First off, that's not what I asked. I asked why 405nm burns better than 635nm.
The question you asked is equivalent to asking why boiling water cooks something better (quicker), pasta for instance, than non boiling water, both the boiling water and the non boiling water contained molecules of H2O, but at different energy levels. Photons of violet light pack more energy per photon than red light photons same as boiling and non boiling water molecules. Violet photons transfer that energy to an object more effectively than red photons and it takes fewer violet photons to do so. All things being equal, spot size, output, surface color of object, between a violet laser and a red laser, violet light would still impart its energy quicker raising the temperature of the object it is shining on. The fact that violet light can be focused to a smaller spot size facilitates, but energy level is what really makes the difference.
I don't know myself, but you can google for an answer.Second, are UVB diodes available? Or something like 255nm? I don't know where UVA ends and UVB starts but just curious.