The grafting of polystyrene (PS) onto various polypropylene (PP) containing substrates, previously treated by exposure to a plasma, has been followed by Raman microspectroscopic mapping. The substrates consisted of either pure PP, or blends of PP and ethylene-propylene rubber (EPR). For exactly the same section of polymer surface, Raman spectra were obtained at 1 micrometers intervals for small sections of each substrate, the surface after plasma-treatment, and the surface after PS grafting. Typically, the size of the sections studied was 50 micrometers X 50 micrometers . Raman maps were constructed indicating the crystallinity variation across the surface, and also the distribution of the EPR component in the substrate, and after plasma treatment. Raman maps were also constructed to show the distribution of the PS at the surface after the grafting reaction. Grafting was found to be heterogeneous. The overall amount of grafted PS depended on the amount of EPR in the substrate. For a particular substrate, increased concentrations of grafted PS were correlated with positions on the surface which had higher EPR after plasma treatment.

Raman spectroscopy was examined for ester ferroelectric liquid crystal D-4-(2-methylbutoxy)phenyl 4-decyloxybenzoate (MBOPDOB) to study configuration between s-cis and s-trans isomers and phase transitions between adjacent phases. Temperature behaviors were investigated for three low- frequency Raman modes at 15, 49 and 93 cm^-1. The 15 and 49 cm^-1 Raman lines vanish at crystal-Sm C* point and their temperature-cycle measurement gives 4 degree(s)C width of thermal hysteresis from crystal to Sm C*, which indicates first-order transition. Quasielastic scattering near the crystal-Sm C* point below 30 cm^-1 shows a critical slowing-down phenomenon relative to a long orientational relaxation in the Sm C* phase. The second-order property of the Sm C*-Sm A transition were proved by the facts that the 93 cm^-1 Raman line and spontaneous polarization go smoothly through the point, in addition a very small heat of the transition was recorded. Two conformations of COO group characterized by C equals O stretch mode at 1708 cm^-1 and C-O-C asymmetric stretch at 1177 cm^-1, the S-trans and s-cis isomers were found to coexist in the crystal phase. The S-trans isomer are transformed to the S-cis during the crystal-Sm C* transition and in the Sm A and isotropic phases. The larger dipole of the S-cis conformer is in favor of the formation of the ferroelectric phase.

A band at ca. 150 cm^-1 in the far infrared spectrum of diketopiperazine (DKP) is assigned to a ring puckering vibration. The multiplet structure reported for this band in the low temperature (77 K) far IR spectrum can be interpreted if the vibration is assumed to have quartic character. By means of Rayleigh-Schrodinger perturbation theory, a new vibrational selection rule, (Delta) n equals +/- 1, +/- 3, has been derived for mixed quartic-quadratic vibrations in the near harmonic region for the case of zero electrical anharmonicity. Assignments of the multiplet components have been made in the light of this vibrational selection rule. A two-parameter potential energy function of the ring puckering coordinate has been derived for the DKP molecule. This has enabled a value of ca. 355 cm^-1 to be estimated for the energy barrier to interconversion of enantiomeric boat forms of DKP. The 0 - 1 transition has been estimated to have a wavenumber value of 0.033 cm^-1 (1 GHz) in excellent agreement with the value of approximately 1 GHz obtained from a gas phase microwave spectroscopic study.

Spectroscopic method of zigzag chain molecules length determination from Raman spectra was developed. The method is based on measuring Raman lines frequencies, corresponding to acoustical modes and different optical modes of chain molecules. The excitation of Raman spectra was produced by continuous argon laser or by pulsed radiation from copper vapor laser.Raman spectra of hydrocarbon and fluorocarbon zigzag structure molecules have been studied. The investigations have been fulfilled for following substances: C_nH_2n+2 (n equals 6, 7, 10), C_nF_2n+1Br (n equals 6, 7, 8, 10, 14), C_nF_2n+2, C_nH_2nO₂ (n equals 4, 5, 8, 10, 11, 13, 15, 18). The frequency dependence of some Raman modes on the length of zigzag molecule has been observed. The theory, explaining this dependence, is developed. The obtained results allow estimating fluorocarbon and hydrocarbon molecules length from the Raman spectra parameters.

Raman scattering is a powerful technique for studying catalysts used in the treatment of automotive exhaust gas. It has the sensitivity and chemical specificity needed to identify the oxide phases of many of the precious metals (Pt, Pd, Rh) used in these catalysts, even when they are highly dispersed on high-surface-area supports such as (gamma) -Al₂O₃. Moreover, this technique can be employed in situ under temperature (300 - 600 degree(s)C) and pressure (1 atm) conditions typically encountered in normal operation. Bulk Pd oxide (PdO) is readily detected with visible excitation, because of a strong resonance Raman enhancement, and its formation and decomposition on Pd/(gamma) -Al₂O₃ and Pd/ZrO₂ catalysts can be followed in real time. Pt does not oxidize as easily as Pd, but a layer of atomic O will form on Pt, and it produces a Raman signature that can be detected with UV excitation at 244 nm. Similarly, UV excitation enhances spectra from adsorbed NO_x and SO_x and hydroxyls on model Pt/(gamma) -Al₂O₃ catalysts. In situ UV Raman spectra of Ba-containing catalysts, being considered for use as NO_x traps, show adsorbed NO_x and SO_x and, thus, can be used to characterize the NO_x trapping, S poisoning, and regeneration of the trap. UV excitation has several advantages in addition to the eletronic resonance enhancment: the signal is increased because of the dependence of the Raman cross section on the fourth power of the frequency, the fluorescence is often Stokes shifted well beyond the range of the Raman lines, and the thermal background from a heated sample is negligible.

