Surface Electromagnetic Wave Spectroscopy Research Articles

Qualitative Analysis of Nanogram Samples with Fourier Transform Infrared Transmission Surface Electromagnetic Wave Spectroscopy

The intensity enhancement of infrared spectra with Ag island films in surface electromagnetic wave spectroscopy (SEWS), which is commonly associated with the ATR method, was observed with the use of an ordinary transmission configuration. We refer to this as “transmission SEWS” or “T-SEWS.” With 10 nm Ag, the magnitude of enhancement factor was about 200 for the NO2 symmetric stretching band at 1350 cm−1 with p-nitrobenzoic acid. In order to estimate its effectiveness as a qualitative analytical method, T-SEWS spectra were compared with normal transmission spectra with the use of several samples. The results showed that T-SEWS is useful in detecting and identifying nanogram amounts of substances which do not have reactive functional groups—e.g., triphenyl phosphate (TPP) or polydimethylsiloxane (PDMS), which do not have -COOH, -SO3H, -C=S, etc. A usable spectrum was observed from as little as 25 ng/cm2 of TPP with the use of a standard triglycine sulfate detector without a beam condenser. Combined with microspectroscopy, T-SEWS shows promise for picogram order analysis and chromatographic applications.

IR-RA and SEW spectrokinetic study of surface stages of heterogenious Catalytic reactions: oxygen, water and methane interaction with the surface of Al 2O 3, BaO, CaO thin films

The IR Reflection-Absorption Spectroscopy and Surface Electromagnetic Wave (SEW) Spectroscopy are described as methods for Investigation of adsorption and catalysis on non-metal thin films deposited on flat metal surfaces. Study of oxygen, water and methane Interaction with Al, Ca and Ba oxides shows that spectrokinetic and mechanistic information can be obtained from SEW spectroscopy data.

Fourier transform ir reflection techniques for characterization of polyimide films on copper substrates

The interaction of polyimide and copper at elevated temperatures is poorly understood, despite the fact that this system is of great importance for various microelectronic devices. In this study, we have used Fourier transform IR spectroscopy to study the copper-catalyzed degradation of polyimide and its precursor, polyamic acid. We have examined this system in both air and nitrogen and with both copper and chromium as test substrates. Also discussed in this paper is the application of two new spectroscopy techniques: surface electromagnetic wave spectroscopy and grazing-angle-incident metal overlayer attenuated total reflection spectroscopy. The increased sensitivity offered by these techniques is far and above that of traditional reflection-absorption spectroscopy. We are also able to study the different interfaces that exist between the copper and the polyimide with the metal overlayer technique. The combined use of all three experimental methods allows us to examine the interfacial regions of the polyimide/copper system fully.

Infrared study of hydrogen chemisorbed on W (100) by surface electromagnetic wave spectroscopy

The inhibition of the structure c(2x2)H or c(2x2)D reconstruction in the case of H or D chemisorption on the surface W(100) is observed by surface electromagnetic wave spectroscopy. The strong band at 960 cm−1 is referred to overtone of wagging mode.

Surface-reconstruction-induced changes in free-carrier scattering from the W(100) surface: An infrared surface-electromagnetic-wave study.

Using the infrared-absorption technique of surface-electromagnetic-wave spectroscopy (SEWS) we have studied the effects of H/sub 2/ and D/sub 2/ chemisorption on the SEW attenuation coefficient ..cap alpha.. in the 10-..mu..m region between 165 and 350 K. The change in ..cap alpha.. at room temperature has also been measured for N/sub 2/, O/sub 2/, and CO adsorption. The coverage (C-italicT-italicH-italicE-italicT-italicA-italic) dependence of ..cap alpha.. for N/sub 2/, O/sub 2/, and CO is fairly simple (either a monotonic increase (N/sub 2/) or a peak at some intermediate coverage (O/sub 2/, CO)) and points to changes in free-carrier (FC) surface scattering as the dominant ..cap alpha..-changing mechanism. Much richer structure in ..cap alpha..(C-italicT-italicH-italicE-italicT-italicA-italic) upon H/sub 2/ and D/sub 2/ adsorption is observed: A small peak followed by a sharp dip at C-italicT-italicH-italicE-italicT-italicA-italic = 0.42 monolayer (ML) (C-italicT-italicH-italicE-italicT-italicA-italic = 2 monolayers equivalentsaturation), a broad maximum at C-italicT-italicH-italicE-italicT-italicA-italic = 1.28 ML, and a value at C-italicT-italicH-italicE-italicT-italicA-italic = 2.0 ML higher than for the clean surface. For C-italicT-italicH-italicE-italicT-italicA-italic>0.42 ML the variations are dominated by reconstruction-induced changes in FC scattering from the surface.

FT-IR surface electromagnetic waves (SEW) absorption spectroscopy of very thin films on metals

Two methods are compared experimentally and theoretically: surface electromagnetic wave spectroscopy (SEWS) and infrared reflection-absorption spectroscopy (IRAS) at the angle of incidence 88°. On the example of the 4-n-octadecylphenol Langmuir films on copper it was shown that the sensitivity of SEWS is about one order greater than that of IRAS, the ratio of sensitivities growing with the increase of the film thickness. A Fourier-spectrometer for broad band IR spectra measurements was used.

High-Resolution Infrared Study of Hydrogen (1×1) on Tungsten (100)

The first high-resolution observation of the ${\ensuremath{\nu}}_{1}$ vibrational mode of H chemisorbed on W(100) at saturation coverage has been obtained by surface electromagnetic wave spectroscopy.

3867. ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy. (USA)

3867. ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy. (USA)

Ir study of molecules adsorbed on metal surfaces by surface electromagnetic wave spectroscopy

The infrared spectra of monolayer coverages of two different molecules (KReO4 and SF6) physisorbed on metal surfaces have been measured in the 10-μm region by means of a new surface electromagnetic wave (SEW) coupling technique in conjunction with a CO2 laser. Coverages as low as two monolayers can be readily monitored in agreement with predictions based on an optical sum rule. The new coupling configuration is based on the principle of inhomogeneous wave coupling and allows the matching of both the propagation wave vector and the spatial profile of the SEW. Our method is both more efficient and more convenient for SEW spectroscopy than the conventional prism technique.

Absorption in the infrared of surface electromagnetic waves by adsorbed molecules on a copper surface

Experimental observations have been made for the first time that surface electromagnetic wave (SEW) spectroscopy can be used to measure the infrared spectra of adsorbed molecules and very thin films on metal surfaces. Using a tunable CO2 laser (9.2–10.8 μm wavelength), the 975 and the 1037 cm−1 resonances of 5–25 Å thick physisorbed benzene on copper were observed. Broadening of these resonances for the thinnest layers of benzene was observed. Also SEW spectroscopy and ellipsometry were used to study thin films of cellulose acetate (15–75 Å) on copper. Further, it was shown that film thicknesses determined by SEW spectroscopy are in agreement with the ellipsometric thicknesses and that the SEW method is more sensitive for very thin (<25 Å) films.