Light

1
Light Spectra

• Continuous Spectra
• Blackbody spectrum
• Emission Spectra
• unique to each element
• Absorption Spectra
• unique to each element
• reverse of emission spectra
• Kirchhoff's Laws
• solid/liquid/dense gas gt continous
• hot low density gas gt emission
• cool low density gas gt absorption

2
Formation of Spectral Lines

• Atomic Structure
• nucleus electrons
• Bohr model
• orbitals energized states
• ground state
• ionized state
• excited state
• electron cloud
• energy electron radius
• light as a particle
• photons
• energy frequency

3

• Hydrogen Spectrum
• Ground state gt UV
• 1st excited state gt Visible
• Balmer series
• Kirchoffs laws revisited
• Complex spectra
• Helium iron
• Molecules
• Chemical bonds gt spectral lines
• Spectral line analysis
• Composition
• Temperature
• Line of sight velocity
• Rotation rate
• Pressure
• Magnetic field
• Zeeman effect

4
Doppler Effect

• Relative motion produces a shift in wavelength!!!
• Transverse motion vs. radial motion
• Measures
• motions of stars
• Distant galaxies
• Expansion of universe