Anisotropy parameters describing the angular dependence of the photoionization delay are defined. The formalism is applied to results obtained with the relativistic random phase approximation with exchange for photoionization delay from the outermost s-orbitals in selected rare-gas atoms. Any angular dependence in the Wigner delay is induced here by relativistic effects, while the measurable atomic delay exhibits such a dependence also in the nonrelativistic limit. The contributions to the anisotropy from the different sources are disentangled and discussed. For the heavier rare gases, it is shown that measurements of the delay for electrons ejected in specific angles, relative to, e.g., those ejected along the laser polarization, are directly related here to the Wigner delay. For a considerable range of angles, the contributions from the second photon largely get canceled when the results in different angles are compared, and this angle-relative atomic delay is then close to the corresponding Wigner delay.

Time delay in photodetachment has been investigated for few negative ions, Cl-, Br-, I-, and Li-. Very few studies on photodetachment time delay for negative ions are present till date and have been reviewed briefly in the present article. Different many body formalisms, like RRPA, RRPA-R and RMCTD, have been employed to obtain new results on photodetachment time delay, accounting for important electron correlations present in the negative ions studied here. Results on time delay show significant angle dependence near the threshold region, at shape resonance and at Cooper minimum region.

Photoionization cross sections and delays are calculated within the relativistic random phase approximation with exchange for xenon and radon in the energy region between the first and second ionization threshold. Resonance parameters for the first few resonances in both systems are presented and the angular dependence is discussed.