<s>
In	O
nuclear	O
magnetic	O
resonance	O
spectroscopy	O
and	O
magnetic	O
resonance	O
imaging	O
,	O
the	O
Ernst	B-Algorithm
angle	I-Algorithm
is	O
the	O
flip	B-Algorithm
angle	I-Algorithm
(	O
a.k.a.	O
</s>
<s>
Consider	O
a	O
single	O
pulse	O
sequence	O
consisting	O
of	O
(	O
1	O
)	O
an	O
excitation	O
pulse	O
with	O
flip	B-Algorithm
angle	I-Algorithm
,	O
(	O
2	O
)	O
the	O
recording	O
of	O
the	O
time	O
domain	O
signal	O
(	O
Free	O
induction	O
decay	O
,	O
FID	O
)	O
for	O
a	O
duration	O
known	O
as	O
acquisition	O
time	O
,	O
and	O
(	O
3	O
)	O
a	O
delay	O
until	O
the	O
next	O
excitation	O
pulse	O
(	O
here	O
called	O
interpulse	O
delay	O
)	O
.	O
</s>
<s>
If	O
the	O
longitudinal	B-Algorithm
relaxation	I-Algorithm
time	I-Algorithm
of	O
the	O
specific	O
spin	O
in	O
question	O
is	O
short	O
compared	O
to	O
the	O
sum	O
of	O
and	O
,	O
the	O
spins	O
(	O
or	O
the	O
spin	O
ensembles	O
)	O
are	O
fully	O
or	O
close	O
to	O
fully	O
relaxed	O
.	O
</s>
<s>
Then	O
a	O
90°	O
flip	B-Algorithm
angle	I-Algorithm
will	O
yield	O
the	O
maximum	O
signal	O
intensity	O
(	O
or	O
signal-to-noise	O
ratio	O
)	O
per	O
number	O
of	O
averaged	O
FIDs	O
.	O
</s>
<s>
This	O
signal	O
loss	O
can	O
be	O
minimized	O
by	O
reducing	O
the	O
flip	B-Algorithm
angle	I-Algorithm
.	O
</s>
<s>
The	O
optimal	O
signal-to-noise	O
ratio	O
for	O
a	O
given	O
combination	O
of	O
longitudinal	B-Algorithm
relaxation	I-Algorithm
time	I-Algorithm
and	O
delay	O
between	O
excitation	O
pulses	O
is	O
obtained	O
at	O
the	O
Ernst	B-Algorithm
angle	I-Algorithm
:	O
</s>
<s>
For	O
example	O
,	O
to	O
obtain	O
the	O
highest	O
signal-to-noise	O
ratio	O
for	O
a	O
signal	O
with	O
set	O
to	O
match	O
the	O
signal	O
's	O
,	O
the	O
optimal	O
flip	B-Algorithm
angle	I-Algorithm
is	O
68°	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
calculated	O
Ernst	B-Algorithm
angle	I-Algorithm
may	O
apply	O
only	O
to	O
the	O
selected	O
one	O
of	O
the	O
many	O
signals	O
in	O
the	O
spectrum	O
and	O
other	O
signals	O
may	O
be	O
less	O
intense	O
than	O
at	O
their	O
own	O
Ernst	B-Algorithm
angle	I-Algorithm
.	O
</s>
