Absence of evidence of superconductivity in sulfur hydride in optical reflectance experiments

Capitani and coworkers reported that infrared optical reflectance measurements provided evidence for a superconducting transition in sulfur hydride under 150 GPa pressure, and that the transition is driven by the electron-phonon interaction. Here we argue that the measured data did not provide evidence that the system undergoes a transition to a superconducting state, nor do the data support any role of phonons in driving a transition. Rather, the data are consistent with the system remaining in the normal state down to temperature 50K, the lowest temperature measured in the experiment. This calls into further question the generally accepted view that sulfur hydride under pressure is a high temperature superconductor.