Various parameters that directly related to the ion beam with composite interactions is determined using the SRIM simulation program [29]. Figure 2 displays the outcomes of the SRIM conducted on 5 keV argon with PVA/CuO in dispersed range of 1000 Å. Figure 2 (a) illustrates the incoming ion starts to ionize the surface. The ionization effects that result from the argon ions penetrating the target is some higher than those that come from the recoils target atoms. The findings demonstrate that the penetration ions and recoil atoms have a significant effect on target ionization. Figure 2(b) shows collision events of the argon ion in the composite vacancies. Consequently, the inbound ions permeate the film and cause the ion-induced alterations by surface-area localized dissipation of heat.

Figure 3 displays the XRD structures of PVA/CuO films that have been exposed to different fluences; 3x1017, 6x1017, and 9x1017 ions.cm− 2, respectively. The XRD analysis of PVA/CuO revealed that the (101) crystal plane has a peak at 2θ = 19.5°, suggesting the semi-crystalline feature of PVA. Additionally, the (111) reflection CuO plane may have a minor peak at 2θ of 38.8° [30]. Due of the increased contact between PVA and CuO for the irradiated samples, the peak's intensity reduced with the ion beam fluence. Moreover, it is evident that the distinct diffracted peaks remain in their original positions following the films' exposure to ion beams. There is, nevertheless, a variation in peak intensity. This results in an ordered to an unarranged pattern in the crystal structure, which is caused by the chain scission of molecular strings [31]. Furthermore, the generation of defects as a result of increased radiation fluence leads to the development of disordered structures, which is the cause of the intensity drop [32].

The mean size of the crystallite (D) of the CuO in the PVA/CuO composite [33]is given by:

$$\text{D}=\frac{0.94{\lambda } }{{\beta }\text{C}\text{O}\text{S}{\theta }}\dots \dots \dots \dots \dots \dots . \left(1\right)$$

where λ indicates the wavelength and β is the full width intensity of the (111) plane. Moreover, the next formula is used to determine the samples' particle diameter (R) [34] by:

$$\text{R}=\frac{{\lambda }}{\text{sin}{\beta }\text{cos}2{\theta }}\dots \dots \dots \dots .\left(2\right)$$

Consequently, for 9x1017 ions.cm− 2 irradiated PVA/CuO, the particle size D and diameter R fall to 11.2 nm and 149.1 µm, respectively, from 16.5 nm and 218.2 µm of PVA/CuO composite. Additionally, the dislocation density (δ) parameter [34] is given by:

$${\delta }=\frac{1}{{\text{D}}^{2}}\dots \dots \dots \dots \dots \dots \dots ..\left(3\right)$$

As shown in Table 1, for PVA/CuO composite and at a fluence of 9x1017 ions.cm− 2, the dislocation density is enhanced from 3.01×10− 3 to 4.75×10− 3 lines/m2. This is due to the changes in inter-planar distance. The strain (ε) is given by [35]:

$${\epsilon }=\frac{{\beta }}{4\text{tan}{\theta }}\dots \dots \dots \dots \dots ..\left(4\right)$$

It is observed that the lattice strain increases from 0.072×10− 3 of the pure PVA/CuO composite to 0.085×10− 3 for the fluence of 9x1017 ions.cm− 2 irradiated film. These results lead to both the particles' misalignment and decreased size. Lastly, the distortion parameters (g) is computed by [35].

$$g=\frac{\beta }{\text{tan}\left(\theta \right)}\dots \dots \dots \dots \dots \dots \dots \dots . \left(5\right)$$

It is evident that following the fluence of 9x1017 ions.cm− 2 irradiated composite, the g rises from 10.7 for the pure PVA/CuO film to 14.1, which further supports the production of a disordered system in the composite.

