Angle-resolved energy dependence of the4p4nd(2S1/

Abstract

We measured and calculated the energy dependence of the 4p 4 nd( 2 S 1/2 ) (nϭ4 -7) correlation satellites in Kr from 38.5 to 250 eV. Our high-resolution measurements used a photoelectron spectroscopy technique to determine the relative cross sections and angular distribution parameters ␤. We find that, as in the case of Xe, the absolute cross sections of these satellites lines follow very closely the shifted and scaled cross section of the 4s main line. However, in the case of ␤, we find that the nd( 2 S 1/2 ) (nϭ4,5,6) follow the ␤ value of the 4s main line below 150 eV only, and that ␤ of the 7d( 2 S 1/2 ) satellite does not. We find that the ␤ of the nd( 2 S 1/2 ) ͑nϭ4, 5, and 6͒ satellites reach ␤ϭ2 below 150 eV, but this value drops significantly between photon energies of 200 and 250 eV. While the comparison of our measurements with our calculation is good overall, some effects are not reproduced by the calculation. Our results are compared with a previous measurement at 68.5 eV, and the agreement is fair. We also measured the 4s and 4p main line cross sections and angular distributions and these results are compared to previous measurements and calculations.

Isolated high-harmonic XUV photon absorption and NIR strong-field tunnel ionization

“…Comparing the σ 4s and σ 4s satellite photoexcitation cross-sections to the 4s −1 and 4p −1 main-line photoionization cross-sections, it appears that the 4p satellite follows the energy dependence of the 4p −1 main line, which is most likely the result of DSU and CI dominating, as this route is 20 eV above threshold. This confirms the observations [4,7] at a significantly lower photon energy despite using a radically different experimental configuration. The 4s satellite exhibits a distinct divergence from the 4s −1 crosssection although a minimum is predicted.…”

“…The satellite states populated during photoionization of Kr by synchrotron radiation have been studied extensively with high-resolution photoelectron spectroscopy [3][4][5][6][7][8]. There is a general agreement on state assignment, however the mechanisms leading to the population of these states are disputed, especially in the vicinity of photoionization thresholds [4,[6][7][8].…”

“…The satellite states populated during photoionization of Kr by synchrotron radiation have been studied extensively with high-resolution photoelectron spectroscopy [3][4][5][6][7][8]. There is a general agreement on state assignment, however the mechanisms leading to the population of these states are disputed, especially in the vicinity of photoionization thresholds [4,[6][7][8]. A number of experimental studies have observed that some satellite lines follow the photon energy dependence of the 4s −1 main line [4,7,8,25,26] and [4] also observed that a second group of satellite lines follow 4p −1 .…”

“…Over the H21, H23, H25 and H27 photon range (32.8-42.1 eV), krypton is either 4p −1 or 4s −1 photoionized as illustrated in figure 2(b), with the photoionzation partial cross-sections shown in figure 2(c). During photoionization, bound 4p electrons have a small probability of being excited into unoccupied orbitals [3,4,6,7] populating satellite states, as discussed below. Following single photon ionization and the population of a range of satellite states, the NIR strong-field pulse then initiates tunnel ionization of the excited electrons and the TOFMS records the final charge of ions extracted from the focal volume.…”

“…In this work, we undertake a novel investigation of atomic ionization dynamics using monochromated high harmonic extreme ultraviolet (XUV) radiation and ultrafast strong-field near-infrared (NIR) pulses. Krypton is 4s −1 or 4p −1 photoionized, populating satellite states via the electron correlation [3][4][5][6][7][8]. Subsequent tunnel ionization [9, 10] of the satellites allows the relative photoexcitation populations and relative cross-sections to be recovered in a pump-probe configuration.…”