We have studied the luminescence of narrow quantum wires at photoexcitation densities of up to ∼ 3×10 cm. We show that, even at these densities, which are well above the expected Mott density of 8 × 10 cm, excitonic recombination dominates over other recombination channels in stark contrast with the behavior of quantum wells and bulk structures at equivalent densities. As we observe no shift in...

The piezorefiectance technique has been used to optically characterize resonant tunneling structures that utilize isolated single quantum wells. The heavyand light-hole transitions associated with the quantum wells were prominent in the spectra of samples with barrier widths ranging from 50 to 34 A. Their spect.ral positions depended not only on quantum weB and barrier thicknesses, but also sig...

This study investigates the potential of Cl in tracing young groundwater with residence times of up to ~50 years. Groundwater samples were obtained from 16 irrigation wells in paddy fields located within an upland–lowland system in the Yoro River basin, Central Japan. The Cl/Cl ratios were in the range of 17 to 362  10. Among the samples with higher Cl concentrations (>10 mg/L), two samples sh...