Infrared optical properties and AFM of spin-cast chitosan films chemically modified with 1,2 Epoxy-3-phenoxy-propane

Chemical modification of spin-cast chitosan films has been performed. This modification involves the attachment of 1,2 Epoxy-3-phenoxy-propane, commonly known as glycidyl phenyl ether (GPE), to the amine group of the chitosan molecule. Optical properties of modified films have been determined in the infrared region of the spectrum using spectroscopic ellipsometry, and are reported in this paper. Special attention is paid to the infrared region where the index of refraction and extinction coefficients from 750 to 4000 cm(-1) were determined. Difference plots of IR optical data before and after chemical modification were generated to confirm that modification had occurred. Optical modeling of infrared spectroscopic ellipsometry (IRSE) data with respect to chemical bond vibrations has also been performed. This modeling involved curve fitting of resonant chemical bond absorptions using Lorentz oscillators. These oscillator models allow for comparison of modified chitosan to unmodified chitosan. The purpose of this research was to determine infrared optical constants of chemically modified chitosan films This work shows that surface chemistry of biomaterials can be studied quite sensitively with spectroscopy ellipsometry, detecting as little as 100 ng/cm(2) of GPE.     

UV-vis-infrared optical and AFM study of spin-cast chitosan films

Optical properties of spin-cast chitosan films have been determined in the infrared, visible, and ultraviolet region of the spectrum using spectroscopic ellipsometry. Optical constants for the UV–vis–near IR spectra from 130 to 1700 nm were determined using Cauchy dispersion forms combined with Lorentzian oscillator models in the absorptive shorter wavelength regions. Infrared index of refraction and extinction coefficients from 750 to 4000 cm⁻¹ were determined using ellipsometric data fits to dispersion models based on harmonic oscillators. This modeling determined that optical anisotropy was present and measurable over all wavelength regions of ellipsometric data.

To obtain information on the micro- and nano-scale surface structure, tapping mode atomic force microscopy (AFM) imaging was employed to determine morphology and roughness information of dry spin-cast chitosan films.     

Extended Conjugation in Polyaniline Like Structure Prepared by Plasma Polymerization Suitable for Optoelectronic Applications

Plasma polymerization of aniline is carried out in a radiofrequency plasma reactor and the effect of polymerization time is examined in the structural, optical and optoelectronic properties of deposited films. Conjugated structures of polyaniline like films are obtained with unique and broad optical absorption band in the ultraviolet and entire visible region. The width of the absorption band increases and hence the optical band gap decreases with polymerization time. The optical constants are extracted by Swanepoel method and the optical dispersion parameters are determined by employing the Wemple-DiDomenico single oscillator model. The films exhibit similar thermal stability in air and argon atmosphere in the region of interest for optoelectronic applications. The photoluminescence study suggests, like the chemically synthesized polyaniline, the benzenoid units to be responsible for fluorescence. The fluorescence peaks due to defect states confirm the formation of spectroscopic units in the plasma polyaniline films.     

Langmuir-Blodgett films of polymethacrylates with side chains containing functionalized aromatic schiff's bases

Langmuir-Blodgett (LB) film formation has been investigated for polymers in which non-linear optical (NLO) moieties are attached to the side chain of a polymethacrylate (PMA) backbone. Polymer monolayers were successfully transferred onto hydrophilic glass substrates using a moving-wall type LB trough. The LB films were characterized by pressure-area isotherms, polarized ultraviolet visible spectra, ellipsometry, and second harmonic generation measurements. The characterization shows that NLO moieties in the side chain are inclined at a shallow angle to the plane of the substrate. The second-order nonlinear optical coefficient and molecular hyperpolarizability were also calculated. © 1993 John Wiley & Sons, Inc.     

Improved optical and electrical properties of sol–gel-derived boron-doped zinc oxide thin films

Sol–gel spin-coating was used to grow zinc oxide (ZnO) thin films doped with 0–2.5 at.% B on quartz substrates. The structural, optical, and electrical properties of the thin films were investigated using field-emission scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), ultraviolet–visible spectroscopy, and van der Pauw Hall-effect measurements. All the thin films had deposited well onto the quartz substrates and exhibited granular morphology. The average crystallite size, lattice constants, residual stress, and lengths of the bonds in the crystal lattice of the thin films were calculated from the XRD data. The PL spectra showed near-band-edge (NBE) and deep-level emissions, and B doping varied the PL properties and increased the efficiency of the NBE emission. The optical transmittance spectra for the undoped ZnO and boron-doped zinc oxide (BZO) thin films show that the optical transmittance of the BZO thin films was significantly higher than that of the undoped ZnO thin films in the visible region of the spectra and that the absorption edge of the BZO thin films was blue-shifted. In addition, doping the ZnO thin films with B significantly varied the absorption coefficient, optical band gap, Urbach energy, refractive index, extinction coefficient, single-oscillator energy, dispersion energy, average oscillator strength, average oscillator wavelength, dielectric constant, and optical conductivity of the BZO thin films. The Hall-effect data suggested that B doping also improved the electrical properties such as the carrier concentration, mobility, and resistivity of the thin films.     

