The peak can be shifted from 100 to 105 nm and probably beyond.
The coating can be adapted to reflect key spectral lines for solar physics and astrophysics, such as Lyman β at 102.6 nm and the OVI doublet at 103.2 & 103.8 nm, and to reject (absorb) ubiquitous Lyman α line at 121.6 nm.
The coating combines layers of Al, LiF, and SiC, and it combines deposition by evaporation (Al and LiF) with Ion-Beam Sputtering (SiC). The outermost layer is LiF.
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Coatings are based in a multilayer coating that alternates two fluoride materials. Typical materials for this spectral range are LaF2 and GdF2 with large refractive index and MgF2 and AlF3 with low refractive index.
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All materials in nature involve a strong absorption of EUV wavelengths in the ~60-100 nm. Several attempts were made at GOLD to develop narrowband coating multilayers based on lanthanide materials.
The figure displays a band peaked at ~80 nm with a multilayer based on Al, Eu, and SiO.
Multilayer tuned at ~ 80 nm based on Eu, Al, and SiO.
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