Relativistic effects in photoionization time delay near the Cooper minimum of noble-gas atoms

Abstract

Time delay of photoemission from valence ns, np 3/2 , and np 1/2 subshells of noble-gas atoms is theoretically scrutinized within the framework of the dipole relativistic random phase approximation. The focus is on the variation of time delay in the vicinity of the Cooper minima in photoionization of the outer subshells of neon, argon, krypton, and xenon, where the corresponding dipole matrix element changes its sign while passing through a node. It is revealed that the presence of the Cooper minimum in one photoionization channel has a strong effect on time delay in other channels. This is shown to be due to interchannel coupling.

Relativistic calculations of angle-dependent photoemission time delay

“…In addition, where available, experimental threshold energies from [16] were used to facilitate better comparison with experiment. These energies are identical to those displayed in Table 1 of [8].…”

Attosecond time delay in the photoionization of Mn in the region of the3p→3dgiant resonance

“…A series of experiments was conducted recently using attosecond pulse trains (ATP) [2][3][4][5][6]. Thus produced experimental results were analyzed using several theoretical models of various degrees of sophistication [7][8][9][10][11][12][13][14][15]. At the same time, there exists a large body of literature on photoemission time delay in condensed matter but reviewing this literature is outside the framework of the present article.…”

Attosecond chronoscopy of photoemission

“…These can have either positive or negative sign, depending on whether the phase jump is positive (+ ) or negative (− ). Photoionization of the Ar 3 electron with one radial node features a Cooper minimum at a photon energy XUV ≈ 45 eV already at the Hartree-Fock-level (Amusia, 1990;Starace, 2006) while strong 3 -3 intershell correlations are responsible for a deep Cooper minimum in the Ar 3 photoionization cross section near 42 eV (Dahlström et al, 2012a;Kheifets, 2013;Carette et al, 2013;Dixit et al, 2013;Dahlström and Lindroth, 2014;Saha et al, 2014). These photon energies are within reach of attosecond XUV pulses and have been investigated by combining an attosecond pulse train with an IR field.…”

“…The situation is strikingly different for many-electron atoms. First experiments were performed for rare gas atoms (Schultze et al, 2010;Klünder et al, 2011;Guénot et al, 2012), the results of which have led to a flurry of theoretical investigations (Schultze et al, 2010;Kheifets and Ivanov, 2010;Komninos et al, 2011;Nagele et al, 2011Nagele et al, , 2012Nagele et al, , 2014Baggesen and Madsen, 2011;Zhang and Thumm, 2010;Ivanov and Smirnova, 2011;Dahlström et al, 2012bDahlström et al, , 2013Dahlström et al, , 2012aPazourek et al, 2012a,b;Śpiewanowski and Madsen, 2012;Pazourek et al, 2013;Moore et al, 2011;Carette et al, 2013;Kheifets, 2013;Dixit et al, 2013;Feist et al, 2014;Saha et al, 2014;Wätzel et al, 2015). Yet, satisfactory agreement between theory and experiment is still outstanding and many open questions remain.…”