Rate of field ionization from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>S</mml:mi></mml:math>states with a quantum defect

Abstract

The WKB approximation in parabolic coordinates is used to calculate electric-field-ionization rates from $L=0$ states with quantum defects. The range of applied electric field and principal quantum number have been given for which the rate formula is valid. Previous studies of field ionization of shallow impurity levels with quantum defects in solid-state systems have shown this formula to be in agreement with experiments.