## 3 Results and Discussion
### SEM for AuNP Samples with pH Adjusted Prior to Production  
Figure 6 shows the data obtained from SEM and EDS analyses. EDS proved the formation of AuNPs in the samples.  
The EDS results showed there were organic compounds in the samples (distinct C K\(\alpha\) peaks) due to the presence of capping agents on the surface of AuNPs. Moreover, the Si peak can be seen in the EDS results, which represents the presence of silicon from the bed of the wafer. The unwashed samples contained a high concentration of organic compounds that hide the AuNPs under a thick dried organic layer. This also caused severe sample charging problems.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline
**Vars** & **\(N\)** & **Mean** & **SD** & **Median** & **Trimmed** & **Mad** & **Min** & **Max** & **Range** & **Skew** & **Kurtosis** & **SE** \\ \hline Diameter\_Meard & 416.0 & 16.3 & 5.2 & 15.9 & 15.9 & 4.9 & 4.8 & 40.3 & 35.5 & 0.9 & 1.7 & 0.3 \\ Diameter\_Min 1 & 416.0 & 12.8 & 4.7 & 12.5 & 12.6 & 4.5 & 1.5 & 28.2 & 26.6 & 0.4 & 0.1 & 0.2 \\ Diameter\_Max 1 & 416.0 & 18.2 & 5.7 & 17.7 & 17.8 & 5.1 & 6.1 & 47.4 & 41.3 & 1.0 & 2.6 & 0.3 \\ \hline \end{tabular}
\end{table}
Table 1: Summary of descriptive statistics of the AuNPs size of the washed sample at pH 6 (the pH was adjusted prior to the preparation of the AuNPs) shown in Figures 4B and 5. The table summarizes the standard output of the R function describe see details in Mangiafico [34; 35]. Vars = number of variables in a data set; \(N\) = size of a data set; mean = arithmetic mean; SD = standard deviation; median = the mean value in a data set; trimmed = mean trimmed to 60%, 20% off each side; mad = the absolute deviation of the median; min = minimum value in a data set; max = maximum value in a data set; skew = skewness, the degree of asymmetry in a data set; kurtosis = a measure of extreme outliers; SE = standard error of the mean.  
Figure 5: Particle analysis of TEM images of washed sample at pH 6 (the pH was adjusted before the preparation of the AuNPs). The probability plot (**A**) and histogram (**B**) confirmed an approximately normal distribution of the mean diameter of the particles.  
Figure 6: SEM and EDS images of different samples. (**A**) SEM results of a washed pH 2 sample of glow-discharge-activated silicon wafer. (**B**) SEM results of a washed sample at pH 10 from glow-discharge-activated silicon wafer. (**C,D**) EDS analysis of a washed sample on a non-activated silicon wafer support. Drying the sample on a hydrophobic surface resulted in the formation of large aggregates of AuNPs at the edge of the dried sample. The individual spot positions marked in (**C**) and the corresponding spectra can be seen in (**D**). (**E,F**) EDS analysis of a washed sample at pH 10 on an activated silicon wafer support. The aggregation of AuNPs at the edge of the sample was minimized; however, the Au signal from the individual AuNPs was weak, while the intensity of the Si K\(\alpha\) peak from the silicon wafer support was predominant. The inserts in (**D,F**) show the effect of non-activated (**D**) and activated (**F**) silicon wafer supports on the final SEM sample formation after air-drying. Scale bars: (**A,B**) = 1 \(\mu\)m; (**C**) = 100 \(\mu\)m; (**E**) = 5 \(\mu\)m.