Tip-related electronic artifacts in scanning tunneling spectroscopy

The electronic spectrum of the probe tip is found to play a crucial role in measurements of scanning tunneling spectroscopy. Tips with a nonuniform density of states can produce highly convoluted I-V curves, even if they produce atomic-resolution topographic images. In some cases, tips with a strongly peaked density of states away from the Fermi level can shift the apparent energy of spectral features of the sample by as much as 1 eV. © 1991 The American Physical Society.