Table 1

microstructural characteristics of the pure and irradiated PVA/CuO

The samples | D [nm] | R [µm] | δ [10− 3 lines/m2] | ε [10− 3] | g (%) |

PVA/CuO | 16.5 | 218.2 | 3.01 | 0.072 | 10.7 |

3x1017 ions.cm− 2 | 14.6 | 195.7 | 3.04 | 0.078 | 10.6 |

6x1017 ions.cm− 2 | 13.1 | 175.8 | 4.73 | 0.082 | 13.3 |

9x1017 ions.cm− 2 | 11.2 | 149.1 | 4.75 | 0.085 | 14.1 |

As seen in Fig. 4, FTIR spectra analysis is used to determine the vibrational bands and functional groups of both pure and irradiated PVA/CuO. The vibrational stretching of PVA is observed as occurring in a broad band at 3275 cm− 1. An additional band for stretching of C-H at 2925 cm− 1 is found. The C = O vibrational stretching is detected at 1720 cm− 1. A Peak is found at 1368 cm− 1 and is attributed to PVA's C-H bending [36]. The band of absorption detected at 1245 cm− 1 is determined to be -CH2 wagging. The -CH2 vibrational stretching is seen by the absorption band at 822 cm− 1. C-O-C vibrational stretching is recognized as the peak at 1092 cm− 1 [37]. The interaction between PVA and CuO filler is indicated by the lowering of peak intensity for the irradiated PVA/CuO. Additionally, the bands shift following the irradiation process shows how abundant electrons are, which improves the irradiated composite's optical properties [38].

The extinction coefficient (K) is estimated by [39].

$$K=\frac{{\alpha }{\lambda }}{4{\pi }}\dots \dots \dots \dots \dots \left(6\right)$$

Figure 5(a) displays the photon wavelength and the extinction coefficient of both the original and irradiated PVA/CuO films. Because of the defects density increases with irradiation process, the absorbance coefficient (K) grows. The reflectance R of the pure and treated films is seen in Fig. 5(b). The irradiated and un-irradiated films maintain a consistent reflectance at higher wavelengths. In addition, as the irradiation fluence increases, the reflectance rises.

The refractive index (n) [40] is estimated by following equation:

$$n=\frac{(1+R)}{(1-R)}+\sqrt{\frac{4R}{{\left(1-R\right)}^{2}}}-{K}^{2}\dots \dots \dots \dots \dots \dots \left(7\right)$$

Figure 6a displays the refractive index n of the PVA/CuO nanocomposite films before and after the irradiation process. The original film's refractive index is 1.014, meanwhile, after being subjected to 3x1017 ions cm− 2 and 6x1017 ions cm− 2, respectively, it increased to 1.020 and 1.030. As a result of the formed free radicals between the various chains of the irradiated samples, the refractive index rises with ion irradiation [41, 42]. The optical conductivity (σopt) of the pure and irradiated films is given by [43].

$${{\sigma }}_{opt}=\frac{\alpha nc}{4\pi }\dots \dots \dots \dots \dots \dots \left(8\right)$$

Figure 6b shows the wavelength-dependent shift in optical conductivity for both the un-irradiated and irradiated films. The optical conductivity of the films is enhanced due to a higher absorption coefficient caused by the localized state densities in the band structure.

The complicated dielectric constant is separating into two components: real \({\epsilon }_{r}\) and imaginary εi that given by the following equation [44] :

$${\epsilon }={\epsilon }_{r}+i{{\epsilon }}_{i}\dots \dots \dots \dots \left(9\right)$$

The εr is given by [45]:

$${{\epsilon }}_{r}={n}^{2}-{\text{K}}^{2}\dots \dots \dots \dots \dots \left(10\right)$$

Figure 7(a) shows the εr with wavelength (λ) of the original and irradiated films. It has been observed that the εr steadily rises with ion irradiation. The formation of bonds of different chains, raises photon energy. Moreover, the imaginary portion (εi ) is given as following [46]:

$${{\epsilon }}_{i}=2 n k\dots \dots \dots \dots \dots \left(11\right)$$

Figure 7(b) displays the εi with λ of the irradiated and pristine samples. It is noteworthy that the density and refractive index of the PVA/CuO film rise as a result of the εi steadily increasing with ion fluence.

