Band-structure parameters and Fermi resonances of exciton-polaritons in CsI and CsBr under hydrostatic pressure

Abstract

Most alkali halides crystallize in the fcc sodium chloride structure. In contrast, with the exception of CsF, the Cs-halides form the simple cubic cesium chloride (CsCl) structure at ambient conditions and they have a substantially different electronic structure than other alkali halides; in particular, they have several nearly degenerate electronic levels near the Brillouin zone center. Highly resolved Three-Photon Spectroscopy (TPS) measurements allow direct observation of the near band edge structure and, in the case of CsI, probe more states than one-photon techniques. A number of interesting phenomena, among them level repulsion (Fermi resonance), occur as these levels are tuned through one another by application of hydrostatic pressure. To the best of our knowledge, this has been

Photoinduced Br Desorption from CsBr Thin Films Grown on Cu(100)

“…Theoretical models of Br-atom desorption from the α-CsBr (CsCl-type lattice) and β-CsBr (rocksalt-type lattice) surfaces induced by 6.4 and 7.9 eV ns laser pulses have been discussed in ref . The experimental band gap of β-CsBr is 7.3 eV, and the first singlet exciton peak occurs at 6.96 eV . The position of the surface exciton peak is not established experimentally, but our calculations predict it at ∼6.4 eV .…”

“…The experimental band gap of β-CsBr is 7.3 eV, 47 and the first singlet exciton peak occurs at 6.96 eV. 29 The position of the surface exciton peak is not established experimentally, but our calculations predict it at ∼6.4 eV. 30 This suggests that 6.4 eV photons can excite surface excitons but are unlikely to excite bulk excitons.…”

“…25 Laser activation is primarily associated with photophysics of the alkali halide thin film, although the Cu substrate plays a significant role in the overall process. The first exciton peak of bulk CsBr is 6.96 eV, 29 which is significantly higher than, for example, the 4.66 eV photon energy of the 266 nm YAG fourth harmonic output. Initial photoexcitation therefore proceeds through a two-photon process that deposits 9.32 eV of photon energy, leading to formation of electron hole pairs.…”

Electronic structure, Compton profiles and cohesive properties of Cs-halides

“…The poor agreement between the LCAO (HF and DFT) calculations and the experiment shows that these calculations Smith and Pong (1975) 7.90 7.30 6.50 (b) Nosenzo and Reguzzoni (1979) 8.01 7.15 5.98 (c) Lipp et al (2006) -7.20 6.14 (iii) Available theory (a) Satpathy (1986) 5.28 4.16 3.51 (b) Boer and Groot (1998) -4.10 -(c) Mei et al (2000) 5.10 5.20 4.20 LMTO: Linear muffin tin orbital method SCAD: Self consistent atomic deformation.…”

“…Recently, Mei et al (2000) vibration properties of alkali halides including CsX and compared their results with the other available data. Lipp et al (2006) have reported the band structure parameters of CsBr and CsI using three-photon excitation spectroscopy. Few other high-pressure phase transition studies on CsX compounds have also been reported by different workers (Nardelli et al, 1992;Schlosser and Ferrante, 1993;Tsujimoto et al, 1996).…”