Fast electrons energy loss spectrum

According to the data on energy-loss spectrum of fast electrons in thin layers of substance (see Section V.B.2), the most probable amount of lost energy is small, being 10-15 eV in dilute media and 20-25 eV in con-... 

Spectral data (Amax and AE, and e x 10 3) for the pyrimidine bases investigated in a few representative papers are collected in Table XXVIII. The absorption bands are denoted by the capital letters A, B, C, etc. In Table XXVIII we have listed the results of the vacuum ultraviolet measurements by Yamada and Fukutome428 (cf. also ref. 429), who measured the spectra of sublimed films of cytosine, thymine, uracil (and also of guanine and adenine) down to 120 nm at room temperature. Several remarkable absorption peaks were found below 190 nm in addition to the already known ones near 260 and 200 nm. A weak absorption at 230-240 nm in cytosine was not indicated in the sublimed films of the molecule,428 but was visible in the stretched polyvinyl alcohol film spectrum.432 Crewe et al.i3° studied the interactions of fast electrons with the five nucleic acid bases and measured the energy-loss spectra of 20 keV electrons transmitted through thin films of these bases. These last data are also listed in Table XXVIII for comparison with the other spectral findings. 

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