## 3 Results and Discussion
### Optical Properties  
The UV-Visible absorption spectrum displayed in Figure 5 show the electromagnetic radiation absorbed by Se NPs. The results confirm the existence of two absorption bands centered at the wavelength of \(\lambda_{1}=458\) nm and \(\lambda_{2}=622\) nm. The middle band centered at \(\lambda_{1}=458\) nm is related to selenium nanoparticles, while the strong band centered at \(\lambda_{2}=622\) nm can be attributed to surface plasmonic resonance and the small size of  
Figure 4: TEM images of Se NPs synthesized at **(A)** 200 nm magnification, **(B)** 40 nm magnification and **(C)** the histogram size distribution using _Withania somifera_ extract. nanoparticles prepared by the synthesis process. Our result is consistent with the results of the work published in 2020 and 2018 by [PERSON] et al. and [PERSON] et al., respectively [30,31]. Figure 6 indicates the relation between the optical absorption coefficient and the wavelength of Se NPs prepared by the green method. The results confirm that the sample has high absorption coefficient values in the visible region, reaching its peak at the wavelength \(\lambda_{2}=622\) nm. The current results are consistent with the results of the works published in 2013 by [PERSON] et al. and in 2019 et al. by [PERSON] [32,33]. Figure 5: UV-visible absorbance spectra of Se NPs. Figure 6: Absorption coefficient as function of wavelength of synthesized Se NPs. The dependence of the optical absorption coefficient with the photon energy helps to study the band structure and the type of transition of electrons. By using the absorption data, the optical absorption coefficient \((\alpha)\) can be deduced by applying [PERSON]'s law [34]:  
\[\alpha=\frac{2.3030\times A}{e} \tag{3}\]  
where \(A\) is the maximum absorbance, and \(e\) is the sample thickness \((e=0.003\ \mathrm{cm})\). The inter-band absorption theory shows that the absorption coefficient near the threshold versus incident energy is given by the following [PERSON]'s relation [35]:  
\[\alpha h\
u=B\big{(}h\
u-E_{g}\big{)}^{n} \tag{4}\]  
where \(B\) is the probability parameter for the transition and \(E_{g}\) the optical gap energy. For allowed direct transitions, the coefficient \(n\) is equal to \(\frac{1}{2}\), and for indirect allowed transitions, \(n=2\). Due to the direct band gap, the compound under study has an absorption coefficient \((\alpha)\) obeying the following relation for high photon energies \((h\
u)\):  
\[\alpha h\
u=B\big{(}h\
u-E_{g}\big{)}^{\frac{1}{2}} \tag{5}\]  
The \(E_{g}\) value corresponding to direct band gap transitions (see Figure 7) can be calculated via the \((\alpha h\
u)^{2}\) versus \(h\
u\) by using the following formula:  
\[(\alpha h\
u)^{2}=B\big{(}h\
u-E_{g}\big{)} \tag{6}\]  
The values of \(E_{g}\) were estimated from the intersection of the extrapolated linear part of the \((\alpha h\
u)^{2}\) curves with the energy axis. Figure 7 shows the variation in \((\alpha h\
u)^{2}\) versus \(h\
u\) before and after irradiation with laser beams for Se NPs. The results confirm that the energy gap was approximately 1.6 eV. The present results are consistent with the authors' findings [36; 37]. Figure 7: Tauc plot of prepared Se NPs. Table 3 shows that treatment with nanosehenium led to a significant improvement (\(p\leq 0.05\)) in the value of the medium and high damage, as the value decreased significantly compared to the streptozotocin group. The results also showed the parameters of tail length (px), tail DNA (%) and tail mean moment according to Table 4. The qualitative mean value of the SeNPs marked with the letter D is not significantly different from the control sample, but the qualitative mean values of STZ are different. Additionally, those marked with the letter A were significantly different from the negative control group (\(p\leq 0.05\)). On the other hand, the percentage of DNA was studied to evaluate the integrity of sperm.