Anisotropy of electronic excitations in MoS2by low-energy electron angle-resolved loss spectroscopy

Abstract
Angle-resolved loss spectroscopy methods have been applied to study elementary excitations on molybdenum disulphide basal surfaces with incident electron energy in the range 50 to 250 eV. The lamellar structure of this compound results in inelastic process anisotropy. The authors have found: (i) interband transitions; (ii) a volume plasmon with p perpendicular to c at 8.8 eV; (iii) an excitation p//c at 7 eV, tentatively interpreted as Tosatti 'anisotron'; (iv) a collective excitation which may be a surface plasmon at 18 eV; (v) two volume plasmons (p perpendicular to c and p//c) at 24 eV.