This study investigates alginate-chitosan polyelectrolyte complexes (PECs) in the form of a film, a precipitate, as well as a layer-by-layer (LbL) assembly. The focus of this study is to fully characterize, using the complementary techniques of Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) in combination with solution stability evaluation, the interactions between alginate and chitosan in the PECs. In the FTIR spectra, no significant change in the band position of the two carbonyl vibrations from alginate occurs upon interaction with different ionic species. However, protonation of the carboxylate group causes a new band to appear at 1710 cm(-1), as anticipated. Partial protonation of the amine group of chitosan causes the appearance of one new band ( approximately 1530 cm(-1)) due to one of the -NH3+ vibrational modes (the other mode overlaps the amide I band). Importantly, the position of the two main bands in the spectral region of interest in partly protonated chitosan films is not dependent on the extent of protonation. XPS N 1s narrow scans can, however, be used to assess the degree of amine protonation. In our alginate-chitosan film, precipitate, and LbL assembly, the bands observed in the FTIR correspond to the species -COO- and -NH3+, but their position is not different from each of the single components. Thus, the conclusion of the study is that FTIR cannot be used directly to identify the presence of PECs. However, in combination with XPS (survey and narrow N 1s scans) and solution stability evaluation, a more complete description of the structure can be obtained. This conclusion challenges the assignment of FTIR spectra in the literature.

Azurite [Cu2+ 3 (CO 3 ) 2 (OH) 2 ] and malachite [Cu 2+ 2 (CO 3 )(OH) 2 ] are both monoclinic hydroxy carbonates of copper. The Raman spectra of these two minerals were collected at both 298 and 77 K together with the single crystal Raman spectra of azurite at 298 K. The spectra of both azurite and malachite contain modes of three separate vibrational groups: OH, CO 3 and Cu-O. Accordingly, for azurite the bands at 3453 and 3427 cm −1 have been assigned as the O-H stretching mode with the O-H bending modes found at 1035 and 952 cm −1 . Malachite displays two hydroxyl stretching bands at 3474 and 3404 cm −1 at 298 K which shift to 3470 and 3400 cm −1 at 77 K while O-H out-of-plane bending modes are found at 1045 and 875 cm −1 . For the carbonate group, bands are observed at 1090 cm −1 (n 1 ), 837 and 817 cm −1 (n 2 ), 1490 and 1415 cm −1 (n 3 ) and 769 and 747 cm −1 (n 4 ). The effect of collecting the spectra at 77 K results in considerable band narrowing. The Raman spectra of the single crystals of azurite show the orientation dependence of the vibrational modes. A mechanism for n 2 splitting is proposed whereby vertical carbonate ions couple to form an in-phase and out-of-phase bending modes. Combination of these vibrational modes such as n 1 + n 3 , n 1 + n 3 , n 1 + n 4 and 2n 2 are found at 2530, 2414, 1860, and 1670 cm −1 , respectively. IR bands for the Cu-O stretching modes are observed at 495 and 400 cm −1 , while Cu-O bending modes occur at 455 and 345 cm −1 . Bands at 305 and 240 cm −1 are assigned to the O-Cu-OH bending modes. The Raman out-of-plane bending modes are found at 194 and 170 cm −1 . For the carbonate group, infrared bands are observed at 1095 cm −1 (n 1 ), 834 and 816 cm −1 (n 2 ), 1430 and 1419 cm −1 (n 3 ) and 764 and 739 cm −1 (n 4 ). Combination of the CO 3 vibrational modes n 1 + n 4 is observed at 1860 cm −1 . IR bands for Cu-O stretching modes are observed at 580, 570 and 505 cm −1 .

