Organic dyes are known as hydrocarbon compounds, organic dyes consist of large molecules with a complex composition and It has a wide absorption and fluorescence spectrum in the visible and ultraviolet regions of the electromagnetic spectrum. Its molecular weight is large because it contains conjugate chains composed of carbon atoms linked by single other double, alternating bonds, which is called the chromophore system [1]. The chromophore is characterized by the absorption of light in the ultraviolet and visible regions, making the dye colored Because absorption transitions S1 to S0 occur in the visible region [2]. Chromophores are the group responsible for giving coloring to the molecule, so the dye molecule appears to be of a certain color to some dyes that absorb wavelengths within the range (800nm-400nm) [3].

polymers have become profitable for sensor technologies, because of their low-cost materials and their fabrication techniques being quite simple. in the past few decades, significant interest has been shown in polymer-based sensing materials, which exhibit a change in their absorption and/or fluorescence characteristics in response to an external stimulus. some examples of these stimuli include heat, deformation, chemicals, light, and others, which make the sensors useful for a wide range of technologies [4].

Polyvinylpyrrolidone (PVP) has been widely used in many fields, because of its outstanding chemical stability, transparent optical property, low cost, high performance of the products, and combined with the wide range of its properties. lt has enormous technical and economic importance, even though its degradation at high temperatures is still an intensively studied problem by many scientists [5]. lt can incorporate dye molecules to become colorful and functional. indeed, incorporating dyes into polymer-supported matrices, such as PVP, could keep them far away from the disturbance of external environments, which remarkably influences the spectral properties of dyes [6].

Nanotechnology is a modern field of science that plays a dominant role in our life. Nanotechnology deals with the production and manipulation of a particle structure ranging from about 1 to 100 nanometers [7]. Nanotechnology has many applications in medical chemistry, atomic physics, and other fields [8]. A large number of studies have focused on noble metal nanoparticles (NPs) such as gold (Au), silver (Ag), copper (Cu), and platinum (Pt) due to their Plasmonic properties [9,10]. Gold has a special blend of chemical and physical characteristics in states as macroscopic and macroscopic: On a scale microscopic, it is recognized for its yellow unique color, the potential for high redox, and chemically stable. lt’s electronic stucture outcome and comprehension that starts with the science of quantum along with Einstein’s relativity hypothesis [11]. The reason why nanoparticles of noble metals are distinguished is because of their plasmonic frequency in the visible region that gives the colors and ineresting optical properties and their unique ineraction with light [12].

Since it is widely used for the synthesis of new innovative materials, particularly for drilling microvias in high density printed circuit boards in microelectronic packaging, the laser ablation technique has sparked a lot of interest [31]. When a strong laser beam strikes a solid object, laser ablation plasma forms above the target’s surface. Laser ablation is a cost-effective and contaminant-free approach for a wide range of materials [13]. Laser ablation in liquid has opened up new vistas for nanostructure manufacture, and as a result, there has been a recent surge in research into the formation of nanostructures using this new technology. By contrasting established physical procedures such as chemical vapor deposition, vapor phase transport, and vacuum laser ablation with other methods, it is possible to arrive at a conclusion. Due to the great efficiency of the deleted components, and pure colloidal solutions of nanoparticles can form a product, liquid phase laser ablation offers several advantages, including the nanoparticles are fairly crystalline and can be obtained quickly, in one step, without any subsequent heat treatment. It clumps together in the colloidal solution [14].

Because of the unique features of outer polymer layers, polymer chains grafted/coated on the surfaces of gold nanoparticles can not only improve the stability of gold cores but also functionalize them. The "smart" nanocomposites made up of gold nanoparticles and intelligent polymers, in particular, exhibit important and exceptional characteristics [15, 16]. Due to live polymer components, this integrated work utilizes a simple path for multifunctional materials and permits a number of unique technological applications [17, 18]. Intelligent polymers are also referred to as "stimuli-responsive" or "environmentally sensitive" polymers in theory [1,20].

We can identify many visual factors by monitoring the spectrum of the shift in absorption and permeability.

Absorbance (A )

Absorption can be defined as the ratio between the intensity of absorbed light (IA) by matter and the intensity of fallen light (Io) given by the following equation [21]: \[A=\log_{10} \frac{I_A}{I_{\circ}}.\]

Transmittance (T)

It is the ratio between the intensity of the radiation emitted(IT) by it and the radiation falling on it (Io) called permeability, and is given in the following relationship [22]: \[T=\frac{I_T}{I_{\circ}}.\]

Absorption Coefficient

The absorption coefficient can be defined as the percentage of decrease in the energy of the incident radiation relative to the unit distance towards the direction of propagation of the wave within the medium, and the absorption coefficient depends on the energy of the photon (h\(\upsilon\)) and the properties of the material [23]. According to the Beer-Lambert law, the absorption coefficient is: \[\log(I /I)=2.303A= \alpha_{\circ}d .\] \[\alpha_{\circ}=\frac{2.303A}{d}.\]

Refractive Index (n)

The refractive factor can be defined as the ratio between the speed of light in the vacuum (C) to its speed within the material, the refractive factor is calculated from the following equation [24]: \[n=[(1+R)/((1-R)-(K^2+1)^{(1/2)}-(R+1)/R-1)],\] where they represent (n) refractive index, (R) the reflectivity, and (k) the Coefficient of extinction.

