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Title: Electromodulation spectroscopy of sc and fcc phase TlCl and TlBr

Technical Report ·
DOI:https://doi.org/10.2172/7345612· OSTI ID:7345612

Electromodulation measurements were made on these compounds and the spectra were reduced to the electric field induced changes in the dielectric function. The results indicate the importance of photocarrier effects in both theory and experiment in the electromodulation of exciton states. In the future, calculations should include the effect of photocarriers on the field seen by the exciton and experimentally samples should be developed with known and reproducible photocarrier properties with temperature control between liquid helium and nitrogen temperatures and bipolar modulation fields. The abnormal (fcc) phase electroabsorption (EA) measurements have demonstrated the usefulness of the modulation method in resolving exciton states by determining the n = 2 energy in TlBr. This has enabled a number of quantities to be calculated from the Wannier exciton model. The resolution of the n = 2 energy in TlCl is probably also possible with an EA measurement and patience with the signal to noise problem. The ..cap alpha.. and ..beta.. features are still unassigned but the unusual EA lineshape and sample preparation sensitivity found in this investigation may prove useful in making definitive assignments in conjunction with future work.

Research Organization:
Ames Lab., Ames, IA (United States)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
7345612
Report Number(s):
IS-T-721
Resource Relation:
Other Information: Thesis. Submitted to Iowa State Univ. of Science and Technology, Ames
Country of Publication:
United States
Language:
English