中央研究院 原子與分子科學研究所

Two-photon photoemission (2PPE) spectroscopy on NiTe₂ is performed by the combination of femtosecond ultraviolet laser pulses with time-of-flight photoelectron momentum microscopy. At the photon energies of 2.9 and 3.1 eV, the bulk Te 5p_z valence bands as well as the spin–orbit split Te 5p_x,y valence bands are identified. Detailed momentum patterns of the Te 5p_x,y bands are revealed, and the size of their splitting is estimated as 0.5^+0.2_-0.1 eV. Our 2PPE experiments on NiTe₂ would open up the opportunities for future time-resolved studies of its unoccupied electronic states.