Anticrossing spectroscopy of K Rydberg atoms using 300-K blackbody radiation

The avoided crossings in an electric field of K s and p states with the nearly hydrogenic Stark manifold states have been investigated using 300-K blackbody radiation. Anticrossings between states of the same ‖$m_j$‖ for which the ‖$m_l$‖ values are the same or differ by one are encountered. The anticrossings between states of the same ‖$m_l$‖ are quite wide as they are due to core penetration and polarization effects. The anticrossings for which ‖$m_l$‖ differs by one are produced by the spin-orbit interaction and are accordingly quite small. We present results for the ns states for n in the range 18–29 and for the np states for n in the range 19–23.