Graft polymerization of epoxide and alternating graft copolymerization of epoxide–acid anhydride onto a polystyrene backbone having an aminimide moiety

Graft polymerization of glycidyl phenyl ether (GPE) and alternating graft copolymerization of GPE–succinic anhydride (SA) onto a polymer‐supported aminimide were examined. The polymer‐supported aminimide was synthesized by radical polymerization of 1,1‐dimethyl‐1‐(2‐hydroxy‐3‐(4‐vinylbenzyloxy)propyl)amine 2‐benzoylimide, which was prepared by the reaction of methyl benzoate with equimolar amounts of 1,1‐dimethyl hydrazine and 4‐glycidylmethylstyrene. This aminimide could initiate the polymerization of GPE and alternating copolymerization of GPE with SA to give the corresponding graft copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1041–1048, 1999     

Quantitative chemical composition of thin films with infrared spectroscopic ellipsometry: application to hydrated oxide films on aluminium

A method to quantify the composition of thin films using infrared spectroscopic ellipsometry (IRSE), supplemented by visible spectroscopic ellipsometry (VISSE), is proposed. Because ellipsometry measures the thickness and optical constants of a surface layer simultaneously, the absorption coefficient of the film as a function of wavelength can be obtained. Using values of the absorption coefficients for the pure components of the film, the percentages (mol.% or wt.%) of each component in the film can be calculated. The method is demonstrated in a study of the hydration of oxide films on electropolished aluminium and the anodically formed barrier oxide film. The IRSE technique shows that hydration of the films by immersion in boiling water results in the conversion of aluminium oxide to pseudoboehmite. Copyright © 2003 John Wiley & Sons, Ltd.     

Subsurface investigation of the surface modification of polydimethylsiloxane by 172‐nm vacuum ultraviolet irradiation using ToF‐SIMS and VUV spectrometry

We investigate the mechanism of polydimethylsiloxane (PDMS) surface modification by 172‐nm vacuum ultraviolet (VUV) light. Time‐of‐flight secondary ion mass spectrometry and optical spectrometry are used to measure the chemical composition and VUV transmittance of the PDMS before and after surface modification, respectively. For modified samples of bulk PDMS, the VUV transmittance and the depth of the modified region increased with increasing VUV dose. This can be explained by the following self‐reinforcing cycle of (1) modification of PDMS by VUV light to a more silica‐like composition, (2) improvement of the VUV light transparency, and (3) deeper modification. For thin‐film samples of PDMS formed on sapphire substrates, the transmittance at 172 nm also increased with increasing VUV dose and exceeded that of sapphire in the region from 172 to 300 nm. Finally, thin‐film samples of PDMS formed on silicon substrates, which function as a VUV reflector, were also investigated. For these samples, the secondary ion depth profiles for several chemical species in the PDMS were oscillatory, probably due to the interference of the incident and reflected VUV light. These results strongly suggest that the photon energy of the VUV light plays an important role in modifying PDMS.     

新型全色发光材料NaCaPO_4:Dy~(3+)制备及发光性能

釆用高温固相法制备了NaCaPO4∶Dy3+系列样品,并在紫外(UV)及真空紫外(VUV)区域研究了系列样品的发光性能.紫外激发光谱显示在350nm处有最强的激发峰,可以有效地吸收紫外光并将其转化为可见光.真空紫外激发光谱表明,NaCaPO4∶Dy3+能有效地吸收无汞荧光灯的激发源并将其转化为可见光.系列样品发光均呈现为白色,这种材料有潜力作为全色显示材料应用于发光二极管(LED)和无汞荧光灯中.     

新型全色发光材料NaCaPO4∶Dy3+制备及发光性能

釆用高温固相法制备了NaCaPO4∶Dy3+系列样品, 并在紫外(UV)及真空紫外(VUV)区域研究了系列样品的发光性能. 紫外激发光谱显示在350 nm处有最强的激发峰, 可以有效地吸收紫外光并将其转化为可见光. 真空紫外激发光谱表明, NaCaPO4∶Dy3+能有效地吸收无汞荧光灯的激发源并将其转化为可见光. 系列样品发光均呈现为白色, 这种材料有潜力作为全色显示材料应用于发光二极管(LED)和无汞荧光灯中.     

