Bright lights, small systems: Molecular differentiation using free-electron lasers
(PhysOrg.com) -- Double-core-hole (DCH) states in which two electrons are ejected from their positions, creating vacancies occurring at different atomic sites are very sensitive to the chemical environment of the two holes. While differentiating between similar chemical systems using double-core-hole spectroscopy has historically been examined only theoretically, and so far there is no published work on two-site DCH states using conventional X-ray photoelectron spectroscopy based on single-photon ionization. However, a study led by Western Michigan University researchers has recently reported direct observation of double-core holes with single vacancies on two different sites produced using short, intense X-ray pulses from the Linac Coherent Light Source (LCLS) free-electron laser (FEL). Their results compare favorably with theoretical modeling, which the scientists say proves the feasibility of their approach.
