable	O
range	O
,	O
thus	O
expanding	O
the	O
range	O
of	O
possible	O
components	O
of	O
a	O
molecule	O
that	O
can	O
be	O
excited	O
and	O
therefore	O
studied	O
.	O
</s>
<s>
Resonance	B-Application
hyper	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
is	O
one	O
of	O
the	O
types	O
of	O
“	O
non-linear	O
”	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
.	O
</s>
<s>
In	O
linear	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
,	O
the	O
amount	O
of	O
energy	O
that	O
goes	O
into	O
the	O
excitation	O
of	O
an	O
atom	O
is	O
the	O
same	O
amount	O
that	O
leaves	O
the	O
electron	O
cloud	O
of	O
that	O
atom	O
when	O
a	O
photon	B-Application
is	O
emitted	O
and	O
the	O
electron	O
cloud	O
relaxes	O
back	O
down	O
to	O
its	O
ground	O
state	O
.	O
</s>
<s>
This	O
is	O
due	O
to	O
the	O
fact	O
that	O
the	O
energy	O
input	O
in	O
hyper-Raman	O
spectroscopy	O
is	O
much	O
larger	O
than	O
that	O
of	O
typical	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
.	O
</s>
<s>
Non-linear	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
tends	O
to	O
be	O
more	O
sensitive	O
than	O
conventional	O
Raman	B-Algorithm
spectroscopy	I-Algorithm
.	O
</s>
<s>
In	O
the	O
X-ray	B-Library
region	O
,	O
enough	O
energy	O
is	O
available	O
for	O
making	O
electronic	O
transitions	O
possible	O
.	O
</s>
<s>
At	O
core	O
level	O
resonances	B-Application
,	O
X-ray	B-Library
Raman	B-Architecture
scattering	I-Architecture
can	O
become	O
the	O
dominating	O
part	O
of	O
the	O
X-ray	B-Library
fluorescence	O
spectrum	O
.	O
</s>
<s>
This	O
type	O
of	O
scattering	O
is	O
also	O
known	O
as	O
Resonant	O
inelastic	O
X-ray	B-Library
scattering	O
(	O
RIXS	O
)	O
.	O
</s>
<s>
In	O
the	O
soft	O
X-ray	B-Library
range	O
,	O
RIXS	O
has	O
been	O
shown	O
to	O
reflect	O
crystal	O
field	O
excitations	O
,	O
which	O
are	O
often	O
hard	O
to	O
observe	O
with	O
any	O
other	O
technique	O
.	O
</s>
<s>
For	O
certain	O
wide	O
band	O
materials	O
such	O
as	O
graphite	B-Application
,	O
RIXS	O
has	O
been	O
shown	O
to	O
(	O
nearly	O
)	O
conserve	O
crystal	O
momentum	O
and	O
thus	O
has	O
found	O
use	O
as	O
a	O
complementary	O
bandmapping	O
technique	O
.	O
</s>
