It is shown that the intensity of the electronic current backscattered from the surface is the convolution product of the total reflection coefficient by the energy distribution of the incident beam. A deconvolution method has been used to obtain this coefficient and this method is based on a rigorous inversion of the convolution integral operator. Numerical tests show that this method is not very sensitive to the experimental random noise. Results are given for W(100), Cu(100), and O/Cu(100) surfaces, and these are correlated with earlier measurements.
In surface studies, the mirror electron microscope (MEM) can give a picture of electrical and geometrical roughness and simultaneously a continuous measurement of local work-function changes Delta phi ; however, no critical study has been done on the accuracy of such a measurement. Using the MEM, the authors developed a new method to obtain the total electron reflection coefficient R in the very low energy range which allows them to determine accuracy and exhibit some correlations between Delta phi measurements and R variations near zero energy. By using a local deconvolution treatment for our experimental results on O/W (100), O and CO/Ni(111) and O and CO/Cu(100) the authors determined the injection threshold for monokinetic electrons. The results lead the authors to present a new sequential operating method giving R which is of great interest in the low energy range and a Delta phi measurement with controlled accuracy.
The study of the laser induced desorption suggests to associate this technics to the mirror electron microscopy for measuring the work function changes and the total electron reflection coefficient at a metallic surface, during the sample desorption. The results are concerned with W (100) single crystal samples. A pulsed ruby laser light is used with an energy in the range 0.01 to 3 J. The measurements are performed with a mirror electron microscope, using very slow electrons (0 to 5 eV) in the vicinity of the surface sample. The apparatus is inside an ultrahigh vacuum chamber (10−9 to 10−10 Torr); a quadrupole mass spectrometer (QMS) may either be used as a detector of laser produced ions or as a residual gas analyzer; a microprocessor associated to a lock‐in amplifier stores I(U) and dI(U)/dU (where I and U are respectively the backscattered electron current and the bias voltage of the sample); the use of a deconvolution treatment eliminates the effect of the electron spread of the incident electrons. So, the reflection coefficient can be measured after laser irradiation: the values observed show the efficiency of the laser desorption.
AMPERE is a programming language devoted to physical sciences. In order to increase the reliability of scientific programs this language integrates dimensional analysis, units handling and interval computations. Furthermore AMPERE achieves extensibility through the use of split identifiers for the subroutine's names, modular programming with genericity, and the capability of building various physical environments by derivation. Thus it leads to clear programs and remains easy to learn and to adapt.
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