A visualisation as to what could happen when there is NO chosen direction relevant and relatable to the SPIN AXIS

1
Quantization of
Nuclear Spin Components
An
Animated Illustration
Spin Axis may be along the chosen axis also
When an axis is defined
But no Quantization requirements for the
Components of Spin
A visualisation as to what could happen when
there is NO chosen direction relevant and
relatable to the SPIN AXIS
No well defined direction for the spin axis
specified outside the spinning nucleus?
When an Axis is defined
Spin Axis
Components of Spin Vector can be quantized
Spinning nucleus
Spin Vector Component in the presence of a chosen
axis is quantized and has fixed orientation
Nucleus has mass M
What is the Interaction by which a direction can
be specified as relatable to the quantization
that manifests?
2
For the Quantization Effects on the Spin Angular
Momentum in presence of External magnetic
Field VIEW the power point file on LARMOR
PRECESSION.ppt Linked at section III.1 on the
line precession in Magnetic Fields at
URL- http//geocities.com/saravamudhan1944/inno_c
ourse_contents.html
A RED ARROW (the z component) can be
representative and indicate the presence of the
magnetic moment.
Total (resultant) Nuclear Magnetic Moment
Z-Component
XY Component
3
NET Magnetization in Magnetic Field
Now more such arrows are depicted to indicate the
randomness of these vector directions -all arrows
in red color nowThe vectors add up to zero
A Completed-Picture of aligned Spins (?) --- Not
yet (!)
The individual magnetic moment vectors are
oriented independent of others. Hence a random
orientation is depicted
When a STEADY external strong magnetic Field is
turned on then these magnetic moment vectors
(components) all get aligned along the LINE of
the magnetic field direction in time of the order
of longitudinal relaxation time
Some of the Vectors will be oriented opposite to
the Field Direction as it would be known later.
But more will be along the Field and, a NET
Magnetization along the magnetic field RESULTS
4
When the Magnetic Field is applied
The previous slide tried to illustrate the
salient aspects to be noted in the final picture
for the magnetization growth. In this effort the
time sequences of the spin alignments for the
growth of the magnetization have not been shown
realistically. The alignment of the spins
parallel to the field direction was depicted to
precede the alignment in the direction opposite
to that of the field direction. In reality it
would be hard to identify before hand which spin
would get aligned after which other spins and
whether this particular spin would align parallel
to or opposite to the magnetic field direction.
The final picture would have to depict more
parallel alignment of the spins than the
alignment opposite.
Before applying the magnetic field the spins are
in a state of random distribution of the
orientation
The alignment of the spins is effected and the
alignment results in a NET magnetization along
the Magnetic Field Direction
5
Magnetization Strength
GROWTH
Time
6
Relaxation Longitudinal and transverse
I h
NET Magnetization
Longitudinal T1 Relaxation
Transverse T2 Relaxation
Randomization in XY plane
p/2 pulse