Raman spectroscopy of phenylcarbyne polymer films under pulsed green laser irradiation

Abstract

Raman scattering as a probe of morphology in conjugated polymer thin filmsThe polycarbyne polymer films were coated on silicon substrates and then irradiated by a pulsed Nd:yttrium-aluminum-garnet laser ͑ϭ532 nm͒ with various fluences in argon gas atmosphere. Significant changes in microstructures and chemical bonding (sp 3 /sp 2 ) during laser treatment were investigated by Raman spectroscopy. At a laser fluence below 50 mJ/cm 2 , the Raman spectrum of the film was similar to that of the original polymer film. In a fluence range from 100 to 650 mJ/cm 2 , the thermal decomposition of the polymer occurred, resulting in upshift of G peak and downshift of the D peak both with narrower peak width. With increasing laser fluence from 650 to 950 mJ/cm 2 , both the G and D peaks downshifted simultaneously due to the thermal decomposition. The simultaneous downshift of both peaks indicated the increased sp 3 /sp 2 ratio in the carbon film converted from the polymer. With increasing laser fluence in this range, the thermal decomposition also induced the narrowing of both peaks. The narrowing of both peaks indicated the increased ordering of sp 3 and sp 2 bonding components in the converted carbon film. The scanning electron microscopy studies provided the further evidence. The carbon films converted from the polymer films may contain the highest sp 3 carbon bonding at laser fluences in the range from 850 to 1000 mJ/cm 2 .

Synthesis and characterization of nickel-doped diamond-like carbon film electrodeposited at a low voltage

“…Rerrari and Robertson [19] found that the D peak intensity decreased with increasing disorder in amorphous carbon; the width of the G peak was proportional to the bond-angle disorder at sp2 sites, and the mixing with sp3 modes helped to lower the G peak intensity in hydrogenated amorphous carbon (a-C:H). They also found that the sp3 content increased with the simultaneous decrease of G-peak position and I D /I G ratio in a-C:H. Therefore, it can be inferred that the Ni-doped DLC film should have a higher content of sp3 carbon than the undoped DLC film [19,22]. Fig.…”

A novel method for the preparation of amorphous hydrogenated carbon films containing Au nanoparticles

“…In every spectrum two broad peaks are observed at approximately 1344 and 1597 cm À1 , referring to the D-line and G-line, respectively. It is well known that large single-crystal graphite and highly oriented pyrolytic graphite (HOPG) display a single sharp peak (G band), disorder or fine graphite crystallites show an additional disorder peak (D band) [19]. Therefore, we believe that the structure of the carbon films obtained in our system is amorphous.…”

In vitro cytocompatibility evaluation of hydrogenated and unhydrogenated carbon films

“…To analyze the structure of a-C film and a-C: H film, the spectra were then processed by linear background subtraction and Gaussian curve fitting with limit of less than 400 cm − 1 full width at half maximum (FWHM). It is well known that the additional disorder peak at about 1335 cm −1 (D band) displays disordered or fine graphite crystallites, while the single sharp peak at about 1580 cm −1 (G band) is the presentation of large single-crystal graphite and highly oriented pyrolytic graphite [23]. The relative intensity of the disorder-induced D peak to that of the G peak (I D /I G ) is related to the graphitic content and sp 3 fraction [23,24].…”

“…It is well known that the additional disorder peak at about 1335 cm −1 (D band) displays disordered or fine graphite crystallites, while the single sharp peak at about 1580 cm −1 (G band) is the presentation of large single-crystal graphite and highly oriented pyrolytic graphite [23]. The relative intensity of the disorder-induced D peak to that of the G peak (I D /I G ) is related to the graphitic content and sp 3 fraction [23,24]. As shown in Table 1, for a-C film, the D band is at 1343.1 cm −1 and G band is at 1559.4 cm −1 with I D /I G ratio of 1.99.…”