In this slide:- An

1
In this slide-


An abstract to begin
this review
Total of 51 slides and Show time 50mins
From Molecule to Materials with HR PMR in Solids
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This work originated when the measurements of
shielding tensor (by HR PMR methods) in Organic
Molecular single crystals indicated that at a
proton site of a given molecule can have
significant induced field contributions from the
adjascent molecules particularly when the
neighboring molecules contain aromatic rings with
high magnetic susceptibilities. The calculations
of intermolecular contributions provoked to
extend the lattice sum procedure for regions
beyond the Inner Spherical Volume element (the
conventionally known Lorentzs sphere) and these
considerations resulted in a summation procedure
extendable over the entire macroscopic specimen,
which is a much more convenient alternative to
the usual integration procedures for calculating
the demagnetization factors.
S.Aravamudhan, Department
of Chemistry, North
Eastern Hill University, http//www.nehu.ac.in/
PO NEHU Campus,
Mawkynroh Umshing Shillong 793022
Meghalaya INDIA
2
Bulk Susceptibility Effects
In HR PMR
SOLIDS
Liquids
Induced Fields at the Molecular Site
Single Crystal Spherical Shape
Single crystal arbitray shape
Da - 4?/3
Db 2?/3
Sphere
Lorentz
cavity
3
1. Experimental determination of Shielding
tensors by HR PMR techniques in single
crystalline solid state, require Spherically
Shaped Specimen. The bulk susceptibility
contributions to induced fields is zero inside
spherically shaped specimen.
2. The above criterion requires that a semi micro
spherical volume element is carved out around the
site within the specimen and around the specified
site this carved out region is a cavity which is
called the Lorentz Cavity. Provided the Lorentz
cavity is spherical and the outer specimen shape
is also spherical, then the criterion 1 is valid.
3. In actuality the carving out of a cavity is
only hypothetical and the carved out portion
contains the atoms/molecules at the lattice sites
in this region as well. The distinction made by
this hypothetical boundary is that all the
materials outside the boundary is treated as a
continuum. For matters of induced field
contributions the materials inside the Lorentz
sphere must be considered as making discrete
contributions.
Illustration in next slide depicts pictorially
the above sequence
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/index.html
4
1. Contributions to Induced Fields at a POINT
within the Magnetized Material.
High Resolution Proton Magnetic Resonance
Experiment
Only isotropic bulk susceptibility is implied in
this presentation
II
I
Sphere sII0
Calculate sI and subtract from sexp
PROTON
SHIELDING sexp
Molecular sM Region I sI Region II sII
sexp sI sM sII
- sI
Lorentz Sphere Contribution
sI sinter
Bulk Susceptibility Effects
5
1. Contributions to Induced Fields at a POINT
within the Magnetized Material.
The Outer Continuum in the Magnetized Material
Sphere of
Lorentz
Specified Proton Site
Lorentz Sphere
Lorentz Cavity
The Outer Continuum in the Magnetized Material
Inner Cavity surface Din
Outer surface D out
In the NEXT Slide Calculation Using Magnetic
Dipole Model Equation
D out - Din Hence D out Din 0
The various demarcations in an Organic Molecular
Single Crystalline Spherical specimen required to
Calculate the Contributions to the induced
Fields at the specified site. D out/in values
stand for the corresponding Demagnetization
Factors
6
EUROMAR2008
If P is related to Emac (instead of to ELoc in
equation-2) which is the applied field, then the
paradoxical situation would not be posed. The
paradox is that ELoc is a field which is a value
including the effect of P, and hence to know ELoc
for equation 2 the value of P must have been
known already.
http//nehuacin.tripod.com/id5.html
In equation 1 above ELoc on the Left Hand Side of
the equation, obviously depends on the value of P
for estimation. And, in equation 2, the value for
to is to be estimated from the value of ELoc.
7
E3 is the discrete sum at the center of the
spherical cavity does not depend upon
macroscopic specimen shape. (Lorentz field)
E2 is usually for only a spherical Inner Cavity
with Demagnetization factor0.33 E2 NINNER
or DINNER x P E1 is the contribution
assuming the uniform bulk susceptibility and
depend upon outer shape E1 NOUTER or DOUTER x
P E0 is the externally applied field
E3 intermolecular
EUROMAR2008
E2 Ninner x P
http//nehuacin.tripod.com/id5.html
E1Nouter x P
C.Kittel, book on Solid State Physics Pages
405-409
Lorentz Relation Eloc E0 E1 E2 E3
8
Magnetic Field
6.0E-08
Each moment contributes to induced field
2 A equal spacing
Benzene Molecule Its magnetic moment
?M . (1-3.COS2?)/(RM)3
9
(1-3.cos2?) term causes ve -ve contributing
zones See drawing below
summation
Lattice
Shell by Shell
Induced field varies as R-3
Number of molecules in successive
shells increase as R2
Magnetic Field
Product of above two vary as R-1
Each moment contributes to induced field
The above distance dependences can be depicted
graphically
Dashed lines convergence limit
2 A equal spacing
Benzene Molecule Its magnetic moment
When the R becomes large, the R-1 term
contribution becomes smaller and smaller to
become insignificant
-ve zone
?M . (1-3.COS2?)/(RM)3
ve
Magnetic field direction
10
INDUCED FIELDS,DEMAGNETIZATION,SHIELDING
Induced Field inside a hypothetical Lorentz
cavity within a specimen H  Shielding Factor
? Demagnetization Factor
Da  H - ? . H0 - 4 . ? . (Din- Dout)a .
? . H0
out
?
These are Ellipsoids of Revolution and the three
dimensional perspectives are imperative
in
? 4 . ? . (Din- Dout)a . ?
When inner outer shapes are spherical
polar axis a
Din Dout
m a/b
Induced Field H 0
equatorial axis b
Induced Field / 4 . ? . ? . H0 0.333 -
Dellipsoid
Thus it can be seen that the the D-factor value
depends only on that particular enclosing-surface
shape innner or outer
? b/a
polar axis b
References to ellipsoids are as per the Known
conventions--------?gtgtgtgt?
equatorial axis a
11
2. Calculation of induced field with the Magnetic
Dipole Model using point dipole approximations.
Induced field Calculations using these equations
and the magnetic dipole model have been simple
enough when the summation procedures were applied
as would be described in this presentation.
Isotropic Susceptibility Tensor