Wemple and DiDomenico connection [47] is used to estimate the single oscillator by:

$$\frac{1}{{n}^{2}-1}=\frac{{E}_{O}}{{E}_{d}}-\frac{1}{{E}_{O} {E}_{d}}{\left(h{\nu }\right)}^{2}\dots \dots \dots \dots .\left(12\right)$$

The dispersion energy is represented by Ed, and the single oscillator energy is denoted by Eo. As a result, the (n2-1)−1 and (hv)2 of the pure and irradiated films is plotted in Fig. 8(a). The linear fit part's intercept and slope can be used to get the Eo and Ed. Furthermore, the static refactive index (no) can be calculated [48] as the following:

$${\text{n}}_{o}={(1+\frac{{E}_{d}}{{E}_{O}})}^{1/2}\dots \dots \dots \dots \left(13\right)$$

Thus, by using the relation \({\epsilon }_{\infty }\) = (no)2, it is possible to determine the zero frequency dielectric constants (\({\epsilon }_{\infty }\)). Table (2) lists the optical parameters of PVA/CuO nanocomposite, including Eo, Ed, and \({\epsilon }_{s}\). For the irradiated fluence 6x1017 ions.cm− 2, it is seen that Ed rises from 0.098 eV to 0.26 eV and the Eo increases from 3.25 eV for the pure film to 3.89 eV. The Spitzer-Fan model is used to calculate to the \({\epsilon }_{l}\) and the ratio of N/m* by [49].

$${{\epsilon }}_{r}={\epsilon }_{l}-\left(\frac{{e}^{2}}{4 {{\pi }^{2}{\epsilon }_{s}c}^{2} }\frac{N}{{m}^{*}}\right){\lambda }^{2}\dots \dots \dots \dots ..\dots \left(14\right)$$

The dielectric free-space is represented by εs, the electron charge by e, and the speed of light by c. Consequently, the relationship of the dielectric constant and λ2 at a greater wavelength is shown in Fig. 8(b). The εl and N/m*, respectively, can be determined by utilizing the intercept and slope of the straight segments of the detour of Fig. 8(b).

Table 2

The no, ε∞, Ed, Eo, εl, and N/m*of pure and treated PVA/CuO films

The samples | no | ε∞ | Ed (eV) | Eo (eV) | \({\epsilon }_{l}\) | N/m* x1039 (cm3.g) |

PVA/CuO | 1.014 | 1.028 | 0.098 | 3.25 | 1.036 | 0.002 |

3x1017 ions.cm− 2 | 1.020 | 1.04 | 0.140 | 3.86 | 1.070 | 0.003 |

6x1017 ions.cm− 2 | 1.030 | 1.06 | 0.26 | 3.89 | 1.086 | 0.004 |

9x1017 ions.cm− 2 | 1.007 | 1.01 | 0.24 | 1.67 | 1.028 | 0.0017 |

The resonance plasma frequency (Wp) is determined by [50]:

$${\text{W}}_{p}=\frac{{e}^{2}}{{\epsilon }_{o}}x\frac{N}{{m}^{*}}\dots \dots \dots \dots ..\dots \left(15\right)$$

Changes in \({\epsilon }_{l}\), N/m*, and Wp occurred by the irradiation fluences: 3x1017, 6x1017, and 9x1017 ions.cm− 2 are shown as listed in Table 3. The medium oscillator (λo) and long-wavelength refractive index (n∞) were evaluated using the single term Sellmeier oscillator [51]:

$${(n}_{\infty }^{2}-1)/({n}^{2}-1)=1-({\frac{{\lambda }_{o}}{\lambda })}^{2}\dots \dots \dots \dots \dots \left(16\right)$$

