Ultraviolet photoemission studies of BaF2and BaCl2

Abstract

Photoemission measurements on evaporated films of BaF2 and BaC12 were made at photon energies of 8-27 eV. Spectral quantum yields and energy distributions of photoemitted electrons were measured. The photoelectron spectra show high-density-of-states structures at 2.5+0.2, 5.2+0.2, and 7.5+0.2 eV above the vacuum level for BaF, and 3.5+0.2 eV above the vacuum level for BaC1,. The spectra also provide information on the valence-band widths, band thresholds, and the spin-orbit splitting of the Ba++ 5p core band of BaC12. The energy differences between the regions of initial and final high densities of states are compared with the transition energies of certain structures found in the optical and energy-loss spectra of BaF,.

Particle size effects on structural and optical properties of BaF2 nanoparticles

“…It should be pointed out that the large differences in the diffusion coefficients of Ba and F ions (approximately two orders of magnitude) lead to Ba ions diffusing slower than F ions during the BaF 2 nanoparticles' growth. 49 This can lead to a more easy and rapid increase in the F-F bond length than that of the Ba-F bond, 50 resulting in a high density of uorine vacancies in the (111) surface of the BaF 2 nanoparticles. 51 As a result, this can lead to a notable surface-induced tensile strain, discussed elsewhere.…”

Calculation of the Band Gap Energy and Study of Cross Luminescence in Alkaline-Earth Dihalide Crystals

“…We can, however, obtain a reasonable description of a delocalized conduction state by relaxing some of the orthogonality requirements imposed by the TES (see below). The electronic affinity χ is always a small quantity, close to zero for all these ionic materials, [46][47][48][49] and our description gives values of the correct order of magnitude (a few tenths of eV). As typical errors in measured gaps are ∼ 0.5 eV, the quantitative determination of the band gap energy is not critically affected by our approximations.…”

Electronic properties of fluorides by efficient approximated quasiparticle DFT-1/2 and PSIC methods: BaF2, CaF2and CdF2as test cases

“…Projected DOS are shown with different colors and the VBM defines the energy zero. The experimental positions of the orbitals Ba(5p) (−7.3 eV[56]), Ca(3p) (−15.6 eV[2]) and Cd(4d) (average value between −5.35[57] and −6.0 eV[5]) are shown by a vertical red dashed lines. Notice that no peak of semicore Ca p states is present for the PSIC since they were not included in the pseudopotential non-local projectors.…”