Carbon / Carbon multilayer - A new approach in the development of nanometer-multilayer x-ray optics
The use of nanometer-multilayer X-ray optics induced a decisive extension of opportunities both in laboratory based X-ray analysis in the field of synchrotron radiation. With the growing number of different applications, more and more dedicated X-ray optics are required, optimized for the application and the spectral range they are intended to be used for. Both the characteristic of the used X-ray source and the design of the multiplayer optics finally define the performance of the conditioned incident beam for the application. Beside the regular two-component X-ray optical multiplayer which are characterized by widely different values of dielectric constants e (so called: high-Z / low-Z multiplayer), multiplay er consisting only of low-Z elements become more and more interesting in particular as high resolution X-ray optics. For the regular high-Z / low-Z multiplayer it is impossible to obtain both high reflectivity and high resolution simultaneously. This is mainly caused by a high absorption of X-ray radiation in the heavy absorber layers. By means of low-Z multiplayer these problems con be solved because of the low absorption materials which are used both for the absorber and the spacer layers in the multiplayer stack. Typical low-Z / low-Z material combinations are B4C/Si, Al2O3/B4C and C/ B4C. A special multiplayer structure of only one light low-Z material can be deposited by means of carbon layers with different modifications, for example. Due to the low absorption coefficient for X-rays in the range above 285 eV, such Carbon / Carbon multilayer have some considerabl e advantages in comparison with traditional Metal-Carbon multilayer.