1.
GasesAlojz Kodre,
Iztok Arčon,
Jana Padežnik Gomilšek, 2024, znanstveni sestavek v slovarju, enciklopediji, leksikonu
Opis: X-ray absorption spectroscopy of gases is seldom used for structural analysis,
except in as much as the extended X-ray absorption fine-structure (EXAFS)
signal is used to monitor some specific molecular process. Gas spectroscopy,
however, has been the main tool in the systematic study of higher-order
photoabsorption processes, multielectron photoexcitations (MEEs), which were
introduced with an experiment at the K edge of argon. Along with noble gases,
where MEEs are studied in the pure form, free of the structural signal,
measurements have been extended to monatomic metal vapours, although at the
cost of considerable experimental difficulties. Several types of absorption cells
have been devised, among them the ceramic double cell and the heat-pipe cell
for experiments in the low-energy region. In a high-temperature oven with
considerable technical refinement, edge profiles of nonvolatile metals were
measured up to 2500 K. Edge profiles and MEEs, which are strongly dependent
on electron correlation, provide sensitive tests of the theory of atomic and
molecular structure.
Ključne besede: X-ray absorption spectroscopy, absorption cells, gas and vapour samples, multielectron photoexcitation, effects of electron
correlation
Objavljeno v RUNG: 05.09.2024; Ogledov: 616; Prenosov: 4
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