sinter
s1
s2
s3 . .

12
How to ensure that all the dipoles have been
considered whose contributions are signifiicant
for the discrete summation ? That is, all the
dipoles within the Lorentz sphere have been taken
into consideration completely so that what is
outside the sphere is only the continuum regime.
The summed up contributions from within Lorentz
sphere as a function of the radius of the sphere.
The sum reaches a Limiting Value at around 50Aº.
These are values reported in a M.Sc., Project
(1990) submitted to N.E.H.University. T.C. stands
for (shielding) Tensor Component
Thus as more and more dipoles are considered for
the discrete summation, The sum total value
reaches a limit and converges. Beyond this,
increasing the radius of the Lorentz sphere does
not add to the sum significantly
13
Within Cubic Lattice Spherical Lorentz region
Lattice Constant Varied 10-9.5
Eventhough the Variation of Convergence value
seems widely different as it appears on Y-axis,
these are within 1.5E-08 hence practically no
field at the Centre
"http//aravamudhan-s.ucoz.com/amudhan_nehu/graphp
resent.html "
14
Till now the convergence characteristics were
reported for Lorentz Spheres, that is the inner
semi micro volume element was always spherical,
within which the discrete summations were
calculated. Even if the outer macro shape of the
specimen were non-spherical (ellipsoidal) it has
been conventional only to consider inner Lorentz
sphere while calculating shape dependent
demagnetization factors.
Would it be possible to Calculate such trends for
summing within Lorentz Ellipsoids ?
a
3rd Alpine Conference on SSNMR (Chamonix) poster
contents Sept 2003.
YES
b
Outer a/b1 outer
a/b0.25 Demagf0.33
Demagf0.708 inner a/b1
inner a/b1 Demagf-0.33
Demagf-0.33 0.33-0.330
0.708-0.330.378 conventional combinations of
shapes Fig.5a


