Surface plasma excitation

J. Derov Y.Y. Teng and A.S. Karakashian, Angular Scan Spectrum of a Surface Plasma Excitation on a Schottky Diode , Phys. Lett. A, 95 (1983) 197. 

In this Section we want to present one of the fingerprints of noble-metal cluster formation, that is the development of a well-defined absorption band in the visible or near UV spectrum which is called the surface plasma resonance (SPR) absorption. SPR is typical of s-type metals like noble and alkali metals and it is due to a collective excitation of the delocalized conduction electrons confined within the cluster volume [15]. The theory developed by G. Mie in 1908 [22], for spherical non-interacting nanoparticles of radius R embedded in a non-absorbing medium with dielectric constant s i (i.e. with a refractive index n = Sm ) gives the extinction cross-section a(o),R) in the dipolar approximation as ... 

The surface modification of polymers for improvement of adhesive bonding, and altering surface properties in general without concomitant modification of bulk properties is an active area of research in both industrial and academic laboratories and has been accomplished by a variety of means ranging from Corona discharge treatment, direct chemical modification and by interaction with plasmas excited in inert gases either capacitively or inductively27. ... 

One simple explanation for these results was as follows The electric field at a metal vacuum interface can be >10 times larger than in free space when the conditions required for a surface plasma resonance are met (47). Since the Raman cross-section is proportional to the square of the field, surface plasmons could produce enhancements of >10. This enhancement is probably not large enough to explain the tunneling junction results by itself, but an enhancement in signal of a factor of 100 by the excitation of surface plasmons would increase the Raman intensity from near the limits of detectibility. 

There are reports [24,25] that it is possible to decrease the MOVPE growth temperature to 550°C by using the nitridated surface of sapphire without the subsequent buffer layer. Tokuda et al [24] reported the GaN 00.2 FWHM dependence on the nitridation time of sapphire at 940°C in a plasma-excited N2 atmosphere. Using this technique, the best MOVPE GaN layers of FWHM less than 20 arc min were grown on a surface nitridated for 10 - 20 min. In a similar experiment, Kim et al [25] obtained GaN of the best 00.2 FWHM of 0.4 degrees for 10 min nitridation time. 

The metallic nanocrystals are remarkable due to their localized surface plasmon resonance (SPR) phenomenon, that is, the excitation of surface plasma by light. It ensures these nanocrystals to be color based sensors (Homola et al., 1999 Kelly et al., 2003). The metallic nanocrystals could also sensitize the Raman signals from their adsorbed organic molecules. This surface enhanced Raman scattering (SERS) effect potentially raises the detection sensitivity to single molecule level (Kneipp et al., 1997 Nie and Emery, 1997). 

The first feature that chemically reactive species are created by the interaction of molecules (in gas phase or on the surface) with excited neutral species of Ar has a very significant influence in the surface modification of polymers. When a polymer surface is exposed to Ar or O2 plasma, the energetic ions and electrons (at the level of ionization energy) bombard the surface. The influence on the surface is determined by the energy level. The chemical bonds involved in the molecules that constitute the surface are relatively low (3 eV) compared to the ionization energy of the gas used in plasma (over lOeV). 

Otto, A. (1968). Excitation of nonradiative surface plasma waves in silver by the method of fimstrated total reflection. Zeitschrift fur Physik 216 398-410. 

Otto, A. (1968) Excitation of Nonradiative Surface Plasma Waves in Silver by Method of Frustrated Total Reflection. Zeitschrift fur Physikalische 216 398-410. 

DeMarco DV, Lim DV (2001) Direct detection of escherichia coliol57 h7 in unpasterized apple juice with an evanescent wave sensor. J Rapid Meth Automation Micro 9 241-257 Diez A, Andres MV, Cruz JL (2001) In-line fiber-optic sensors based on the excitation of surface plasma modes in metal-coated tapered fibers. Sensors Actuators B Chem 73 95-99 Dostalek J, Ctyroky J, Homola J, Brynda E, Skalsky M, Nekvindova P, Spirkova J, Skvor J, Schrofel J (2001) Surface plasmon resonance biosensor based on integrated optical waveguide. Sensors Actuators B Chem 76 8-12... 

In a metal, the superposition of many electron-hole pairs leads to a wave-like disturbance of the charge density at the surface. This disturbance is called the surface plasmon. Its frequency is related to the bulk plasma frequency co/, as co, = oj/,/V2. The existence of both surface and bulk plasma excitation was detected under conditions of electron-beam or photon excitation, and their corresponding energies are in the range of 5-20 eV (8-32 x 10 J). 

An optical transduction method that is often used with ultrathin hlms, such as LB hlms, is that of surface plasmon resonance [30, 31]. Surface plasma waves are collective oscillations of the free electrons at the boundary of a metal and a dielectric. These can be excited by means of evanescent electromagnetic waves. This excitation is associated with a minimum in the intensity of the radiation reflected from the thin him system, called surface plasmon resonance (SPR). The sensitivity of SPR is noteworthy, and changes in refractive index of 10 may be monitored thus the technique compares favorably with ellipsometry. The method has been used with LB hlms to provide both gas detectors [29] and sensors for metal ions in solution [32]. 

Gasification stimulated by non-thermal plasma excitation and subsequent dissociation of H2 was also observed in experiments with production of hydrides of sulfur, arsenic, germanium, tin, tellurium, and selenium (Bonhoeffer, 1924 Pearson, Robinson, Stoddart, 1933 Radford, 1964). The mechanism of hydride production includes in this case volume and surface dissociation of excited hydrogen molecules, chemisorption of atomic... 

Chemisorption of plasma-excited CO molecules on a chromium surface ... 

Otto A., A new method for excitating nonradiactive surface plasma oscillations, Phys. Stat. Sol, 26, K99-K101, 1968. 

Another area of growing importance in optical sensing is the surface plasmon resonance (SPR). This technique makes use of the surface plasma wave (SPW) that may exist at the interface of two media with dielectric constants of opposite signs, e.g., a metal and a dielectric. The excitation of the SPW by... 

The layout of a commercial apparatus for electron gas SNMS is depicted in Figure 2. The sample head is introduced directly into the postionizing electron gas. Particle emission from the sample surface is excited by extracting ions from the ECWR plasma by a simple ion optical arrangement in front of the sample (direct bombardment mode, DBM). Since the angular distribution of sputtered particles changes from a torus-like configuration to an over-cosine behavior when the... 

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