Determination of optical constants of sol‐gel derived Zn0.9Mg0.1O films by spectroscopic ellipsometry with various models

The Zn_0.9Mg_0.1O thin films were prepared on Si (100) substrates by the sol‐gel method. The structural and the optical properties of Zn_0.9Mg_0.1O thin films, submitted to an annealing treatment in the 400–700 °C ranges, are studied by X‐ray diffraction (XRD) and ultraviolet (UV)‐visible spectroscopic ellipsometry (SE). The thickness, refractive index, and extinction coefficient of these films have been determined by analyzing the SE spectra using parameterized dispersion model. Moreover, we made a detailed comparison among various dispersion models and found that the Sellmeier model was superior to others in fitting the ellipsometric spectra in the transparent region. In the interband transition region, point‐by‐point fit was used. The spectral dependence of the refractive index and extinction coefficient was obtained in the photon energy range of 1.5–4.71 eV. The influence of annealing temperature on the refractive index, the extinction coefficient, and the optical bandgap energy was also discussed. We found that the refractive index and the extinction coefficient increase with increasing the annealing temperature, meaning the optical quality of Zn_0.9Mg_0.1O films is improved by annealing. Copyright © 2009 John Wiley & Sons, Ltd.     

射流冷却的OCS分子高分辨VUV吸收光谱研究

The absorption spectrum of OCS molecules under jet-cooled conditions has been measured between 64150 and 65840 cm-1 with a highly resolved tunable vacuum ultraviolet (VUV) laser (about 0.2 cm-1), generated by two-photon resonant four wave mixing process. During the experiment, the VUV intensities prior and posterior to the OCS absorption were monitored simultaneously in order to increase the sensitivity of absorption measurement, and the absorption sensitivity △I/I was determined to be 1%. The measured spectrum is essentially similar to the S(1S) photofragment excitation spectrum under similar conditions, indicating that the dissociation to produce S(1S) fragment is the main pathway. The difference between these kinds of spectra, however, implies the existence of other dissociation channels in addition to the S(1S) pathway.     

Quantitative characterization of the optical properties of absorbing polymer films: Comparative investigation of the internal reflection intensity analysis method

Nondestructive, three‐dimensional refractive‐index measurements are used for the determination of both the crystallinity and orientation in thin polymer films. The prism wave‐guide coupler is particularly suited for three‐dimensional isotropic and anisotropic thin‐film studies because of the quantitative character of the information obtained and the ease of data acquisition. It has been limited, however, to determining only the refractive index of transparent or weakly absorbing thin‐film samples. On the basis of thin‐film optics, this study develops a new internal reflection intensity analysis (IRIA) method, which uses the intensity information rather than the conventional mode angle values to acquire both the refractive index and the extinction coefficient over a range of transparent to highly absorbing polymer films. Therefore, the IRIA method overcomes the limitations of this prism wave‐guide coupler technique, which can only measure the refractive index of a weakly absorbing sample. With a Metricon PC‐2010 as the skeletal framework, a prototype instrument has been developed to apply and test the IRIA method. A study comparing both the refractive index and extinction coefficient obtained with ellipsometry, ultraviolet–visible/near‐infrared reflectometry, and IRIA for solvent blue 59 dyed polystyrene films confirms that the IRIA method is effective for obtaining the three‐dimensional refractive indices and extinction coefficients of polymer films. In addition, the refractive index and extinction coefficient spectrum (400–800 nm) of solvent blue 59 have been determined with the effective media theory. Furthermore, the three‐dimensional complex refractive indices of highly absorbing black electrical tape, inaccessible to other optical measurement because of its surface character, has been determined by the IRIA method. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 842–855, 2003     

Silica aerogel–poly(ethylene‐co‐vinyl acetate) composite for transparent heat retention films

Poly(ethylene‐co‐vinyl acetate) (EVA) plastic films are widely used for solar coverings including photovoltaic modules and commercial greenhouse films, but are poor at controlling heat flow. In this work, silica aerogel (SA) nanogels were examined for preparing transparent heat retention EVA films that block far infrared spectra radiation to maintain heat, without compromising the optical performance of the films. SA nanogels were melt‐mixed using a mini twin‐screw extruder with EVA pellets to form SA/EVA composite, which were pressed into thin films with controlled thickness. The composite films were characterized in terms of optical properties using a variety of analytical methods including FTIR, UV–Vis spectroscopy, electron, confocal, and atomic force microscopy. Both thermicity and thermal conductivity of commercial and experimental SA/EVA films were measured. The results demonstrated that the SA/EVA films gave improved infrared retention compared to commercial thermal plastic films without compromising visible light transmission, showing the potential for this approach in next generation heat retention films. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 927–935     

Photo-impulsive reactions in the electronic ground state without electronic excitation: non-photo, non-thermal chemical reactions

