The role of A in ARPES

Angle-resolved photoemission spectroscopy (ARPES) was developed in the 1970s to 1990s as a momentum-resolved probe of the electronic structure of solids, with its basic principles summarized in early seminal works and classic reviews. The basic ARPES result is currently almost exclusively associated with the two-dimensional intensity distribution with coordinate axes labeled as `Binding energy' and `Momentum'. Such datasets are usually directly compared with band structure calculations along high symmetry directions of the Brillouin zone. Here it is shown that this is the result of an oversimplified treatment of the ARPES data leading to incorrect interpretations of the experimental results. Practical ways of how to avoid this in both data collection and analysis are suggested.