The article offers a report related to a study which demonstrates the concentration of electrons and the size of the unit cell for iron-based superconductors. It informs that the study was performed for a single monolayer of iron selenide (FeSe) deposited on strontium titanate (SrTiO3). It further informs that the structure of FeSe in detail and by the energy (E) and momentum (k) distributions of the electrons were recorded.