X-ray photodesorption intensities (divided by the photon flux) associated with the m/z channels monitored during the irradiation at fixed energies from pure HCOOH ice and mixed ¹³CO:HCOOH and H₂O:HCOOH ices. These intensities were derived at 560 eV and for an irradiation at 15 K. The photon fluence received by the ice before the measurements varies between ~4 × 10¹⁵ and ~3 × 10¹⁶ photons cm⁻².