Konopsky V.N., Sekatskii S.K., Letokhov V.S.
Laser photoelectron projection microscopy with subwavelength spatial resolution. // Appl.Surf.Sci., 1996, V.94/95, P.148-155.

The development of a laser photoelectron projection microscope with a magnification up to $10^5$ and spatial resolution up to $30\; nm$ as well as the first results of studies of needle tips made of $LiF$ crystals with $F_2$-aggregated centers with the use of this microscope are reported. The resolution achieved was sufficient to visualize individual defects on the crystals surface. The effects of thermal faceting of $LiF:F_2^-$ needle tips due to their heating by intense laser radiation were observed for the first time.


Fig.1 Scheme of the laser photoelectron projection microscope.


Fig.2 A photoelectron image of the $LiF:F_2$ needle tip with the concentration of $F_2$-centers $n\simeq 10^{16}\; cm^{-3}$. The radius of the needle tip $r\simeq 600\; nm$; the tip is irradiated by all the lines of $Ar^+$ laser with the intensity $I\simeq 5\cdot 10^3\; W/cm^2$.