High-resolution isochromat inverse photoemission spectroscopy

We propose a new method to measure the vacuum ultraviolet inverse photoemission spectrum in an isochromat mode with high resolution. In this new method, two filters (F1 and F2) with slightly different cutoff energies h ν 1 and h ν 2 ( h ν 1 < h ν 2 ) are used as the window for measurement. The transmittance of the two filters is assumed to be equivalent except for the region of h ν 1 ∼ h ν 2 . The spectrum measured by F1 is properly normalized and subtracted from the spectrum obtained by F2. The resulting difference spectrum provides the inverse photoemission spectrum measured with high resolution defined by h ν 2 - h ν 1 , which can be better than 0.2 eV.