Photoconductivity and electron transport parameters in liquid and solid xenon

In photoconductivity excitation spectra of liquid xenon a threshold at 9.20 eV and a dip at 9.45 eV, very near to the peak of the competing n=1 [Γ(1/2)] exciton transition, were observed. From the results the Γ(3/2) band gap was determined to be EG=9.22±0.01 eV. This value is very near to the estimate (9.24 eV) based on the density change of xenon on melting. Combining the value for EG with the measured position of the n=2 [Γ(3/2)] exciton peak yielded an exciton binding energy $G=1.08$ eV and effective exciton reduced mass m*=0.27 (in units of electron mass). Using m* and published results of the bulk modulus and mobility, the following parameters were obtained for liquid Xe at 163 ^∘{}K: relaxation time τ=3.4×10^-13 sec, mean free path L=3.3×10^-6 cm, absolute value of scattering length |a|=4.2×10^-9 cm, absolute value of conduction-band deformation potential |E1CB|=1.0 eV. On the other hand, for solid xenon at 161 ^∘{}K τ=8.0×10^-13 sec, L=7.1×10^-6 cm, |a|=3.8×10^-9 cm, and |E1CB|=0.93 eV. The significance of the results is discussed.