Franck-Condon–Broadened Angle-Resolved Photoemission Spectra Predicted inLaMnO3

The sudden photohole of least energy created in the photoemission process is a vibrationally excited state of a small polaron. Therefore the photoemission spectrum in ${\mathrm{LaMnO}}_3$ is predicted to have multiple Franck-Condon vibrational sidebands. This generates an intrinsic line broadening $\approx 0.5\mathrm{eV}$. The photoemission spectral function has two peaks whose central energies disperse with bandwidth $\approx 1.2\mathrm{eV}$. Signatures of these phenomena are predicted to appear in angle-resolved photoemission spectra.