Conventional cases
Current propositions of combinations Outer a/b1
outer a/b0.25 Demagf0.33
Demagf0.708 inner a/b0.25
inner a/b0.25 Demagf-0.708
Demagf-0.708 0.33-0.708-0.378 0.708-0.7080
Fig.5b

15
Zero Field Convergence
The shape of the inner volume element was
replaced with that of an Ellipsoid and a similar
plot with radius was made as would be depicted
Ellipticity Increases
Within Cubic Lattice Ellipsoidal Lorentz region
Lattice Constant Varied 10-9.5
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resent.html "
16
RECAPITULATION on TOPICS in SOLID STATE
Defining what is Conventionally known as Lorentz
Sphere
It becomes necessary to define an Inner Volume
Element I.V.E in most of the contexts to
distinguish the nearest neighbours (Discrete
Region) of a specified site in solids, from the
farther elements which can be clubbed in to be a
continuum. The shape of the I.V.E. had always
been preferentially (Lorentz) sphere. But, in the
contexts to be addressed hence forth the I.V.E.
need not be invariably a sphere. Even ellipsoidal
I.V.E. or any general shape has to be
considered and for the sake of continuity of
terms used it may be referred to as Lorentz
Ellipsoids / Lorentz Volume Elements. It has to
be preferred to refer to hence forth as I.V.E.
( Volume element inside the solid material
small compared to macroscopic sizes and large
enough compared to molecular sizes and
intermolecular distances).
I.V.E. need not be invariably a sphere
general shape
Currently The Discrete
Region
Conventional
Lorentz Spheres
I.V.E. Shapes other than spherical
For any given shape
For outer shapes
OR
arbitrary
Spherical
cubical
ellipsoidal
OR
OR
17
2. Calculation of induced field with the Magnetic
Dipole Model using point dipole approximations
rs
?v Volume Susceptibility
r
V Volume (4/3) ? rs3
2
1
?v -2.855 x 10-7 rs/r 45.8602C
?1 ?2 2.4 x 10-11 for ?0
18
      
"http//aravamudhan-s.ucoz.com/amudhan_nehu/3rd_Al
pine_SSNMR_Aram.html"
3rd Alpine Conference On SSNMR results from
Poster
19
Bulk Susceptibility Contribution 0
sexp sinter sintra
Discrete Summation Converges in Lorentz Sphere to
sinter
Bulk Susceptibility Contribution 0 Similar to
the spherical case. And, for the inner ellipsoid
convergent sinter is the same as above
sexp (ellipsoid) should be sexp (sphere)
HR PMR Results independent of shape for the above
two shapes !!
20
The questions which arise at this stage
1. How and Why the inner ellipsoidal element has
the same convergent value as for a spherical
inner element?
2. If the result is the same for a ellipsoidal
sample and a spherical sample, can this lead to
the further possibility for any other regular
macroscopic shape, the HR PMR results can become
shape independent ?
This requires the considerations on
The Criteria for Uniform Magnetization depending
on the shape regularities. If the resulting
magnetization is Inhomogeneous, how to set a
criterian for zero induced field at a point
within on the basis of the Outer specimen shape
and the comparative inner cavity shape?
21
The reason for considering the Spherical Specimen
preferably or at the most the ellipsoidal shape
in the case of magnetized sample is that only for
these regular spheroids, the magnetization of
(the induced fields inside) the specimen are
uniform. This homogeneous magnetization of the
material, when the sample has uniformly the same
Susceptibility value, makes it possible to
evaluate the Induced field at any point within
the specimen which would be the same anywhere
else within the specimen. For shapes other than
the two mentioned, the resulting magnetization of
the specimen would not be homogeneous even if the
material has uniformly the same susceptibity
through out the specimen.
Calculating induced fields within the specimen
requires evaluation of complicated integrals,
even for the regular spheroid shapes (sphere and
ellipsoid) of specimen
22
Thus if one has to proceed further to inquire
into the field distributions inside regular
shapes for which the magnetization is not
homogeneous, then there must be simpler procedure
for calculating induced fields within the
specimen, at any given point within the specimen
since the field varies from point to point, there
would be no possibility to calculate at one
representative point and use this value for all
the points in the sample.
A rapid and simple calculation procedure slides
22 to 28 could be evolved and as a testing
ground, it was found to reproduce the
demagnetization factor values with good accuracy
which compared well with the tabulated values
available in the literature.
In fact, the effort towards this step wise
inquiry began with the realization of the simple
summation procedure for calculating
demagnetization factor values.
Results presented at the 2nd Alpine Conference on
SSNMR, Sept. 2001 http//saravamudhan.tripod.com/

