Vacuum UV Fluoride

Patent Granted Vacuum UV or VUV (wavelengths shorter than 200 nm) is blocked by air but can propagate through a vacuum. These wavelengths are strongly absorbed by molecular oxygen in the air. Pure nitrogen (with less than about 10 ppm oxygen) is transparent to wavelengths in the range of about 150 – 200 nm. This has practical significance, since semiconductor manufacturing processes have been using wavelengths shorter than 200 nm. By working in oxygen-free gas, the equipment does not have to be built to withstand vacuum. Some other scientific instruments that operate in this spectral region, such as circular dichroism spectrometers, are also commonly nitrogen-purged.