TABLE 2 Peak Assignments for the PDS-Derived Absorption Spectra of LDPE, PEEK,

Here, a and b can be used as fitting parameters in a linear plot of v ^ J n against n. The results of plots of v ^ J n against n for polyimide are shown in Fig. 13. From the linear regression, the fundamental absorption frequencies can be obtained. The extrapolated fundamental absorption frequencies are around 3.3 /mm (3030 cm-1) for the aliphatic C -H stretching vibration and 3.2 pm (3125 cm-1) for aromatic C -H stretching vibration. These frequencies are consistent with the results obtained from standard infrared spectroscopy. The anharmonicity coefficients are typically less than 4%. The fitting parameters obtained for different polymer films are shown in Table 2.