Polarized Light Scattering Topic 3 Part 3 Biophysics.
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Transcript of Polarized Light Scattering Topic 3 Part 3 Biophysics.
![Page 1: Polarized Light Scattering Topic 3 Part 3 Biophysics.](https://reader033.fdocuments.us/reader033/viewer/2022051516/56649f175503460f94c2d22d/html5/thumbnails/1.jpg)
Polarized Light Scattering
Topic 3 Part 3
Biophysics
![Page 2: Polarized Light Scattering Topic 3 Part 3 Biophysics.](https://reader033.fdocuments.us/reader033/viewer/2022051516/56649f175503460f94c2d22d/html5/thumbnails/2.jpg)
More rigorous Treatment of Light Scattering
rEdVe)kk1(r
ekrE)r(E V
rkirki2
0��
.ˆˆ ..
• This is not a solution
•Polarizability per unt volume is a tensor (matrix)
• Transversality is ensured by k̂k1�
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First Born and coupled dipole approximation
• The first born approximation assumes the electric field inside the particle is equal to the incident electric field.
• The coupled dipole approximation
'
..
.''V
0V
rkkirki2
s EredVr
ek)r(E o
�
jjN
1j
jrkirki2
s Eer
ekr(E
�
.) ..
ijijjjijjjN
ijij
rki0ii nnEbEae EE i0 ˆ).̂(.. ��
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Stokes Vector and Mueller Matrices
2l
2r
22
2v
2h
2v
2h
EE
EE
EE
EE
V
U
Q
I
if V
U
Q
I
M
V
U
Q
I
44434241
34333231
24232221
14131211
MMMM
MMMM
MMMM
MMMM
M
Stokes vector completely describes intensity and polarization state of light.
Mueller matrix is a transformation matrix that is a property of material object
Check out examples of both
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Significance of Muller matrix elements in absorption and
scattering
See notes for more description
1'
1'
'1
'1
LBLBCD
LBCBLD
LBCBLD
CDLDLD
e AM
A B
B C
D
E
h f
j g
h j k
f g k
Absorption Scattering
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Measurement of Mueller matrix
• Do simple example – like detecting M14.
What kind of light do you put in?
• Use photoelasatic modulator taking advantage of modulation technique to
get good signal to noise.
)()(
)()(
Cos0Sin0
0100
Sin0Cos0
0001
= A Sin(wt)
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Apparatus
Light source 90o Polarizer
Sample
Filter?
detector
PEM at 45o
PEM Quartz (strain)
Apply ac voltage – piezoelectric crystal
Do examples
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Higher Order DNA Structure
www.library.csi.cuny.edu
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Nucleosome
www.answers.com
www.plyojump.com/courses/biology/week06.html
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30 nm fiber
Crystal Structure supports cross-linker model
(Nature 436, 138-141(7 July 2005)
http://cms.daegu.ac.kr/sgpark/molecular%20biology/VIBJI035.GIF
SolenoidCrosslinker
Nature Structural & Molecular Biology 12, 6 (2005)
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Protein Scaffold
http://www.molbio.unige.ch/laemmli/images/Fig1.jpg
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Function
Lampbrush chromosome
http://openlearn.open.ac.uk/file.php/2645/S377_1_041i.jpg
Polytene chromosomes from salivary gland cells of Drosophila larvae. Regions of condensed chromatin appear darkly stained whereas regions of de-condensed chromatin stain lightly.
www.bio.jhu.edu/~corces/Research2.html