23
2. Calculation of induced field with the Magnetic
Dipole Model using point dipole approximations.
Induced field Calculations using these equations
and the magnetic dipole model have been simple
enough when the summation procedures were applied
as described in the previous presentations and
expositions.
Isotropic Susceptibility Tensor

24
2. Calculation of induced field with the Magnetic
Dipole Model using point dipole approximations
For the Point Dipole Approximation to be valid
practical criteria had been that the ratio r
rS 101
Ri ri 10 1 or even better and the ratio
Ri / ri C can be kept constant for all the
n spheres along the line (radial vector)
n th
?i will be the same for all i , i 1,n and the
value of n can be obtained from the equation
below
1st
With C Ri / ri , i1,n
3. Summation procedure for Induced Field
Contribution within the specimen from the bulk of
the sample.
25
Description of a Procedure for Evaluating the
Induced Field Contributions from the Bulk of the
Medium
Radial Vector with polar coordinates r, ?, f.
(Details to find in 4th Alpine Conference on
SSNMR presentation Sheets 6-8) http//nehuacin.tri
pod.com/id1.html
26
For a given ? and ?, Rn and R1 are to be
calculated and using the formula
n along that vector can be calculated with a
set constant C and the equation below indicates
for a given ? and ? this n?,? multiplied by the
?i? ?? being the same for all ?would give
the total cotribution from that direction
?i?
?? ?i 1,n?,? ?i? n?,? x ?i?
27
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28
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29
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05_icmrbs.html"
30
A spherical sample is to have a homogeneously


zero induced field within the specimen.
Because of the convenience with which the
summation

