We have measured the photoabsorption spectra of Pb II and Bi III in the wavelength range between 37 and 70 nm. A number of features in the spectra have been identified with the aid of the Cowan suite of atomic codes. 5d → 6p transitions from the ground configuration (5d106s26p) and three excited configurations (5d106s26d, 5d106s27s, 5d106s6p2) give rise to the most prominent features in the measured spectra. Evidence of excited states including (5d106s6p2 (4P3/2, 4D3/2)) for Pb II and (5d106s6p2 (4P1/2, 4P3/2)) for Bi III was observed in our measurements.

Results of angle-resolved electron spectroscopy of near-threshold photoionization of Ne atoms by combined femtosecond extreme ultraviolet and near infrared fields are presented. The dressedelectron spectra show an energetic distribution into so-called sidebands, being separated by the photon energy of the dressing laser. Surprisingly, for the low kinetic energy (few eV) sidebands, the photoelectron energy varies as a function of the emission angle. Such behavior has not yet been observed in sideband creation and has not been predicted in commonly used theoretical descriptions such as strong field approximation and soft photon approach. Describing the photoionization with a time-dependent Schrödinger equation allows a qualitative description of the observed effect, as well as the prediction of fine structure in the sideband distribution.

Steel impacts a variety of industries such as construction, automotive and ship building. The physical properties of steel (e.g., hardness, weldability) are significantly affected by the concentration of carbon. Hence,...

In this work we report soft x-ray (SXR) photoabsorption measurements in neutral methane and carbon dioxide molecules and their corresponding photoionized plasmas. The SXR radiation was generated by a table-top laser produced plasma source based on a double stream gas puff target. At low SXR intensities only features related to neutral molecules are present in the absorption spectrum. On the other hand, as the radiation intensity increases, we observe new absorption features in the low photon energy side of the spectrum. In that case fragments such as neutral and ionized molecules, atoms and atomic ions are found to contribute to the absorption spectrum of the plasmas. To our knowledge these are the first measurements where this laser plasma based SXR source is used to both create and probe a molecular plasma. Emphasis is placed on identifying the fragment species and the corresponding transitions.

We report angle-resolved measurements on photoelectrons emitted upon near-threshold two-photon double ionization (TPDI) of Kr irradiated by free-electron laser (FEL) pulses. These photoelectron angular distributions (PADs) are compared with the results of semirelativistic R-matrix calculations. As reported by Augustin et al.[Phys. Rev. A 98, 033408 (2018)], it is found that the presence of autoionizing resonances within the bandwidth of the exciting FEL pulse strongly influences the PADs. In contrast to measurements on lower-Z targets such as Ne and Ar, the larger spin-orbit interaction, inherent in 4p-subshell hole states of Kr, permits us to resolve and study PADs associated with some of the fine-structure components of the Kr + and Kr 2+ ions.