Vibrational Spectroscopic Study of Iodine-Doped Poly(Isothianaphthene)

Abstract

Far-infrared, mid-infrared, and Raman spectroscopy were used to characterize iodine-doped poly(isothianaphthene) (PITN) films and powders. The far-infrared and mid-infrared results show changes from absorption mode to reflective mode as the doping level increases, consistent with the iodine-doped PITN becoming more metallic and more conductive at higher doping levels. The far-IR and Raman (514.5-nm laser excitation) results show that I3− is dominant in iodine-doped PITN. The Raman spectral changes observed using 1064-nm excitation are different from those measured using 514.5-nm excitation. The spectra recorded with 514.5-nm excitation show features due to the undoped parts of the polymer, and these indicate that the effective conjugated chain length decreases with increased doping. The Raman spectra obtained by using 1064-nm excitation show features due to polaron and bipolaron states in the doped polymer.

Electronic states of the DNA polynucleotides poly(dG)-poly(dC) in the presence of iodine

“…Two Raman bands, observed below 400 cm −1 , are attributed to the second and third harmonics of the symmetric stretching mode ͑ 1 Ϸ 107 cm −1 ͒ of I 3 − , i.e., 2 1 and 3 1 ͑"Region X" in this figure͒, respectively. 56,57 Although the 1 band cannot be detected directly because the notch filter cuts off the light below ϳ200 cm −1 , the observed 2 1 and 3 1 bands clearly indicate again that iodine is in the form of I 3 − ion in iodinedoped poly͑dG͒-poly͑dC͒, as described in the previous section ͓see the I 3d levels characterized with x-ray PES; Figs. 1͑b͒ and 1͑c͔͒.…”

“…The presence of dopant was also confirmed by the Raman bands arising from the vibration modes of anionic iodine species. 56,57 In Sec. III B, we show Raman spectra of iodinedoped poly͑dG͒-poly͑dC͒ with various doping levels, and discuss the radical site strongly affected by the doping.…”

An electron paramagnetic resonance study of poly(isothianaphthene)

“…1(a) shows a sharp band centered at 3347 G (g ¼ 2.0058) with a peak-to-peak linewidth of 6 G, which is considered to be derived from a combination of polarons and neutral p-radicals. 21 This is consistent with the results of Raman studies, 17 elemental analysis 16 and conductivity measurements (see below). Thus, the PITN powder was dedoped with hydrazine and the EPR spectrum of the dedoped powder shown in Fig.…”

“…The iodine content of the iodine-doped PITN was measured independently by X-ray photoelectron spectroscopy (XPS) and by elemental analysis. 17…”

Synthesis and properties of a low-bandgap liquid crystalline π-conjugated polymer

“…The absorption bands at 1613 cm 1 and 1585 cm 1 are due to C=C stretching of the benzene ring. The absorption at 1430 cm 1 may be due to CH bend and CH stretching in the benzene ring of the ITN unit [17,18].…”