 Harder UV radiation is detrimental to the production of KrF2.Using Pyrex glass or Vycor or quartz will significantly increase yield because they all block harder UV light.In a series of experiments performed by S. A Kinkead et al., it was shown that a quartz insert (UV cut off of 170 nm) produced on average 158 mg/h, Vycor 7913 (UV cut off of 210 nm) produced on average 204 mg/h and Pyrex 7740 (UV cut off of 280 nm) produced on average 507 mg/h.