9. Interaction of light with molecules Flashcards
What is Rayleigh scattering dependant on?
wavelength
How is the size of the particle compared to the wavelength for Rayleigh scattering?
particle is much smaller than the wavelength
What type of collision happens in Rayleigh and Mie scattering?
elastic collisions
What is the size of the particles compared to the wavelength for Mie scattering?
size of particle > wavelength/10 : comparable size
What determines the colour of the clouds?
size of water droplets : the bigger the darker the cloud
What is turbidimetry?
the process of measuring the loss of intensity of transmitted light. Measures absorbance
What is turbidimetry?
measures the intensity of scattered light
What can be determined by using dynamic light scattering (DLS)?
size distribution of small particles in suspension
What does DLS measure?
the brownian motion (random movement of particles due to collisions) to calculate the diffusion constant and then the size
What can be used to determine the diffusion constant?
temporal intensity fluctuation graph
What is the height of the absorption maxima proportional to?
it is proportional to the concentration
In case of molecules, what does the energy level depend on?
vibrational bond distance
