30 ± 0.05
0.30 ± 0.05 0.50 ± 0.05 After exposure Fosbretabulin ic50 in dry air 1.55 ± 0.05 3.50 ± 0.05 0.25 ± 0.05 After subsequent TDS 1.30 ± 0.05 1.10 ± 0.05 0.15 ± 0.05 At the next step of our studies, the freshly deposited Ag-covered L-CVD SnO2 nanolayers were long-term exposed (aged) in dry air atmosphere at room temperature and this caused evident changes in their surface chemistry. Firstly, the relative [O]/[Sn] concentration reached the value of 1.55 ± 0.05. Likely, the increased O concentration after air exposure is due to the surface contaminations containing oxygen (CO2, H2O), what will be discussed and analyzed later on the basis of TDS spectra. Simultaneously, the relative [Ag]/[Sn] concentration evidently (more than twice) decreased reaching value 0.25 ± 0.05. At this point, we presume that to some extent, the even distribution of Ag atoms at the surface/subsurface of SnO/SnO2 films in the form of very flat 3D (2D) nanoparticles/clusters is related to the aging effect. However, what is most important to notice is that after this
procedure, remarkable C contamination was detected, observed in the form of a strong www.selleckchem.com/products/CP-690550.html C1s XPS peak shown in the survey spectra in Figure 1. The corresponding relative [C]/[Sn] concentration was equal to 3.50 ± 0.05. This value is one order CP673451 larger than for the freshly deposited Ag-covered L-CVD SnO2 nanolayers. However, it should be pointed out at this moment that this high C contamination observed by XPS method concerns only the very thin near-surface region of the investigated films because the information depth for SnO2 is about 4 nm. Moreover, our recent depth profiling XPS experiments showed that C contamination is mostly located only at the topmost 2 to 3 atomic layers because going down
in depth, the relative concentration of [C]/[Sn] was about 0.1, TGF-beta inhibitor which was almost constant up to the Si substrate. This is strongly related to the grain-type surface morphology of Ag-covered L-CVD SnO2 nanolayers with the grains standing up in respect to the surface plane, as observed in the AFM image shown in Figure 2. Figure 2 AFM image of the Ag-covered L-CVD SnO 2 nanolayers. Very precise standard AFM depth profiling analysis (with DI software) showed that the maximum grain height and the maximum grain width for these nanolayers were estimated as equal to about 3 and 30 nm, respectively. In turn their average roughness was about 0.5 nm, which was very similar to the pure L-CVD SnO2 nanolayers, as determined in our recent AFM studies . It means that deposition of 1 ML of Ag does not significantly modify the surface/subsurface morphology of L-CVD SnO2 nanolayers.