Thin film sample

For thin-film samples, abrupt changes in refractive indices at interfrees give rise to several complicated multiple reflection effects. Baselines become distorted into complex, sinusoidal, fringing patterns, and the intensities of absorption bands can be distorted by multiple reflections of the probe beam. These artifacts are difficult to model realistically and at present are probably the greatest limiters for quantitative work in thin films. Note, however, that these interferences are functions of the complex refractive index, thickness, and morphology of the layers. Thus, properly analyzed, useful information beyond that of chemical bonding potentially may be extracted from the FTIR speara. 

Perhaps conceptually one of the simplest tests for comparing the stability of related polymer samples is that of measuring oxygen uptake. In such a measurement the amount of oxygen reacting with a polymer sample, at a particular temperature and over a specific time, can be measured either manometrically or volumetrically, by a relatively simple device [1], such as that illustrated in Figure 4 [10]. Whereas such a measurement may be made on solid samples, such as sheet, powder or film, in order to minimise errors, the measurement is preferably made on thin film samples. 

Spend time on data accumulation if you plan to evaluate the data. Exposure of one WAXS curve from a modern thin-film sample that is good enough for line profile... 

Sheet resistance (Rs) is defined by p = Rst, where p is resistivity and t is film thickness. For CuGaS2 thin-film samples, Rs was determined using the four-point probe method53 and calculated from current-voltage data (Fig. 6.17) using... 

To evaluate the reactivity of model compounds III-VIII in photoinitiated cationic polymerization, we have employed real-time infrared spectroscopy (RTIR). Thin film samples of the model compounds containing 0.5 mol% of (4-n-octyloxyphenyl)phenyliodonium SbF - as a photoinitiator were irradiated in a FTIR spectrometer at a UV intensity of 20 mW/cm2. During irradiation, the decrease in the absorbance of the epoxy ether band at 860 cm-1 was monitored. 

Films for the DCC approach can be deposited by any conventional film deposition technique including CVD, evaporation, PVD, sol-gel, etc. By monitoring the rates and the deposition time for each of the constituents in a given sample, approximate compositions of the various samples can be tracked. However, in any thin-film sample the direct structural and compositional evaluation is problematic. 

EDX-SEM results measured on a thin-film sample on a carbon tape showed that the nanowires contained Si and O (Fig. 10.15). The ratio of Si to O was approximately 1.5-2 1, suggesting that the nanowires were made of Si02 with O vacancies. This also agreed with the results from the PL and Raman experiments. No carbon signal from the carbon tape was observed because the film was too thick for the e-beam to penetrate. 

For a given detector and a given pair of elements the last two factors give a single constant (Icab) that can be treated as a relative sensitivity factor. Both that factor and the method obtained their names after the two people who introduced them, Cliff and Lorimer (1975). The simplicity originates from the fact that the Uab factor does not depend either on the rest of elements also present in the sample or on the other parameters of the sample (thickness, density), as far as the thin film criterion is fulfilled. The Cliff-Lorimer factors can either be calculated using the known parameters of the detector or can be measured if a well-characterized thin film sample (standard) is available. In the first case the method is standardless. In the second case the known weight fractions and the measured intensity ratio provides the Cliff-Lorimer factor for the pair of elements. 

As an example, result from a test sample is presented in Figure 6. A nano-crystalline thin film sample was prepared by vacuum evaporation of 100 A NiO and 100 A Al. The thicknesses were controlled by quartz thickness measurement. The proportion of phases was also checked by EDS. TEM BF and DF pictures show that the grain size of NiO is around 4 nm. 

To obtain a measure of the dielectric constant and anisotropy of thin films, the refractive index of thin film samples was measured. It has been shown that the measured dielectric constant is approximately the square of the refractive index at 633 nm wavelength [the actual relationship is roughly e (refractive index) -i- 02.] and the anisotropy is obtained from the difference between the in-plane and out-of-plane refractive index [97]. The measured anisotropy of foamed polyimides is lower than that observed for non-foamed polyimides. In addition, a drop in refractive index of the samples was observed upon foaming. The polyimide PMDa/3FDA has a measured dielectric constant of ca. 2.9 at 70 °C. A foamed sample of PMDA/3FDA derived from copolymer 6f showed a drop in dielectric constant of 2.3 [97]. 

Similar photochemistry was also observed with thin-film samples, as well as porous versions of these phosphonates [41], The quantum yield for the formation of charge-separated species in the thin films was reported to be 0.15. The changes observed in the electronic absorption spectra of the samples, with time,... 

Thin film samples of these polymers give yellowish orange emission with Xmax at 534—538 nm, except for 2b ( max at 509 nm) and 2c ( max at 536 nm). The emission from a thin film sample of 2g ( max at 538 nm) shows a Stokes shift of 792 cm-1 from that of PL recorded in DMF solution. The shift is attributed to excimer formation resulting from ir-ir stacking interactions in the solid state. Polymer 2c exhibits a more greenish EL emission compared to the other polymers, probably due to the presence of the bulky /-butyl groups, which prohibits aggregation of the polymer chains and suppresses excimer formation. 

Transmission Thin film sample (little or no preparation required)... 

We would like to sincerely thank Prof. H. Funakubo of Tokyo Institute of Technology and Prof. R. Ramesh of University of Maryland for supplying the pzt thin film samples. 

Figure 1. Schematic representation of secondary x-ray production for (a) bulk sample and (b) thin-film sample.

Untreated PEUU controls (which had been exposed to GOx) exhibited no stain after continuous stirring in SDS, Triton, and sodium phosphate. GOx-PPNVP/PEUU samples washed by the same method as well as PEUU controls washed by less stringent methods exhibited positive stain. Thus the immunochemical stain assay demonstrated that the continuous wash in SDS, Triton, and sodium phosphate removed physically adsorbed GOx from the surface of GOx-PPNVP/PEUU, leaving covalently bound GOx. Positive stain was easily observable with the naked eye, making the immunochemical stain an effective novel technique for the quick screening of wash procedures for thin film samples. 

For thin film samples the analysis of the RBS spectra is generally straightforward, especially when the peaks are well separated. For bulk samples and samples with layers of different compositions the spectrum will be a complicated sum of the individual element spectra. For analysis, a model spectrum is generated based on assumptions about the elemental composition and element distribution in the sample. The model parameters are (manually or by a minimisation routine) adjusted until a satisfactory agreement with the measured spectrum is obtained. 

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