We discuss the creation of pairs of charged particles in an alternating electric field. The dependence on the frequency is computed and found negligible. We obtain a formula for the field intensities required in order to observe the effect $E\gtrsim \frac{m{\omega }_{0}c}{esinh\left(\frac{\hslash {\omega }_0}{4m{c}^2}\right)}$.

• Received 15 April 1970

DOI:https://doi.org/10.1103/PhysRevD.2.1191