N2 plasma

Fig. 1. UV-Vis absorption spectra of H2+N2 plasma and O2 plasma treated Ti02 films Table 1. The optimum treatment conditions of various plasmas ...

Fig. 4. Ti2p ESCA spectra of untreated (left) and H2+N2 plasma treated TiOa films...

To enhance the formation of Ti species by reduction and nitration together, treatment with H2+N2 plasma and H2+Ar/N2+Ar (H2+Ar treatment followed by N2+Ar) were tried. However, there was no further improvement. H2+Ar/N2+Ar plasma treatment reduced the optimum treatment time to 20 minutes but improvement of photocatalytic activity imder fluorescent light was just 2.0 times. H2+Ar pretreatment seems to make substitutional doping of N easier through reduction reaction. 

Turner and Hopkins [90] previously reported an unusual structure of the EEDF. They found a dip at eV in the EEDF of a N2 plasma. They interpreted the dip as the electric absorption of a N2 molecule corresponding to the resonant peak of the vibrational excitation cross section. 

A typical OES spectrum taken from CH4-N2 plasma used in a-C(N) H film deposition is shown in Figure 13 [63]. This figure also shows band assignment of the... 

FIG. 20. Comparison of the two species model deposition rate as a function of N content, including the blocking of surface sites, with experimental results obtained from CH4/N2 plasmas. (Reproduced from [74].)... 

For longer treatment times (> 0.7 s) it has been shown (2) with the help of complementary surface techniques such as ISS (outermost layer sensitivity), Static SIMS (0.1-1 nm of information depth) and XPS (5 nm information depth), that the topmost surface layer is highly oxidized and that further chemical modifications occur beneath. The incorporation of both nitrogen and oxygen after a N2 plasma treatment have been evidenced by XPS whereas ISS did not reveal any trace of nitrogen (2). 

Previous static SIMS analyses have also shown (2) that the plasma treatment may induce fragmentation of the polymer backbone and some homogeneization of the polypropylene surface composition. Figure 6a shows static SIMS spectra obtained on a virgin polypropylene sample and Figure 6b on polypropylene which was treated in a N2 plasma for 7 seconds. 

Capitelli et al. (16) investigated the decomposition of 60-/xm AI2O3 in argon-N2 plasmas further, using the same experimental and analytical techniques as did Borgianni et al. They observed a decrease in yield... 

Figure 6.4 (a) ESR spectrum of radicals formed by exposure of a glass tube to N2 plasma at an initial N2 pressure of 12iamHg, SOW power, for 5min with subsequent exposure of the tube to air. (b) Background from untreated glass tube. Relative ordinate scale 1 1. 

The fluid mechanical aspect of luminous gas is also evident with non-polymer-forming plasma. It has been observed that the degradation of polymer exposed to N2 plasma is very severe in the constricted portion a polyethylene film inserted in the constricted portion suffered permanent deformation due to partial melting, whereas polyethylene films placed in wider portions of the tube (before and after the constriction) did not show any visible difference after they were exposed to N2 glow discharge simultaneously as depicted in Figure 20.27. 

Figure 31.2 Mg 2p spectra from depth profiles showing Mg migration into the oxide layer due to heating during extended plasma pretreatments the three samples are a) the native acetone cleaned surface, b) alkaline cleaned and deoxidized, and c) alkaline cleaned and deoxidized followed by 10 min of Ar + H2 plasma treatment and 10 min of N2 plasma treatment prior to deposition of a plasma polymer from TMS + N2, the arrow indicates the evolution as a function of sputtering time, but spacing between spectra is not linear but rather a spectral index, the lines mark the different regions on the samples, as obtained from spectra of the other constituent elements.

The significant differences between the cross sections for the electron collisions in the Ne and N2 plasmas in terms of their intensity and the energy region of their occurrence can be clearly seen from Fig. 1. These differences are the main reason for the very different kinetic properties of the electrons in the two plasmas, which will be illustrated in the following discussion for both steady-state plasmas. 

Polymer He plasma, eteh rate g/(em h) N2 plasma, etch rate g/(em h) O2 plasma, etch rate g/(cm h)... 

The type and density of surface states of NS-Ti02 are affected by the synthesis process. For instance, a soft mechanical treatment of TiOi nanopowder was found to reduce its photocatalytic activity in the reduction of Cr(VI) [61]. On the other hand, treatment in either H2 or N2 plasma was found to enhance the activity within the visible-light range for certain reactions [62]. The interplay between processing conditions and photocatalytic activity remains largely a state-of-the-art and is beyond prediction at this point. Ti02 has typically been calcined or... 

The post-grafting reaction provides a strong and irreversible adhesion between the grafted layer and the substrate, since a covalent bond is estabhshed. We grafted N-vinylpyrrolidone (NVP) monomer onto a polypropylene (PP) surface pretreated with cold N2 plasma (Scheme 12.1). After the plasma treatment, the modified surface was dipped in aqueous NVP solution for several periods of time (1-50 h) and at various temperatures (60-80°C). 

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