Figure 1 shows an SEM image of a Ni-filled PS sample with deposits of approximately 100 nm in size. Details of the fabrication process

of the PS/Ni nanocomposite can be found in an earlier publication [15]. The light-dark transient SPV was ABT-263 nmr employed using a broad-spectrum incident white light, which included super-bandgap wavelengths. The surface was first allowed AZD2014 to saturate in light, and then to reach equilibrium in the dark. SPV signal was monitored using the Kelvin probe method, a non-contact technique utilized to measure contact potential difference (CPD) between the sample surface and the probe [8]. Characterization of a bare PS and a Ni-filled PS using SPV transients for different environments were performed in high vacuum as well as in O2, N2 and Ar. Figure 1 SEM image of a Ni-filled PS sample. SEM image (formed by back-scattered electrons) of a Ni-filled PS sample with a high density of Ni-particles in the pores with an average size of 100 nm.

Results and discussion SPV transients for both types of samples in different gases show anomalous spikes of SPV during both ‘light-on’ and ‘light-off’ events (Figure 2). Similar behavior is observed for all three gaseous environments. After obtaining the SPV transients in these gas ambients, the experimental chamber was evacuated and then the SPV transients were obtained in vacuum. As a result, we observed that the PS surface was very sensitive to the experimental ambient, as one can see from Figure 3. In vacuum, the sharp SPV spikes disappeared whereas Foretinib in vitro the light-on and light-off saturation

times became dissimilar. Resolving the SPV transients obtained in gaseous environments on the logarithmic time scale (cf. Figure 4), one can see that these curves contain both fast and slow components with opposite contributions to charge dynamics. The initial fast process in the case of light-on and light-off events in the gaseous environments occurs over a time scale of tens of seconds, whereas the entire event until saturation is in the range of thousands of seconds. However, the transients observed in vacuum revealed only one relatively fast process. Since the fast see more process is always present regardless of the ambient conditions, we believe that it is related to the charge recombination occurring in PS. On the other hand, the slow process is present only in the gaseous environments suggesting that it might be related to the non-vacuum ambient. Figure 2 SPV transients in gaseous environments. (a) Bare PS in N2. (b) Ni-filled PS in O2. Figure 3 SPV transients in vacuum. (a) Bare PS. (b) Ni-filled PS. Figure 4 SPV transients in different gas environments for Ni-filled PS on a logarithmic time scale. (a) ‘Light-on’ transient. (b) ‘Light-off’ transient. A detailed discussion of fast and slow SPV transients can be found in ref. [9]. Coexisting slow and fast charge transfer processes were reported for wide-bandgap materials and analyzed theoretically by Reschikov et al.