Implementation of higher spectral and spatial resolution in dispersive Raman microscopes, including access to a variety of excitation wavelengths, has proven beneficial in the semiconductor industry. UV adaptations accommodate measurement of smaller defects, higher sensitivity to thin films (to the exclusion of the substrate) and access to enhancement conditions for materials such as GaN-based photodiodes and lasers, and diamond. The availability of a high dispersion spectrograph, especially for UV wavelengths, avoids compromising spectral resolution. Examples of successful analysis requiring longer focal length, mirror-based spectrographs are shown; these include stress in silicon-based devices, Raman and PL of InGaN (which provides information on composition) and carbon nanotube studies.

In this work, we report the behavior of the CdTe surface studied by micro-Raman. The micro-Raman measurements were performed with different laser lines in regions of both transparency and opacity, using infrared and visible lasers respectively. Visible radiation leads to the formation of Te on the irradiated surface compromising any conclusion about the presence of Te inclusions in CdTe, a subject of controversy. We show that the power density and local temperature is directly connected with the intensity of Te modes on the irradiated surface. In this context, the increase of excitation power and exposure time of the sample surface accelerates the process. We also show that the process is too fast to allow, in most cases, for real time characterization. Nevertheless in this work, it was possible to observe the growth of the Te optical modes during the measurement process by rigorous optical control of the beam characteristics and optical density. This result is the same in all random spectra obtained from different sample locations. We noticed that previously other authors irradiated CdTe and HgCdTe films with a nanosecond pulsed Ruby laser and attributed the decrease in electrical resistivity to the growth of a Te layer on the surface of the CdTe. Our work is a direct evidence for this result.

This presentation will focus on the development, optimization and use of a Raman spectroscopy immersion probe for the analysis of solid (powders, slurries, etc.) samples with emphasis on online process analysis applications. A novel high precision Raman probe for online process analysis will be described. The unique design of the Raman probe provides enhancements in measurement precision by increasing the reproducibility and accuracy of optical sampling of high solids content samples. The probe has been proven an effective sampling interface for the analysis of powders, suspensions, slurries, particles and solids. The ease of use of the Raman probe and the increased sampling precision has lead to its use in various proof of concept and online process analytical applications. These applications include dry powder-powder mixing efficiency, coating thickness measurements, solvent drying analysis, reaction monitoring and many other analytical processes. The physical and optical design of the Raman probe will be described and the applicability of the Raman probe as an online sampling tool will be demonstrated.

Nanocrystalline titania films were prepared by a complexing agent-assisted sol-gel dip-coating process. The effect of acetylacetone, diethanolamine and polyethylene glycol on the structure and morphology of the heat-treated titania films was examined by Raman and FTIR spectroscopy, x-ray diffraction and atomic force microscopy (AFM). The effect the complexing agents have on the anatase to rutile phase transition during the heat treatment process is studied. The understanding of this effect is expected to enhance our capacity to tailor the composition and morphology of films and thus their properties. The Raman and the infrared spectra of nanocrystalline titania films and the changes induced by the heat treatment were also investigated. We have studied the size of the crystallites in TiO₂ films and its dependence on the type of complexing agent used.

Silver oxide layers were prepared by reactive r.f. magnetron sputtering of a silver target in oxygen containing atmosphere. Spectroscopic analysis of the films revealed a gradually composition change from Ag over Ag₂O to AgO with increasing oxygen addition. Raman spectroscopy in combination with optical transmission measurements indicated that the AgO_x constituents readily decompose by laser irradiation to optically active silver scattering centers and oxygen. Surface enhanced Raman scattering (SERS) of carbon traces in the silver oxide layers verified the potential to excite local surface plasmons in such silver aggregates. Furthermore, SERS activity of the activated layers is demonstrated by the clear amplification of Raman bands of low concentrated chemicals. The example of the model molecule benzoic acid (BA) applied to AgO films on glass substrates allows to observe the activation process in situ. SER characteristics were found to be dependent on the silver oxide film constitution and the state of intermediate silver cluster formation along with the applied photoactivation-time and power.

Raman spectroscopy is used to study phonon confinement effect and photoluminescence (PL) for titanium dioxide nanocrystals. A chemical solution process was developed to prepare TiO₂ nanocrystals with particle sizes of 6.8 - 27.9 nm. As the grain size decreases, the lowest-frequency E_g mode at 152 cm^-1 shows blueshift and broadening. The frequency shift and line width broadening were theoretically studied at different grain sizes of 6.8, 10.3 and 27.9 nm under phonon confinement model, showing good agreement with experimental results. Non-stoichiometry effect was recorded by redshift of the 422 cm^-1 E_g mode, libration mode of the oxygen atoms along the c-axis. PL spectrum of the anatase TiO₂ nanocrystals was recorded at exciting power as low as 0.06 W/cm². A power-law relationship I_PL approximately equals P^(gamma ) was obtained between PL intensity and the excitation power. PL mechanism for TiO₂ nanocrystals is attributed to the recombination via the localized levels within the forbidden gap of defect-related centers, which reside in the surface region of TiO₂ nanocrystals.