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X-ray-excited Auger and Photoelectron Spectroscopy
Published in M. Prutton, Electronic Properties of Surfaces, 2018
In the Auger process an electron is ejected from an atom by the radiationless decay of an initial state with a single core hole, [nala], into a less bound final state with two core holes [nblb, nclc]. Specific Auger transitions are usually denoted by the x-ray notation for the three levels involved, i.e. KL1L1 for a [1s] to [2s2] transition. Historically Auger spectra have been a powerful tool for assessing developments in atomic structure calculations, the calculation of Auger transition rates in particular being a very sensitive test of the wavefunctions employed. Until quite recently most attention was centred on the simplest Auger spectra, the KLL transitions, and the extensive work on these transitions has been regularly reviewed (Burhop 1952, Mehlhorn 1969, 1978, Bambynek et al 1972, Sevier 1972, Burhop and Asaad 1972, Geiger 1973, Chattarji 1976).
Conversion of Hydrilla verticillata to bio-oil and charcoal using a continuous pyrolysis reactor
Published in Biofuels, 2021
Kittiphop Promdee, Doungkamon Phihusut, Apisake Monthienvichienchai, Yaowapar Tongaram, Pattarapol Khongsuk
In order to confirm the elemental composition of the Hydrilla charcoal, dispersive X-ray spectroscopy (EDS) was utilized, as shown in Figure 8. The charcoal was found to contain 18.94 wt% C and 1.52 wt% O, with no other impurities (N, Mg, K, Fe, Al, Ca, Si, F or Cl). The elemental composition was obtained with k-electron shell, which suggested that a principal energy level may be considered an orbit followed by electrons around an atom's nucleus. The k-shell corresponds with the principal quantum numbers (n = 1, 2, 3, 4,…) or is labeled alphabetically with letters used in X-ray notation (K, L, M,…). The atomic percentage showed C (92.64%), O (5.58%) and Ca (0.64%) and other trace atomic elements, such as N, Si, Cl, F, Fe, K, Cl, Mg and Al. This indicates that a high-purity charcoal structure was formed. Additionally, a high surface area and high micropore rate may endow the Hydrilla charcoal with properties suitable for broad utilization as an active material with fast ion diffusion at a high porosity during the pyrolysis process [49–52]. Thus, given this property, the Hydrilla charcoal could be used to improve the design of pyrolysis operation in future research.