On the Reflection of theKαLine of Carbon from a Glass Mirror

Abstract

The author recalls previous experiments which he tried in order to determine the limiting angle of total reflection from a glass grating, for a set of radiations between 20 and 65A, making a slight correction to a recent work of E. Dershem on the reflection of the $K\ensuremath{\alpha}$ line of carbon. In the case of glass, with $\ensuremath{\lambda}=44.9$A, if we take into account the discontinuities of absorption in the dispersive medium, the Kallman-Mark dispersion formula leads us to a result ($\ensuremath{\delta}=1\ensuremath{-}n=5.73\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$) of the same order as the Drude-Lorentz simplified formula. The reflected intensity from the mirror is calculated from the angle of incidence, account being taken of the absorption. The result is then compared with the experimental curve given by Dershem for the $K\ensuremath{\alpha}$ line of carbon, and shows that it is possible to determine the critical angle of total reflection from glass (${\ensuremath{\theta}}_{m}=6\ifmmode^\circ\else\textdegree\fi{}{12}^{\ensuremath{'}}$) and the refractive index ($\ensuremath{\delta}=1\ensuremath{-}n=5.84\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$).