procedure can be applied
to find the value of


induced field not only at the center but also at


any point within the specimen, it
has been possible

to
calculate the trend for the variation of induced
field from the centre to the near-surface points.
There is parabolic trend observable and this
seems to be the possible trend in most of the
cases of inhomogeneous field distributions as
well except for the values of the parabola
describing this trend. It seems possible to
derive parabolic parameter values depending on
the shape factors in the case of inhomogeneous
field distributions in the non-ellipsoidal
shapes. This would greatly reduce the necessity
to do the summing over all the ? and f
values. This possiblility has been illustrate
(in anticipation of the verification of the
trends) in the remaining presentation in
particular the last four slides.
31
Using the Summation Procedure induced fields
within specimen of TOP (Spindle) shape and
Cylindrical shape could be calculated at various
points and the trends of the inhomogeneous
distribution of induced fields could be
ascertained.
Poster Contribution at the 17thEENC/32ndAmpere,
Lille, France, Sept. 2004
Graphical plot of the Results of Such Calculation
would be on display
Zero ind. Field Points
32
The top or a Spindle Shaped object comes under
the category of Shapes within which the Induced
field distribution would be Inhomogeneous even if
the Susceptibility is uniformly the same over the
entire sample
NMR Line for only Intra molecular Shielding
Added intermolecular Contribultions causes a
shift downfield or upfield
homogeneous
Inhomogeneous Magnetization can Cause Line shape
alterations
4. The case of Shape dependence for homogeneously
magnetized sample, and consideration of
in-homogeneously magnetized material.
33
The induced field distribution in materials which
inherently possess large internal magnetic
fields, or in materials which get magnetized when
placed in large external Magnetic Fields, is of
importance to material scientists to adequately
categorize the material for its possible uses. It
addresses to the questions pertaining to the
structure of the material in the given state of
matter by inquiring into the details of the
mechanisms by which the materials acquire the
property of magnetism. To arrive at the required
structural information ultimately, the beginning
is made by studying the distribution of the
magnetic field distributions within the material
(essentially magnetization characteristics) so
that the field distribution in the neighborhood
of the magnetized (magnetic) material becomes
tractable. The consequences external to the
material due the internal magnetization is the
prime concern in finding the utilization
priorities for that material. In the materials
known conventionally as the magnetic materials,
the internal fields are of large magnitude. To
know the magnetic field inducing mechanisms to a
greater detail it may be advantageous to study
the trends and patterns with a more sensitive
situation of the smaller variations in the
already small values of induced fields can be
studied and the Nuclear Magnetic Resonance
Technique turns out to be a technique, which
seems suitable for such studies. When the
magnetization is homogeneous through out the
specimen, it is a simple matter to associate a
demagnetization factor for that specimen with a
given shape-determining factor. When the
magnetized (magnetic) material is
in-homogeneously magnetized, then a single
demagnetization factor for the entire specimen
would not be attributable but only point wise
values. Then can an average demagnetization
factor be of any avail and how can such average
demagnetization factor be defined and calculated
.It is a tedious task to evaluate the
demagnetization factor for homogeneously
magnetized, spherical (ellipsoidal) shapes. An
alternative convenient mathematical procedure
could be evolved which reproduces the already
available tables of values with good accuracy.
With this method the questions pertaining to
induced field calculations and the inferences
become more relevant because of the feasibility
of approaches to find answers.
34
Correlating r and r -3
Calculation of the Induced Field Distribution in
the region outside the magnetized spherical
specimen
35
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36
http//aravamudhan-s.ucoz.com/amudhan20012000/isma
r_ca98.html
37
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38
Advantages of the summation method described in
the previous sheets (An alternative method for
demagnetization factor calculation) Also at
http//www.geocities.com/inboxnehu_sa/nmrs2005_icm
rbs.html 1.     First and Foremost, it was a
very simple effort to reproduce the
demagnetization factor values, which were
obtained and tabulated in very early works on
magnetic materials. Those Calculations which
could yield such Tables of demagnetization factor
values were rather complicated and required
setting up elliptic integrals which had to be
evaluated. 2.     Secondly, the principle
involved is simply the convenient point dipole
approximation of the magnetic dipole. And, the
method requires hypothetically dividing the
sample to be consisting of closely spaced spheres
and the radii of these magnetized spheres are
made to hold a convenient fixed ratio with their
respective distances from the specified site at
which point the induced fields are calculated.
This fixed ratio is chosen such that for all the
spheres the point dipole approximation would be
valid while calculating the magnetic dipole field
