In the paper
Characteristics of 2-photon ultraviolet laser etching of diamond. RP Mildren et al. Opt. Mater. Express 1, 576 (2011),
I found out that UV light cause the atom ejection from the surface of diamond. According to the article, the process is caused by the presence of UV light and there's no threshold meaning that the loss of mass will happen even under sunlight. My question is: if there's no threshold, does that mean that the process will happen even under visible light in standard irradiance or there's definitely necessary to have UV rays? Thank you.