Lunar Luminescence

Hello everyone
I have long been interested in eclipses of the Moon, and now in particular in the brightness of the Moon in penumbra. Old observations of this phenomenon indicate a greater brightness of the Moon in penumbra than expected. Astronomer Link attributed this excess light to the luminescence of the lunar soil caused by the X-ray and UV radiation emitted by the solar corona and chromosphe. Unfortunately, I cannot find any recent articles, or chapters in any books, that deal with this subject? It seems that this has been abandoned for several decades. Perhaps everything has already been explained?
That is why I would ask for help. Could someone give me a bibliographic indication, or even a contact to people who might be familiar with this lunar problem?
Thank you