Polarisation Raman microscopy is used to study tubular chrysotile. The OH-stretching region is characterised by the inner surface OH bands at 3695, 3686 and 3678 cm~1 and the inner OH band at 3643 cm~1. The outer OH pointing away from the Mg-layer gives rise to two overlapping bands at 3695 and 3686 cm~1 due to a positional disorder caused by the folding of the layers. These bands are the in-phase vibrations whereas the bands at 3678 and 3643 cm~1 represent the out-of-phase vibrations. The 1102 cm~1 band is an antisymmetric stretching mode of SiÈO perpendicular to the sheet. From the 692 and 705 cm~1 bands the Ðrst one is assigned to the symmetric SiÈOÈSi stretch and the second to an outer symmetric translation mode of the MgÈOH oriented sub-parallel to the a-axis. The 709 cm~1 band is assigned to the second outer symmetric translation mode of the MgÈOH oriented at a small angle to the b-axis and c-axis. The 629 and 622 cm~1 bands represent antisymmetric OHÈMgÈOH translation modes. The band around 607 cm~1 is described as the symmetric libration mode of the inner MgÈOH group. The 458 cm~1 band is assigned as the mode of The v 3 (a 1 ) SiO 4 . 466 cm~1 band is probably an OH translational vibration. A strong band at 388 cm~1 is ascribed to the antisymmetric mode of the tetrahedron. The band at 432 cm~1 is assigned as an antisymmetric v 5 (e) SiO 4 MgÈOH translation mode. In the region between 450 and 200 cm~1 Ðve bands can be observed at 374, 345, 318, 304 and 231 cm~1. The 374, 318 and 304 cm~1 bands are antisymmetric modes, whereas the 345 and 231 cm~1 bands are symmetric modes. The band at 374 cm~1 is associated with a symmetric MgÈOH vibration. At present a more detailed assignment of the other bands is not possible. The band at 199 cm~1 is assigned to the mode of a Mg(O,OH) octahedron distorted in the direction normal to the octahedral sheet. A 1g 6Paper 8/09238I

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Polyacrylamide gels (PAGs) are used for magnetic resonance imaging radiation dosimetry. Fourier transform (FT) Raman spectroscopy studies were undertaken to investigate cross-linking changes during the copolymerization of polyacrylamide gels in the spectral range of 200-3500 cm(-1). Vibrational bands of 1285 cm(-1) and 1256 cm(-1) were assigned to acrylamide and bis-acrylamide single CH2 deltaCH2 binding modes. Bands were found to decrease in amplitude with increasing absorbed radiation dose as a result of copolymerization. Principal component regression was performed on FT-Raman spectra of PAG samples irradiated to 50 Gy. Two components were found to be sufficient to account for 98.7% of the variance in the data. Cross validation was used to establish the absorbed radiation dose of an unknown PAG sample from the FT-Raman spectra. The calculated correlation coefficient between measured and predictive samples was 0.997 with a standard error of estimate of 0.976 and a standard error of prediction of 1.140. Results demonstrate the potential of FT-Raman spectroscopy for ionizing radiation dosimetry using polyacrylamide gels.

1H‐ and 13C‐NMR spectroscopy and FT‐Raman spectroscopy are used to investigate the properties of a polymer gel dosimeter post‐irradiation. The polymer gel (PAG) is composed of acrylamide, N,N′‐methylene‐bisacrylamide, gelatin, and water. The formation of a polyacrylamide network within the gelatin matrix follows a dose dependence nonlinearly correlated to the disappearance of the double bonds from the dissolved monomers within the absorbed dose range of 0–50 Gy. The signal from the gelatin remains constant with irradiation. We show that the NMR spin–spin relaxation times (T2) of PAGs irradiated to up to 50 Gy measured in a NMR spectrometer and a clinical magnetic resonance imaging scanner can be modeled using the spectroscopic intensity of the growing polymer network. More specifically, we show that the nonlinear T2 dependence against dose can be understood in terms of the fraction of protons in three different proton pools. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1572–1581, 2001

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Amine functionalities were introduced onto the surface of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) films by applying radio frequency ammonia plasma treatment and wet ethylenediamine treatment. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS) for chemical composition and Raman microspectroscopy for the spatial distribution of the chemical moieties. The relative amount of amine functionalities introduced onto the PHBV surface was determined by exposing the treated films to the vapor of trifluoromethylbenzaldehyde (TFBA) prior to XPS analysis. The highest amount of amino groups on the PHBV surface could be introduced by use of ammonia plasma at short treatment times of 5 and 10 s, but no effect of plasma power within the range of 2.5-20 W was observed. Ethylenediamine treatment yielded fewer surface amino groups, and in addition an increase in crystallinity as well as degradation of PHBV was evident from Fourier transform infrared spectroscopy. Raman maps showed that the coverage of amino groups on the PHBV surfaces was patchy with large areas having no amine functionalities.