Machulin, V.F.; Motsnyi, F.V.; Peresh, E.Yu.; Smolanka, O.M.; Svechnikov, G.S.
(Физика низких температур, 2004)
The exciton reflection spectra of Cs₃Bi₂I₉ layered crystals is investigated in the temperature region
4.2–300 K with light polarization E ⊥ c. It is estimated that the energy gap Eg equals
2.857 eV (T = 4.2 K) and the ...