Quantum Raman (5) Flashcards
For Rayleigh scattering, what is the energy of incident monochromatic radiation?
hv0
Upon Rayleigh scattering, what is the energy of the elastically scattered radiation?
hv0
What is the change in the system for rayleigh scattering?
no change in energy
What is the change in the system for raman scattering?
Change in energy = hv0
Does a molecule gain or lose energy during Stokes Raman scattering?
gain
From what initial energy level does stokes raman scattering occur?
ground
In what final energy level does the molecule tend for stokes raman?
excited
From where does the energy for the transition in Stokes Raman come?
annihilation of photon energy and simultaneous creation of photon with lower energy
What is the energy of the photon after the Stokes inelastic collision?
Lower
What is the energy of the molecule after the Stokes inelastic collision?
Higher
Does a molecule gain or lose energy in Anti-stokes raman scattering?
lose
from what initial energy level does anti-stokes raman scattering occur>
lower
in what final energy level does the molecule end for anti?
higher
From where does the energy for the anti-stokes raman scattering come>
inelastic collision energy transfers to incident photons
What is the energy of the photon after the anti stokes inelastic collision?
hv0
What is the energy of the molecule after the anti-stokes inelastic collision?
h(ṽ0 + ṽv)
What are some of the common excitation wavelengths used in raman spectroscopy and their corresponding energies?
Argon (λ 488) E = 20,492
Argon (λ 514.5) E = 19,436
Krypton (λ 647.1) E = 15,453
He-Ne (λ 632.8) E = 15,802
Why are raman spectra characterized by wavenumber shifts rather than absolute wavenumber?
ensures bands always plotted the same independent of particular laser excitation energy used in experiment
How are wavenumber shifts calculated?
Δṽ’v = ṽ0 - ṽ’
In what energy level do most molecules exist at room temperature?
ground
How does the energy level at RT affect the intensity of the stokes vs anti-stokes bands?
stokes is much more intense
How does the intensity distribution of anti-stokes raman bands change with increasing wavenumber away from the exciting line>
increases with increasing wavenumber
Stokes vs Anti-stokes
stokes is in the ground state, anti-stokes starts in an excited state
