Abstract

The threshold behavior of laser photodetachment cross sections of negative ions is usually described by the law discovered by Wigner four decades ago¹:σ →k^(2l+1), where ħk and ħl are the linear and angular momenta of the outgoing electron. The Wigner law is a threshold law: it holds near threshold. There is little theoretical guidance about how close to threshold one has to be. The law is said to hold if the deviation between the law and reality is less than some arbitrary fraction. That is, there has been little theoretical guidance about either the range of validity or the accuracy of the Wigner law.

© 1990 Optical Society of America