Recent experimental and theoretical developments in time-resolved X-ray spectroscopies

Higher-order time-symmetry-breaking phase transition due to meeting of an exceptional point and a Fano resonance

“…The drastic change in the higher order TSBPT due to the cooperation of the EP and the Fano resonance at the continuum threshold shown in Fig.5 can be experimentally observed in the autoionization decay of an atom or a molecule with use of time-resolved ultrafast spectroscopy [52][53][54][55]. Here we propose an experiment which uses a combination of time-resolved x-ray absorption (TRXAS) [56] and time-resolved photoelectron spectroscopies (TR-PES) [57], as shown in Fig.9, which should capture this characteristic phase transition. In TRXAS, an ultrashort x-ray pulse excites a core electron to the discrete states near the ionized threshold, such as Rydberg states, and Rabi oscillation is induced between the resonance states by the pulsed excitation, which is observed by a delayed absorption probe.…”

Photoaquation Mechanism of Hexacyanoferrate(II) Ions: Ultrafast 2D UV and Transient Visible and IR Spectroscopies

“…Molecular dynamics simulations will be needed to further support this scenario. In addition, ultrafast x-ray spectroscopy provides ideal tools to detect both the nuclear, electronic and spin structure of the intermediate pentacoordinated form 86 and studies are on-going at x-ray free electron lasers to this purpose. 3-a An additional <1 ps contribution is observed, which can be attributed to overlap with the CN -band (see Figures 7 and S8).…”

The Study of Reactive Intermediates in Condensed Phases

“…96,97 These short wavelengths excite core electrons to valence orbitals or the ionization continuum, and are element specific and sensitive to the oxidation state and local chemical environment of the probed atoms. Measurements to date have mostly used synchrotron light sources, with time resolution reaching the picosecond range, although adapted synchrotrons and X-ray free electron lasers (XFELs) access picosecond and femtosecond timescales.…”

“…Examples in the literature mostly focus on evolving electronic structure, changes in spin state and structural changes in coordination complexes of transition metals (TMs) and metalloproteins. 97 Access to synchrotron or XFEL beam time has so far limited the application of these X-ray based methods, but table-top laser sources of extreme ultraviolet (XUV) and X-ray radiation are becoming available for laboratory (rather than national facility) based studies, 96 and should lead to further exploitation of these powerful techniques. For example, Leone and coworkers recently showed that XUV pulses produced by high harmonic generation of 35-fs pulses from a titanium:sapphire laser could probe core-to-valence transitions in iodine atoms during the 266-nm induced dissociation of the C-I bond in methyl iodide.…”