Ultraviolet photoelectron spectroscopy (UPS)
The most frequent approach for measuring the entire spectrum of the electron density of states DOS on both inorganic and organic materials is ultraviolet photoelectron spectroscopy (UPS), which has already been utilized for organic small molecules such as pentacene.
The method of photoelectron spectroscopy (PES) is used to determine the ionization potentials of molecules. PES encompasses two distinct methodologies for quantitative and qualitative assessments. UV photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) are the two methods (XPS). XPS was previously known as electron spectroscopy for chemical analysis (ESCA). UPS concentrates on valence electron ionization, whereas XPS may go a step farther and ionize core electrons and rip them away.
Ultraviolet photoelectron spectroscopy (UPS), which uses low-energy photons (often HeI, 21.2 eV, and HeII, 40.8 eV), is important for analyzing the valence band structures and electronic features of various sources and validating band structure models.