Soft X-ray absorption spectroscopy of Ar₂ and ArNe dimers and small Ar clusters

Abstract

The X-ray absorption spectra (XAS) of Ar2 and ArNe dimers and small Ar clusters in the L2,3 region (244-252 eV) of the Ar atom have been recorded using synchrotron light and a combination of coincidence methods and kinetic energy discrimination of energetic ions. The absorption peaks in the spectra of the dimers and clusters were found to be shifted and broadened relative to the peaks in the spectrum of the Ar atom. In order to unambiguously relate these chemical shifts to the electronic structure of the core excited states in dimers, we performed ab initio calculations of the XAS spectra. Implications of the results for the use of XAS as a structure determination method in large rare gas clusters are discussed.

Real-time observation of the Woodward–Hoffmann rule for 1,3-cyclohexadiene by femtosecond soft X-ray transient absorption

“…The spectrometer was calibrated using the L 2,3 absorption lines of argon atoms around 250 eV. 39,40 The cross-correlation between the pump and probe pulses was determined from the AC Stark shift of the 2p 3/2 -3d absorption line of argon atoms. The spectrogram of the AC Stark shift and temporal evolution of DA is shown in Fig.…”

X-Ray absorption spectra of microsolvated metal cations

“…In smaller clusters this effect becomes apparent as line shifts in X-ray absorption spectra which are shifted to the blue for the lowest Rydberg states and to the red for the higher ones. 16,17 In larger rare gas clusters or solids the environment not only perturbs the core excited states, but also facilitates the delocalisation of an electron promoted to higher Rydberg orbitals 18,19 throughout the cluster or the solid. This process is called ''internal ionisation'' to distinguish it from the vacuum ionisation concept in which the electron is free to leave the cluster altogether.…”