Allyl phenyl ether has an absorption band in the ultraviolet region (λ < 400 nm); therefore, irradiation with few-optical-cycle ultraviolet pulses (λ = 360-440 nm) causes a transition to the ultraviolet band, which leads to an electronic state and a photo-Claisen rearrangement (radical reaction) in the electronic excited state. However, the reaction scheme of allyl phenyl ether under irradiation with few-optical-cycle visible pulses (λ = 525-725 nm) was determined to be same as that of the thermal Claisen rearrangement ([3,3]-sigmatropic rearrangement), which is symmetry-allowed in the electronic ground state. Photo-excitation with few-optical cycle visible pulses below the absorption band induces a photo-impulsive reaction in the electronic ground state without electronic excitation, of which the trigger scheme is different from that of photoreaction or thermal-reaction. The photo-impulsive reaction in the electronic ground state is highly possible as a novel reaction scheme.     

Hydrogen bonding in liquid water probed by resonant Auger-electron spectroscopy

We have measured resonant and off-resonant Auger-electron spectra of liquid water. Continuumlike transitions near and above the O1s vertical ionization energy are identified by the characteristic normal Auger-electron spectra. On the contrary, well-resolved spectator shifts of the main Auger-electron peak are observed at the liquid-water O1s absorption main edge and near the absorption pre-edge. The shifts of 1.4 and 1.9 eV arise from the localized nature of the excitation. Excited-state localization/delocalization is also discussed for the analogous vacuum ultraviolet (VUV) transitions, and we point out the similarities between x-ray and VUV absorption spectra of liquid water.     

New liquid‐crystal alignment agents based on fluorinated polyimides with trifluoromethyl‐substituted benzene or diphenylether in the side chain

Fluorinated copolyimides derived from 4,4′‐oxydiphthalic anhydride (ODPA) with 4,4′‐oxydianline (ODA) and trifluoromethyl‐containing aromatic diamines have been synthesized and characterized. The trifluoromethyl‐containing diamines include 2,4‐diamino‐3′‐trifluoromethylazobenzene, 2,4‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] aniline, 3,5‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] benzamide, 3,5‐diamino‐1‐[(3′‐trifluoromethyl) phenyl] benzamide, 1,4‐bis(4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl) benzene, 3,5‐diaminobenzenetrifluoride, 4,4′‐diamino‐4″‐(p‐trifluoromethyl phenoxy) triphenylamine, and 4‐[(4′‐trifluoromethylphenoxy) phenyl]‐2,6‐bis(4″‐aminophenyl)pyridine. Strong and flexible copolyimide films, produced by casting the polyamic acid solution followed by thermal imidization, exhibited great thermal stability and high mechanical properties. The polyimides had an ultraviolet–visible absorption cutoff at 330–340 nm and pretilt angles as high as 20° for nematic liquid crystals, making them great potential candidates for advanced liquid‐crystal display applications. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1583–1593, 2002     

Evaluation of piezoelectric PVDF polymers for use in space environments. II. Effects of atomic oxygen and vacuum UV exposure

The effects of atomic oxygen (AO) and vacuum UV radiation simulating low Earth orbit conditions on two commercially available piezoelectric polymer films, poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE), have been studied. Surface erosion and pattern development are significant for both polymers. Erosion yields were determined as 2.8 × 10^?24 cm³/atom for PVDF and 2.5 × 10^?24 cm³/atom for P(VDF‐TrFE). The piezoelectric properties of the residual material of both polymers were largely unchanged after exposure, although a slight shift in the Curie transition of the P(VDF‐TrFE) was observed. A lightly cross‐linked network was formed in the copolymer presumably because of penetrating vacuum ultraviolet (VUV) radiation, while the homopolymer remained uncross‐linked. These differences were attributed to varying degrees of crystallinity and potentially greater absorption, and hence damage, of VUV radiation in P(VDF‐TrFE) compared with PVDF. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2503–2513, 2005     

Effects of In, Al and Sn dopants on the structural and optical properties of ZnO thin films

Effect of In, Al and Sn dopants on the optical and structural properties of ZnO thin films have been investigated by X-ray diffraction technique and optical characterization method. X-ray diffraction patterns confirm that the films have polycrystalline nature. The thin films have (002) as the preferred orientation. This (002) preferred orientation is due to the minimal surface energy which the hexagonal structure, c-plane to the ZnO crystallites, corresponds to the densest packed plane. The grain size values of the films are found to be 29.0, 35.2 and 39.5 nm for In, Al and Sn doped ZnO thin films, respectively. The optical band gaps of the films were calculated. The absorption edge shifts to the lower wavelengths with In, Al and Sn dopants. The inclusion of dopant into films expands also width of localized states as E(UIn)>E(UAl)>E(USn). The refractive index dispersion curves obey the single oscillator model. The dispersion parameters and optical constants of the films were determined. These parameters changed with In, Al and Sn dopants.