Origins of electronic band gap reduction in Cr/N codoped TiO2.

Recent studies indicated that noncompensated cation-anion codoping of wide-band-gap oxide semiconductors such as anatase TiO2 significantly reduces the optical band gap and thus strongly enhances the absorption of visible light [W. Zhu et al., Phys.

Local vibrational modes of isolated hydrogen in germanium.

Two distinct isolated hydrogen defects are observed in crystalline Ge by in situ infrared absorption spectroscopy. Implantation of protons into Ge at cryogenic temperatures gives rise to two intense absorption lines at 745 and 1794 cm(-1). The lines originate from distinct defects, each of which contains one H atom located on a <111> axis.

Vibrational lifetime of bond-center hydrogen in crystalline silicon.

The lifetime of the stretch mode of bond-center hydrogen in crystalline silicon is measured to be T1 = 7.8+/-0.2 ps with time-resolved, transient bleaching spectroscopy.