Light Scattering Problem Set

1 (A)
Calculate the Raleigh Ratio (Rsubtheta) for the following system
Molecular weight: 4,000,000 g/mole
index of refraction: 1.33 (unitless)
the specific refractive index increment (i.e., change in index of refraction with concentration): 0.198 1/M
wavelength of light: 280 nm (not polarized)
concentration: 1.5 mg/ml

1 (B)
What is the Raleigh Ratio at 500 nm?

1 (C)
At at an angle of 90 degrees, wavlelength of 280 nm, and a distance of 10 cm, calculate the intensity of the light scattered (i.e., i/Io) by this protein.

1 (D)
For those same conditions, graph i/Io as a function of the scattering angle theta ( 0 < theta < 90).
(this excel spreadsheet might be useful)

2 What is the ratio of Rayleigh scattering of red light (700) to scattering of blue light (400 nm).

3) If molecular assembly A (an assembly is a large complex like a nucleosome or a ribosome) has twice the frictional coeffient of molecular assembly B
A) What is the ratio the two diffusional coefficients?
B) What happens to the ratio of the diffusional coeffients when the temperature is doubled?
B) What is the ratio of their radii (assuming both are spheres)?
C) What could you learn about these assemblies by small angle x-ray scattering?
D) what could you learn about these assemblies by small angle neutron scatterning?
E) what could you learn about these assemblies by analytical ultracentrifugation?