Vibrational spectroscopy advantage

Taking into consideration that antenna xanthophylls not only possess original absorption but also resonance Raman spectra, and the fact that the Raman signal is virtually free from vibrational spectroscopy artifacts (water, sample condition, etc.), it seemed of obvious advantage to apply the described combination of spectroscopies for the identification of these pigments. 

As this chapter aims at explaining the basics, operational principles, advantages and pitfalls of vibrational spectroscopic sensors, some topics have been simplified or omitted altogether, especially when involving abstract theoretical or complex mathematical models. The same applies to methods having no direct impact on sensor applications. For a deeper introduction into theory, instrumentation and related experimental methods, comprehensive surveys can be found in any good textbook on vibrational spectroscopy or instrumental analytical chemistry1"4. 

Inelastic electron tunneling spectroscopy (lETS) takes advantage of the general applicability of vibrational spectroscopy by measuring the vibrational spectrum of molecules adsorbed on the insulation of a metal-insulator-metal junction (Figure 1). 

Dielectric spectroscopy, also known as impedance spectroscopy, has been used for process analysis for some time, as it offers the ability to measure bulk physical properties of materials. It is advantageous to other spectroscopic techniques in that it is not an optical spectroscopy and is a noncontact technique, allowing for measurement without disturbing a sample or process. The penetration depth of dielectric spectroscopy can be adjusted by changing the separation between the sensor electrodes, enabling measurement through other materials to reach the substrate of interest. Because it measures the dielectric properties of materials, it can provide information not attainable from vibrational spectroscopy. 

One of the great advantages of vibrational spectroscopy is that many hydrocarbon groupings, such as CH3, CH2, C=C, C=C, etc., have characteristic vibration frequencies/wavenumbers, many of which fall in the wavenumber ranges transmitted by oxide supports. Furthermore, for use in connection with... 

NMR is a widely used and important technique for molecular structure determination as applied to bulk materials, where it competes, often advantageously, with vibrational spectroscopy. However, a lack of sensitivity has limited its application to the study of adsorption on high-area finely divided surfaces. Also, certain metals with bulk magnetic properties—e.g., Fe, Co, and Ni (but not the other group Vlll transition metals)—cannot be studied by the technique as their magnetism causes very broad and weak resonances from adsorbed species. 

The purpose of this chapter is to demonstrate the usefulness of vibrational spectroscopy [1-8] and atomic force microscopy (AFM) [9,10] in the studies of monolayers on air/solid interfaces. In this chapter, considerable attention is paid to the combined use of vibrational spectroscopy and AFM. These two techniques, widely used in the studies of monolayers on air/solid interfaces, have complementary advantages vibrational spectroscopy is suitable to investigate structure and orientation of monolayers [2,3,6-9], while AFM is useful to observe the surface morphology and the thickness of the monolayers [9]. 

Application of dispersive spectrometers and interferometers to vibrational spectroscopy the Jacquinot advantage... 

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