The nature of atoms at atomic pressures

At and beyond atomic pressures, E_H/a_B³_~30 TPa, where E_H is the Hartree energy and a_B is the Bohr radius, atoms are fundamentally changed by their environment. At such conditions, unbound electrons are squeezed interior to core orbitals of the atom, screening nuclear charge and dramatically shifting the electron energy levels. This presentation describes recent experiments, where Cr was compressed to billions of atmospheres pressure, while x-ray spectroscopy mapped the atomic shell structure versus pressure and temperature. These data quantitatively map the evolution of atomic orbitals as unbound electrons are compressed into the core orbits of atoms.