Time delay in two-electron photodetachment and tests of fundamental threshold laws

The photoelectron group delay, also known as the Wigner time delay (WTD), is examined in photodetachment of the and ions near their lowest inelastic and the double detachment thresholds. These threshold processes promoting the remaining bound electron to an excited state or ejecting it to the continuum involve two active electrons and are termed collectively two-electron photodetachment. The opening of an inelastic channel is governed by the Wigner threshold law which affects the WTD very differently in and . At the same time, the Wannier threshold behavior of the WTD in double detachment is similar in both targets. Experimental verification of these theoretical predictions will subject the Wigner and Wannier threshold laws to a set of stringent tests in the time domain.