Ion Irradiation of Solid Carbons - Polyynes: Synthesis, Properties, and Applications - page 271

FIGURE 13.4 IR spectra (in optical depth units) of asphaltite (3400-1900 cm 1 )
taken at 200K before (dotted line) and after (solid line) ion irradiation (1.8 10 16
30 keV He þ cm 2 ). After the collection of the spectrum of the as prepared sample
(dotted line) a new background has been taken that includes the sample itself. Thus
newly formed bands are seen as having positive optical depths; bands with negative
optical depths are those of asphaltite that is progressively destroyed.

Asphaltite exhibits several vibrational absorption bands mostly due to
aliphatic and aromatic functional groups. The spectral range investigated
here is 3700-1900 cm 1 . In such a range, the most prominent bands are
those due to the aliphatic and aromatic C-H stretchings.
Figure 13.4 shows two spectra of asphaltite taken at 200K before
(dotted line) and after (solid line) 10 16 30 keV

He þ cm 2 ). After the collection of the spectrum of the as prepared sample
(dotted line in Figure 13.4) a new background has been taken that includes
the sample itself. In this way, after irradiation, newly formed bands are seen
as having positive optical depths. Bands with negative optical depths are
those of asphaltite that is progressively destroyed by ion irradiation. We can
see the appearance of newly synthesized bands. The most intense are those
at 3301 cm 1 and 2106 cm 1

ion irradiation (1.8

that are attributed to C-H and C C stretch-

ings in R-(C C)-H systems. The appearance of these bands testifies for the

ion-induced synthesis of carbynoid structures.