Surface properties, radiofrequency

Chemically modified celluloses have been analyzed by conventional wet methods and by various Instrumental methods designed to differentiate bulk and surface properties. Electron emission spectroscopy for chemical analyses (ESCA) used alone and In combination with radiofrequency cold plasmas yielded elemental analyses, oxidative states of the element, and distribution of the element. Techniques of electron paramagnetic resonance (EPR), chemiluminescence, reflectance infrared spectroscopy, electron microscopy, and energy dispersive X-ray analyses were also used to detect species on surfaces and to obtain depth profiles of a given reagent in chemically modified cottons. 

There are other important properties tliat can be measured from microwave and radiofrequency spectra of complexes. In particular, tire dipole moments and nuclear quadmpole coupling constants of complexes may contain useful infonnation on tire stmcture or potential energy surface. This is most easily seen in tire case of tire dipole moment. The dipole moment of tire complex is a vector, which may have components along all tire principal inertial axes. 

This chapter aims to discuss and summarize theoretical and practical aspects of such plasma interfaces, presenting the existing examples from our own recent work on plasma electrochemical reactions between typical ionic liquids and plasmas. First, we address the plasma state and essential properties with respect to its application in electrochemistry. Today, low temperature plasmas - mostly in the form of radiofrequency or microwave plasmas - play an important role in the treatment or modification of solid surfaces. However, as plasma chemistry is usually not an element of chemistry curricula, we include a very brief introduction but refer the reader to the literature for more detailed information. 

Several deposition techniques have been investigated such as laser ablation, pulsed laser deposition, electrostatic spray and sputtering [127]. Orlovskaya and co-workers utilised Raman spectroscopy in conjunction with SEM, XRD, and energy dispersive X-ray analysis to study the structural properties of a 200 nm thick LaCrOa protective thin film deposited on high temperature steels by radiofrequency magnetron sputtering [126]. Fig. 12(a) shows the Raman spectrum of the polished stainless steel surface... 

It should be noted that a hybrid approach to design gas-sensing devices on plastic substrates can be used as well. In particular, a surface acoustic wave (SAW) chip, which require substrates with very different properties, can be transferred onto a plastic substrate Cobianu et al. (2007). Another interesting and new approach is the coating of passive (no power source on board) conventional RFID (radiofrequency identification) tags with chemically sensitive films to form a chemical sensor (Potyrailo and Morris 2007). The detection of several vapors of industrial, health, law enforcement, and security... 

Among the different types of pretreatment methods proposed, plasma treatment represents probably the most versatile and efficient method for surface modification. The properties of plasma-modified surfaces mainly depend on parameters controlled by the reaction conditions (i.e., type of gas, pressure, radiofrequency, effective power, and time of treatment) and by the physicochemical properties of the polymer used. By using short plasma treatments, the surface modification can be confined to the first atomic layers of the polymer surface. Moreover, plasma treatment offers the ability to choose the nature of the chemical modification as a function of the gas used. As an example, the introduction of amine functionalities on PHB surfaces has been achieved using ammonia plasma [47, 51]. However, the number of functional groups formed at the surface is difficult to control. 

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