Quasi-Moseley's law for strong narrow bandwidth soft x-ray sources containing higher charge-state ions

Bright narrow band emission observed in optically thin plasmas of high-Z elements in the extreme ultraviolet spectral region follows a quasi-Moseley's law. The peak wavelength can be expressed as λ=(21.86±12.09)×R∞−1×(Z−(23.23±2.87))−(1.52±0.12), where R∞ is the Rydberg constant. The wavelength varies from 13.5 nm to 4.0 nm as the atomic number, Z, increases from Z = 50 to Z = 83. The range of emission wavelengths available from hot optically thin plasmas permits the development of bright laboratory-scale sources for applications including x-ray microscopy and x-ray absorption fine structure determination.