A partial list would include the Patterson
function, isomorphous replacement, and anomalous scattering, which enabled the determination of organic structures; direct (i.e., purely computational) methods of phase determination, which enabled small - molecule crystallography to be almost totally automated; synchrotron radiation and area detectors, which together made it possible to collect data on macromolecular structures in hours instead of months; and automatic interpretation of
electron density maps.
what exactly is it that determines the probability of an energy transition such as an
electron emitting or absorbing a photon (besides
densities and occupancies of states and incident photons, etc.)-- and how does refractive index affect this (it has to because the Planck
function is proportional to n ^ 2 — has to be in order to satisfy 2nd law of thermo...)-- and does it make sense to use an k, E diagram when
electrons are not actually propagating as plane waves — I mean, what is the wavevector when the waveform is not a plane wave; is k a
function of space in atomic orbitals?