J. Biener et al., HREEL SPECTROSCOPY OF THIN ION-BEAM DEPOSITED C-H(D) FILMS, Journal of electron spectroscopy and related phenomena, 64-5, 1993, pp. 331-339
Several monolayers thick C:H films, H/C ratio ca 0.5, have been prepar
ed by ion beam deposition of hydrocarbons at a Pt(111)/C carrier. HREE
L spectra of films deposited at 350 K exhibit a rich structure in the
C-H stretch region around 3000 cm(-1) and fingerprint region below 160
0 cm(-1). The spectra confirm the presence of CH, groups at carbon in
sp, sp(2), and sp(3) hybridization states in a graphitic network. Vibr
ational spectra of deuterated films exhibit a normal isotope shift. Th
e nature of the deposited ion: ethane, ethylene, acetylene, benzene, h
as a negligible effect on the vibrational structure of the C:H films.
Annealing of the films up to 1250 K successively destroys sp, sp(3), a
nd sp(2) carbon related CH groups. Although the films are not crystall
ine, the angular distribution of the elastically scattered electrons i
s considerably peaked in the specular direction. The primary energy de
pendence of the V(C-H) vibration losses exhibits a resonance at 5 eV w
hich is considered as due to a marked impact mechanism contribution to
the respective spectral features.