Measurement of the Electron Affinity of Cerium

Abstract

The electron affinity of cerium has been measured using laser photodetachment electron spectroscopy. The electron affinity of Ce(1G4) was determined to be 0.955 +/- 0.026 eV. The data also show that Ce- has at least two bound excited states with binding energies of 0.921 +/- 0.025 eV and 0.819 +/- 0.027 eV relative to the (1G4) ground state of the cerium atom. The present experimental measurements are compared to recent calculations of the energy levels of Ce-. Strong disagreement with the most recent theoretical atomic structure calculations highlights the complicated nature of this particular lanthanide.

Experimental and theoretical study of bound and quasibound states ofCe−

“…The present result is also in good agreement with recent calculations by Felfli et al of 0.61 eV [15] and by Cao and Dolg of 0.58(10) eV [5]. Although the LPES experiment by Davis and Thompson yielded a much higher electron affinity of 0.955(26) eV [16], the subsequent reinterpretation of the LPES data by O'Malley and Beck determined an electron affinity of 0.660 eV [14], which is consistent with the present result.…”

“…Recent theoretical calculations of the electron affinity of Ce, corresponding to the binding energy of the ground state of Ce − , range from 0.511 eV [14] to 0.61 eV [15]. Experimentally, laser photodetachment electron spectroscopy (LPES) of Ce − was used by Davis and Thompson to determine a value for the electron affinity of 0.955 (26) eV [16]. However, a subsequent reinterpretation of the LPES data based on comparisons to theoretical calculations of photodetachment cross sections yielded an electron affinity of 0.660 eV [14], which is substantially lower than the original LPES value [16] but is consistent with previous ab initio theoretical values [5,13,15].…”

Autodetachment lifetime calculations of long-lived metastable states of Ba−and Eu−

“…Tm − [1], Ce − [2], and Eu − [3]. In some cases these values are ∼0.5 to ∼0.9 eV higher than earlier calculated electron affinities [4,5].…”

“…While it is unlikely that a single explanation may be found to resolve the differences between experiment and theory in all these cases, our efforts have been directed toward studies of long lived excited states, most recently in Tm − [6]. The supposition is that the experiments [1,2,3] may be measuring the difference between a metastable state of the negative ion and an excited threshold of the neutral atom rather than the true electron affinity (EA).…”

Cerium Oxide Nanoparticles Improve Outcome afterIn VitroandIn VivoMild Traumatic Brain Injury

“…The crystal lattice structure of the oxide form affords even more redox capacity because of electron ''holes'' or oxygen defects in the nanoparticle matrix. 16 Creation and annihilation of oxygen vacancies and alterations in cerium valence impart exceptional redox activity to cerium oxide nanoparticles (CeONPs), which is further enhanced by the increased surface area and quantum lattice alterations that occur at the nanoscale. 17,18 In contrast to traditional antioxidants, the radical scavenging activity of CeONPs is regenerative under biological conditions, [19][20][21] permitting sustained activity.…”