LOW-ENERGY ELECTRON-ENERGY-LOSS SPECTROSCOPY OF SOLID METHANOL - VIBRATIONAL AND ELECTRONIC EXCITATIONS

We report electron-energy-loss spectra for 19-eV electrons incident on a solid film of methanol (30 layers) condensed at 15 K. The vibration al energy losses compare more closely to the infrared absorption spect rum of solid methanol in its amorphous phase. The first electronic exc itation is found around 7.7 eV with a threshold at 6.7 eV. It Is follo wed by a weak band around 9.5 eV. These two excitation features are id entified to the gas-phase transitions (3,1)A'' (2a''-->3s) and (3,1)A' (7a'-->3s), blueshifted by 1.0-1.4 eV in the condensed phase. At high er energy loss, we have a large maximum around 15.5 eV due to various transitions from the ground state to free-electron conduction bands an d to the ionization cross section of the solid.