distribution. 3.     The demagnetization factors
have been tabulated only for such shapes and
shape factors for which the magnetization of the
sample in the external magnetic field is uniform
when the magnetic susceptibility of the material
is the same homogeneously through out the sample.
This restricts the tabulation to only to the
shapes, which are ellipsoids of rotation. Where
as, if the magnetization is not homogeneous
through out the sample, then, there were no such
methods possible for getting the induced field
values at a point or the field distribution
pattern over the entire specimen. The present
method provides a greatly simplified approach to
obtain such distributions. 4.     It seems it is
also a simple matter, because of the present
method, to calculate the contributions at a given
site only from a part of the sample and account
for this portion as an independent part from the
remaining part without having to physically cause
any such demarcations. This also makes it
possible to calculate the field contribution from
one part of the sample, which is within itself a
part with homogeneously, magnetized part and the
remaining part being another homogeneously
magnetized part with different magnetization
values. Hence a single specimen which is
inherently in two distinguishable part can each
be considered independently and their independent
contribution can be added.  For the point 1
mentioned above view
Calculation of Induced Fileds Outside the specimen
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http//saravamudhan.tripod.com/
39
The task would be to calculate the induced field
inside the cavity scavity
Organic Molecular single crystal a specimen of
arbitrary shape
Induced field calculation by discrete summation
sinter
I.V.E Sphere
Continuum
sIVE sinter sM
Discrete
I.V.E. Cavity
Added sinter Shifts the line position
O
scavity sBulk sM
Inner Volume Element I.V.E
H
O
MRSFall2006
sintra / sM
O
O
4 point star indicates the molecule at a central
location. Structure of a typical molecule on the
right
sIVE(S)
sM
O
H
In-homogeneity can cause line shape alterations
O
Proton Site with sintra
not simply shifts only
single sharp line
40
A cylinder shaped specimen (Blue line in the plot
below)
The points on the Blue line would be specified
and at these Calculated field values an NMR line
would be placed after adding the sum total of
intra and intermolecular contributions to induced
fields.
Calculations at 9 points along the axis
Zero ind. Field Points
Not to be discussed in this presentation
Distance along the axis
MRSFall2006 http//nehuacin.tripod.c
om/id1.html
41
Only inter-molecular value 5.80E-07 was added
and the line shape was plotted with those values
NEXT GRAPHICAL PLOT
A Graph of the data in table
Cylinder Cylinder
By Calculation Trend line interpolation
7 -2.87E-07 -2.9E-07
6 -1.9E-07
5 -1.87E-07 -1E-07
4 3.25E-08 -2.8E-08
3 2.8E-08
2 6.45E-08 6.8E-08
1 9.2E-08
0 9.35E-08 1E-07
-1 9.2E-08
-2 6.45E-08 6.8E-08
-3 2.8E-08
-4 3.25E-08 -2.8E-08
-5 -1.87E-07 -1E-07
-6 -1.9E-07
-7 -2.87E-07 -2.9E-07
Overlapping last three lines
Lines at interpolated values
Only inter molecular value 5.80E-07 can be set 0
No intra molecular Value inter- molecular value
(in I.V.E) set0 in subsequent plots only cavity
field is used to generate line shapes
42
Same graph as displayed in previous slide
Gradual increase of component lines broadens the
lines and can cause the change in the appearance
of overall shape. Illustration with 4 different
width values
10 times that of red Width 2.5 times that
of green
Width twice that of blue
Width twice that of red
Same width as above
43
Line at sIVE
44
1.Reason for the conevergence value of the
Lorentz sphere and ellipsoids being the same.
Added Results to be discussed at 4th Alpine
Conference
http//nehuacin.tripod.com/id3.html
2.Calculation of induced fields within magnetized
specimen of regular shapes. (includes other-than
sphere and ellipsoid cases as well)
3. Induced field calculations indicate that the
point within the specimen should be specified
with relative coordinate values. The independent
of the actual macroscopic measurements, the
specified point has the same induced field value
provided for that shape the point is located
relative to the standardized dimension of the
specimen. Which means it is only the ratios are
important and not the actual magnitudes of
distances.
Further illustrations in next slide
The two coinciding points of macroscopic specimen
and the cavity are in the respective same
relative coordinates. Hence the net induced field
at this point can be zero
These two points would have the same induced
field values (both at ¼)
These two points would have the same induced
field values (both midpoints)
Lorentz cavity
45
Symbols for Located points
Applying the criterion of equal magnitude
demagnetization factor and opposite sign
Inside the cavity
Points in the macroscopic specimen
This type of situation as depicted in these
figures for the location of site within the
cavity at an off-symmetry position, raises
certain questions for the discrete summation and
the sum values. This is considered in the next
slide
? specimen length
? cavity length
In the cavity the cavity point is relatively at
the midpoint of cavity. The point in bulk
specimen is relatively at the relative ¼ length.
Hence the induced field contributions cannot be
equal and of opposite sign
Relative coordinate of the cavity point and the
Bulk specimen point are the same. Hence net
induced field can be zero
46
For a spherical and ellipsoidal inner cavity, the
induced field calculations were carried out at a
