Hard x-ray photoelectron spectroscopy on heavy atoms and heavy-element containing molecules using synchrotron radiation up to 35 keV at SPring-8 undulator beamlines

Abstract

We have recently initiated hard x-ray photoelectron spectroscopy experiments on heavy atoms and heavy-element containing molecules in gas phase by using synchrotron radiation up to 35 keV at SPring-8 undulator beamlines. We have successfully measured deep inner-shell photoelectron spectra, as well as L-MM and M-NN Auger electron spectra excited below and above the K-edge of heavy elements. Target specimens utilized for the preliminary experiments are Ar, Kr and Xe atoms, and also iodine in iodomethane (CH 3 I) and trifluoroiodomethane (CF 3 I) molecules, respectively. We show some selected results on the extracted core-hole lifetime broadenings for the iodine 1s core level of the CH 3 I molecule and also for the Xe 2s, 2p core levels, to compare with theoretical values. The L-MM Auger electron spectra of Kr recorded at 13 and 16.6 keV excitation energies are also shown as typical examples, and the spectrum measured above the K-edge, i.e. 14.327 keV, is analyzed based on theoretical calculations using the Hartree-Fock method. As a result, we give a tentative assignment for the double-core-hole hyper-satellite LL-LMM Auger transitions of the Kr atom.

Deep core photoionization of iodine in CH3I and CF3I molecules: how deep down does the chemical shift reach?

“…The shapes of the iodine 1s spectra of CH 3 I and CF 3 I are similar to the 1s spectrum of atomic Xe. 5,6 The main line is accompanied by a satellite shoulder and a very broad tail that extends about 140 eV above the main line. Such similarity is expected since the iodine 1s ionized state of CH 3 I and CF 3 I is not dissociative and the large lifetime broadening smears out vibrational and rotational effects.…”

“…To complement the information from photoelectron spectra, Auger LMX spectra have also been measured. As in the previous work on Kr 5 and Xe, 6 the comparison of the LMX decay above and below the K-edge is informative about the importance of radiative versus nonradiative decay.…”

“…A novel major development in this direction has taken place at the synchrotron radiation facility SPring-8 in Japan, where two hard X-ray beam lines equipped with end stations capable of measuring gas-phase samples have recently come into operation. 5 Exploiting this new instrumental opportunity, a pioneering paper by us on the 1s ionization of xenon (ionization energy B35 keV) has not only shown the feasibility of this kind of experiment, but has also shed light on the novel information that can be extracted. In particular, a core-hole lifetime in the attosecond range was derived, together with direct evidence of the relative weight of radiative (photon emission) versus nonradiative (Auger) decay following K-edge ionization of Xe.…”

Hard x-ray spectroscopy and dynamics of isolated atoms and molecules: a review

“…At SPring-8, Japan, hard x-rays up to 40 keV are available. Recently some experiments on isolated atoms and molecules have been performed by M. Oura and the local team in collaboration with some of us on two RIKEN beam lines [76]. Xe 1s photoionization and decay [77] and I 1s photoionization and decay in CH 3 I and CF 3 I [78] were recently measured there.…”

Electron spectroscopy and dynamics of HBr around the Br 1s−1 threshold

“…Availability and opportunity of combining a high-photonenergy source with a high-resolution hemispherical energy analyzer, such as the hard X-ray photoelectron spectroscopy (HAXPES) end station at GALAXIES beamline, 1,2 SOLEIL synchrotron, has opened new avenues for the investigation of photoionization and photoexcitation dynamics. 3,4 A similar spectroscopic set-up has been developed also recently at SPring-8 in Japan by Oura et al 5 These new possibilities allow, for example, studying nuclear dynamics on the sub-femtosecond time scale for K-shell ionization and relaxation of heavy element containing molecules via normal Auger, absorptionlike and resonant Auger (RAS) spectroscopies. In the present work we concentrate on the Br K-edge (D13.48 keV) in the HBr molecule.…”