## 3 Results and Discussion  
Figure 1 presents SEM images of the synthesized Ag particles. The laser parameters used to obtain the three types of Ag nanoparticles were 3 W-50 mm/s-10 nm, 8 W-25 mm/s-50 nm and 12.5 W-150 mm/s-50 nm, respectively. It was seen that the particle size increased with an increasing Ag film thickness and increased laser repetition rate. The corresponding particle heights for Figure 2 are 76, 288 and 515 nm, respectively. Figure 3 shows the relationship between the scanning speed and the laser input energy for initial Ag film thicknesses of 10 and 50 nm, respectively. As shown, both figures contained three distinct regions. In Region I, characterized by a low laser energy and high scanning speed, the energy was insufficient to prompt dewetting of the Ag film. As the scanning speed and laser energy increased, the input energy also increased and hence dewetting occurred, resulting in the formation of Ag particles (Region II). However, at excessive laser energies and low scanning speeds (Region III), the input energy led to the ablation of the Ag film rather than dewetting, and, consequently, no particles were formed. In general, the results confirm that the dewetting process is strongly dependent on the laser power and scanning speed. In particular, for a given scanning speed, a high laser energy results in the ablation of the Ag film, while a low laser energy results in an Ag film with many isolated island structures. For a constant laser energy, the particles tend to become larger with increasing scanning speeds due to corresponding reductions in the thermal energy accumulation. It is noted that this finding is consistent with those reported in previous studies [33; 34]. The results presented in Figure 3 confirm that the size of the particles produced in the dewetting process also depend on the thickness of the original Ag film. For a thicker film, the dewetting process can be performed at a higher energy, and particles with a micrometer scale are produced at all the corresponding scanning speeds. For a thinner film, particles can be obtained at a lower energy, and the particle size (nanometer) depends on the particular scanning speed applied [35]. Overall, the results show that the particle size decreases with an increasing laser energy and a decreasing film thickness. Figure 1: SEM images of Ag particles with a sizes of (**a**) 92 nm, (**b**) 570 nm and (**c**) 1.2 \(\upmu\)m.  
Figure 2: Cross-sectional images of Ag particles with different sizes of (**a**) 92 nm, (**b**) 570 nm and (**c**) 1.2 \(\upmu\)m.  
Table 1 shows the surface roughness (Ra) and contact angle measurements of the various Ag samples. The surface roughness increased with increasing particle sizes as a result of the greater particle height (see Figure 2). The contact angle also increased with increasing particle sizes. For example, the particles with a size of 92 nm and 1.2 um had contact angles of 43\({}^{\circ}\) and 73\({}^{\circ}\), respectively. Surface roughness is another factor that affected biological activities, suggesting that microbes have difficulty attaching and moving on an ultra-smooth surface [14]. Figure 4 presents OM images showing the conidia growth of the _C. gloosoperiodoides_ spores contacted with the different samples. In general, the results show that the treated samples (92 nm, 570 nm and 1.2 um) had significantly higher fungistatic properties than the control (glass) sample. The Ag sample with the largest particle size (1.2 um) achieved 100% fungistatics within a contact time of 5 min. For the sample with an Ag particle size of  
nm, 100% fungistatics was also achieved; however, the contact time increased to 10 min. For the smallest particle size of 92 nm, the sample contained 22 colonies after 15 min. In other words, full fungistatics was not achieved. However, overall, the results confirm that the conidia growth suppression ability of all the samples increased with increasing particle sizes and contact times.