Electronic structure measurements in CsI and xenon in the vicinity of the band gap at high pressure using non-linear optical spectroscopy
The near band edge structure of CsI has been examined at 9 K and at pressures up to 6 kbar using three-photon absorption spectroscopy. The pressure dependence of the three principal exciton-polariton states were measured. The energetically lowest of these, peak A, experienced a profound linewidth narrowing with increasing pressure. The author interpreted this effect in terms of the weak scattering limit of Toyozawa's model which proposes a relationship between the linewidth, exciton bandwidth, and the thermal fluctuation of lattice vibrations. The model predicts a rapid increase in the exciton bandwidth when our experimental results for the pressure dependence of the linewidth are used. The author measured the pressure dependence of the purely triplet paraexciton state. This level had a nearly linear energy increase on applied pressure up to 3 kbar, before turning over at 4 kbar. A rigorous observation of an n=3 level in the Wannier-Mott model relevant to the energetically lowest exciton-polariton was also made. From the n=2 and n=3 levels it was determined the band gap energy, exciton binding energy, exciton radius, and reduced exciton mass at 80 bars. Preliminary measurements were also made on solid Xenon at pressures between 3 and 9 kbar using the same technique. Initial measurements of the energetically lowest exciton-polariton level indicate an increase in the energy with applied pressure.
- Research Organization:
- Delaware Univ., Newark, DE (United States)
- OSTI ID:
- 7157014
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CESIUM IODIDES
ABSORPTION SPECTRA
ELECTRONIC STRUCTURE
XENON
BAND THEORY
EXCITONS
LINE NARROWING
NONLINEAR OPTICS
PRESSURE DEPENDENCE
ALKALI METAL COMPOUNDS
CESIUM COMPOUNDS
ELEMENTS
FLUIDS
GASES
HALIDES
HALOGEN COMPOUNDS
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
NONMETALS
OPTICS
PHOSPHORS
QUASI PARTICLES
RARE GASES
SPECTRA
664200* - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)