Determination of deformation potentials by three-photon piezoabsorption of paraexcitons in KI

Abstract
Three-photon piezoabsorption of paraexcitons is introduced as a method for the determination of deformation potentials. The splitting of the fivefold paraexciton in KI is clearly resolved for uniaxial stress up to 800 bar. The hydrostatic, tetragonal, and trigonal deformation potentials are determined with much higher accuracy than is possible with the classical method of piezoreflection.