Thus, as seen in Fig. 8(c), relation (n2-1)−1 and \(\lambda\)−2 are used to produce n∞ and \({\lambda }_{o}\) from the linear part's intercept and slope, respectively, as given in Table (3). Additionally, the next equation can be used to estimate the values of single oscillator length (So) by[52]:

$${S}_{o}={(n}_{\infty }^{2}-1)/{{(\lambda }_{o})}^{2}\dots \dots \dots \dots \dots \left(17\right)$$

It is evident that the n∞ and So progressively rise as ion beam affects, and conversely, the \({\lambda }_{o}\) values drop for the irradiated films. Meanwhile, the following relation [53] links the incident photon wavelength and \({{\epsilon }}_{i}\) in the Drude model:

$${{\epsilon }}_{i}=\frac{1}{4{\pi }^{3}{\epsilon }_{o}}\left(\frac{{e}^{2}N}{{c}^{3}{m}^{*}\tau }\right){\lambda }^{3}\dots \dots \dots \dots \left(18\right)$$

Plotting the \({{\epsilon }}_{i }\) and λ3 which are specified in Table (3) as illustrated in Fig. 8(d) yields the relaxation time (τ). It is shown that for irradiated 9x1017 ions.cm− 2, the time relaxation progressively decreases from 21x10− 15 (sec) for PVA/CuO to 2.9x10− 15 (sec). These results showed that ion beam irradiation enhanced nanocomposite films, which makes the nanocomposite suitable for use in high-speed optoelectronic devices.

The following formula [54] can be used to characterize a material mode's nonlinear optical (NLO) response:

$$P={{\chi }}^{\left(1\right)}E+{{\chi }}^{\left(2\right)}{E}^{2}+{\text{X}}^{\left(3\right)}{E}^{3}\dots \dots \dots \left(19\right)$$

Where χ (1) is the first linear, χ (2) is the second-order NLO, and χ (3) is the third-order NLO. P represents polarization in this example. The relationships shown below are utilized to estimate X(1) and χ (3) [55].

\({{\chi }}^{\left(1\right)}=\frac{({n}^{2}-1)}{4\pi } \dots \dots \dots ..\) (20), and

$${{\chi }}^{\left(3\right)}=A{\left({X}^{\left(1\right)}\right)}^{4}\dots .\dots \left(21\right)$$

The NLO refractive index \(n\left(\lambda \right)\) is given by [56]:

$$n\left(\lambda \right)={n}_{o}\left(\lambda \right)+{n}_{2}\left({E}^{2}\right)\dots \dots \dots \dots \left(22\right)$$

The refractive index (\({\text{n}}_{2}\)) can be used to compute the NLO refractive index [56].

$${n}_{2}=\frac{12\pi {X}^{\left(3\right)}}{{n}_{o}}\dots \dots \dots \dots \dots \left(23\right)$$

Figures 9(a,b) display the change in \({{\chi }}^{\left(1\right)}\) and \({{\chi }}^{\left(3\right)}\) with wavelength (λ) for the pure and irradiated films. Ion irradiation increases both \({{\chi }}^{\left(1\right)}\) and \({{\chi }}^{\left(3\right)}\) values. This is because of the defect centers, which cause local polarizabilities that rise with radiation [57]. Moreover, the variation in \({n}_{2}\)with wavelength is shown in Fig. 9(c). Similar to χ(3), the n2 increases progressively with the ion beam.

Table 3

The Wp, n∞, λo, So, and \(\tau\) of pure and treated irradiated PVA/CuO films.

The samples | \({\text{W}}_{p}\) x 1012 (sec− 1) | \({\text{n}}_{\infty }\) | λo (nm) | So x 1012 (m− 2) | \(\tau\) x 10− 15 (sec) |

PVA/CuO | 0.0006 | 1.015 | 407 | 0.63 | 21 |

3x1017 ions.cm− 2 | 0.0009 | 1.026 | 471 | 0.62 | 9.1 |

6x1017 ions.cm− 2 | 0.0012 | 1.032 | 537 | 0.47 | 6.3 |

9x1017 ions.cm− 2 | 0.0015 | 1.047 | 834 | 0.15 | 2.9 |