PHY 102 Lecture Notes - Lecture 19: Photon Energy, Stimulated Emission, Photon
Document Summary
Band of energy levels = electrons exist, can transition. Band gap is very large: electrons cannot pass this gap and thus, cannot be excited to the conduction band. Electrons sit on valence band (band of energies where electrons are permitted to move) Semiconductor may or may not conduct electricity. Band gap between valence band and conduction band is small. Photon energy = ephoton = efinal einitial = hf = hc/ . Energy levels of electrons bound to atoms = discrete, unique to each atom. Absorption = atom absorbs energy of photon: promotes to higher energy orbital. Emission = atom emits energy of photon: electron falls from higher energy to lower energy orbital. Laser beams are: coherent, intense, single frequency, narrow. Wide applications in science, tech, biomedical applications. Electron moving from high-low energy is spontaneous. Incoherent radiation from excited atoms: de-excitation occurs with different photons, with different wavelength.
