Deep Ultraviolet Radiation Simulates the Turin Shroud Image

The faint yellowed body image embedded into the linen cloth of the Turin Shroud has peculiar chemical and physical characteristics that at the moment cannot be replicated all together in laboratory. The authors present experimental results of ArF excimer laser irradiation (wavelength 193 nm) of a raw linen fabric, seeking for coloration similar to that of the Shroud image. The authors achieved a permanent yellow coloration of linen as a threshold effect of the laser beam intensity and number of shots. Most important, the authors have achieved for the first time a submicrometer depth of coloration of the outermost part of the fibers, leaving a colorless fiber medulla. The authors also obtained latent coloration that appears after artificial aging of linen following laser irradiations that at first did not generate any visible effect. The authors have recognized different physical and chemical processes involved in both coloration and latent coloration. The comparison of the Turin Shroud image with the results of our ArF laser irradiation shows an interesting overlap of the main physical and chemical features.