point which is a center of the cavity .
In all the above inner cavities, the field was
calculated at a point which is centrally
placed in the inner cavity. Hence the discrete
summation could be carried out about this point
of symmetry.
This is the aspect which will have to be
investigated from this juncture onwards after the
presentation at the 4th Alpine Conference. The
case of anisotropic bulk susceptibility can be
figured out without doing much calculations
further afterwards.
If the point is not the point of symmetry, then
around this off-symmetry position the discrete
summation has to be calculated. The consequence
of such discrete summation may not be the same as
what was reported in 3rd Alpine conference for
ellipsoidal cavities, but centrally placed points.
47
This stage of the Report was possible because of
the beginning made as early as 1979-80 to be
concerned with the Induced field distributions
inside the specimen in connection with the HR PMR
in Single Crystal solids. A careful consideration
of the demagnetization Calculations the results
of which had been reported in the form of
documented tables revealed that a pattern can be
setup with a simplified form but the question was
how to translate this criteria in the form of a
concrete mathematical equations. An intense
effort (which could have elicited a comment as a
futile effort from active researchers in the
related area) did result in a form for the
equation, the derivation of which turned out to
be requiring only four to five elementary steps.
Equipped with this formulation and equation in
hand it did not take any more than half an hour
to one hour to arrive at the Zero Induced field
value at the centre of the Lorentz Cavity in a
spherically shaped magnetized specimen. Then it
was a question of arriving at the reported
numerical values for the ellipsoids of different
shape-factor ratios the 'm' and the 'µ'
(reciprocal of 'm') . It took about one month to
incorporate the ellipsoidal equation criteria and
get a few reported demagnetization factors. All
this could be achieved by simple hand
calculations - not even a pocket calculator to
use. http//nehuacin.tripod.com/pre_euromar_compil
ation/id5.html This was the result in hand as
early as 1984. Afterwards,since there were not
many who would have wanted to know about these (
because the demagnetization factors were already
available in Tables since long before), the
results were stored as they were in a scribbling
pad filled with numbers due to the hand
calculations. By that time all the references
which have been gathered (these are all listed
out in the website http//saravamudhan.tripod.com,
in the page for the '2nd Alpine conference on
SSNMR' CLICK on this pane to display the
webpage)indicated that a reference( 17) in the
Physical review publication from authors from
Washington, St Louis Missourie,USA had some what
similar effort reported.
48
What was referred to before is a publication by
an Indian author who worked and submitted a
dissertation at E.T.H., Zurich, Switzerland. This
work had been also published in Pure and Applied
Geophysics. I had tried to get the referred issue
from the Geophysical Research Institute at
Hyderabad and I mentioned about this to
Dr.A.C.Kunwar at IICT, Hyderabad, as early as
1995-96. By that time I had been at the North
Eastern Hill University, shillong as Lecturer in
Chemistry and as excercises to M.Sc., students I
had suggested these simple equations and
susceptibility induced fields in magnetized
specimen to work for their 6-months project
report successively for about 4-5 years. This
resulted in a computer program to calculate these
induced field contributions and 6 project reports
consisted of consecutive materials. There was
not much interest from any to these equations and
results, presumably, even at that time in my
opinion which could be because all the
demagnetization factors are well reported and,
whether now it is simplified calculation or
not,it is merely a question of simplification but
the possible values were already well
documented.After about two years in 1998 I
received by POST the reprint of the publication
by P.V.Sharma (in Geophysical Research journal)
from Dr.A.C. Kunwar. This paper contained a rapid
computation method for such calculations and my
considerations were even simpler. And hence from
the NMRS symposium at Dehradun in 1999, I have
been presenting my consideration by way of
Poster/oral presentations and the support I had
for presenting them has resulted in this kind of
a activity requiring them to be reported in
International Conferences. During the period till
now these efforts had encouragements from the
NMRS, ISMAR and the Congress Ampere and
occasional finacial support from these organizers
and the Funding agencies CSIR, INSA have gone a
long way in pusrsuing the efforts with the
possible provisions at the North Eastern Hills
University, which is gratefully acknowledged
49
IBS Meeting Symposium at BHU, 2010
Prof. S. Aravamudhan, receiving a memento after
Chairing a technical session
From Prof. P.C.Mishra Convener, IBS 2010
50
International Biophysics Conference IUPAB. At
Buenos Aires, Argentina April-May 2002
S.Aravamudhan and K.Akasaka IBS Meeting 2002,
CBMR, SGPGIMS, Lucknow
Amitabha Chattopadhyaya
NR Krishana
A generous grant from the WELCOME TRUST UK
enabled the participation of Dr.S.Aravamudhan in
the International Biophysics Conference at
Buenos Aires, Argentina which is gratefully
acknowledged.
51
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13nsc_nmrs2011.html
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