Materials Used

Nile blue molecular formula \((2C_{20}H_{2}ON_{3}O).SO_{4}\) and \(M_{W} = 732.85 g/mol\) were obtained from (Germany-Sigma-Aldrich) Polyvinyl pyrrolidone (PVP) \((C_{6}H_{9}NO)\), \(M_{W}=40000 g/mol\), and a gold plate, with a purity of 99.999 % was used obtained from (Germany-Sigma-Aldrich), Ethanol (Ethyl Alcohol) its molecular formula is \(C_{2}H_{5}OH\) and molecular weight 46.04 gm /mol, and all the materials were used as obtained. Figure 1 shows the molecular structures of (a) NB [25] (b) PVP [26].

Figure 1: The Molecular Structures of (a) NB (b) PVP

The Nile blue solutions used in the current study were prepared by dissolving the dye powder (0.018) gm in a volume (30) ml solvent ethanol where the concentration was obtained \((1\circ10-3)\) M according to the following equation [27]:

\[W=(V\times C\times M_{w})/1000,\] where \(W\): weight of the dissolved in material (g), \(M_{W}\): Molecular weight of the material (gm/ mole), \(V\): volume of the solvent (ml), and \(C\): the concentration (M).

The prepared solutions were diluted according to the following equation: \[C_{1} V_{1} = C_{2} V_{2},\] where

\(C_{1}\):primary concentration;

\(C_{2}\):new concentration;

\(V_{1}\): the volume before dilution;

\(V_{2}\):the volume after dilution.

Three concentrations were prepared (0.1,0.3 and 0.5 mM) respectively as shown in Figure 2(Left). Then prepare the polymer solution by taking a quantity of polymer powder of 0.5gm was taken and dissolving using 50ml of ethanol solvent. after which it was placed on the magnetic stirrer for 5 minutes at a temperature of 50 C to obtain a complete solution. The blend was prepared by adding equal amounts (1) of NB solution: (1) to the PVP solution ratio and placed on the magnetic stirrer for 30 minutes to obtain a complete solution as shown in Figure 2(Right).

Figure 2: The Solutions Samples of (Left) NB Dye Pure at Different Concentrations (Right) (NB dye+pvp) Blend at Different Concentrations

In the present work, gold nanoparticles were synthesized in ethanol using the PLA method by using Nd: YAG laser with (1064) nm, 100 MJ, 6 Hz, 3 min), where the particles were produced from the Au peeling when exposed to the laser pulse as shown in the Figure 3.

Figure 3: The PLA Method and Solution Sample of Au Nanoparticles in Ethanol

The surface morphology for the prepared solution sample could be observed by the SEM. Figure 4 observed that the Au NPs were homogenous and smooth this indicates a good method for the prepared sample.

Figure 4: SEM Image for Au Nps Solution in Ethanol

Solutions samples of (NB-PVP/AuNps) nanocomposites in ethanol solvent with different concentrations were prepared by adding 1 ml to all solutions of the (NB-PVP) blend as shown in Figure 5.

Figure 5: The Solutions Sample of ( NB dye-PVP/Au Nps) Nanocomposite at Different Concentrations in Ethanol

Figure 6 shows, in the pure case, the absorption and transmittance spectra of Nile blue dye solution showed an increase in absorption intensity due to an increase in the number of molecules due to absorption probability, which is consistent with Beer-Lambert Law, and the absorption peak shifted towards the longer wavelength (redshift). The dipole moment of the excited state causes the concentration to rise above that of the ground state. The transmittance spectra decreases with increasing concentration because, according to the same equation, transmittance is the inverse of absorbance [28]. Figure 6 shows the absorption and transmittance spectra of a solution(Nb) dye after adding(PVP) a polymer and stirring for [1, 31] minutes using a magnetic stirrer to obtain a solution (Nb/PVP). When the concentration of the polymer increases, the intensity of dye absorbance increases as well. When compared to the dye solution(Nb/pure), adding comparable amounts of polymer resulted in a noticeable decrease in absorbance intensity, and when it was added, a blue shift was noted at the top of the monomer peak. It should be mentioned that the interference between dye molecules and polymer molecules at partially electronic energy levels resulted in a drop in density. As a result of the aggregate dyes being dimmer and trimmer than the pure dye solution, the intensity of absorption reduces [29]. The mismatch was discovered in the width of the absorption spectra for low concentrations, with the biggest differences reported at high concentrations [32]. Because of the aforementioned rationale, permeability reduces as concentration rises. Figure 6 shows the absorption intensity of NB/PVP/AuNps revealed two peaks, the first at wavelength (525)nm representing the nanocomposite’s absorbance intensity and the second at wavelength(655)nm showing the dye absorption intensity. The influence of the method of pulsed laser ablation in liquids on the concentrations prepared from the dye was recorded, and it was noted that numerous possibilities arise in the addition process. One of these effects is a shift in wavelengths either in the direction of (redshift) or in the direction of (blueshift) when the quantity of nanoparticles inside the liquid increases (blueshift) This is dependent on the particle size of the nanoparticles that have been created. The intensity of absorption is the other impact, in which the concentration of the chemical is linked to an increase or reduction in absorption. When the size of the produced nanoparticles is tiny and added to the dye and polymer, the intensity of absorption decreases as the dye concentration decreases.

The absorption of blue Nile dye solution increases with increased concentration as well as absorption and refractive factors increase and transmittance decreases by increasing absorption because absorption is contrary to permeability and when the polymer solution is added to the dye solution in equal proportions the absorption begins to decrease due to the interaction between polymer and dye. the effects of gold nanoparticles there is an interference between its molecules and( NB-PVP) molecules in the molecular electronic energy levels, which leads to the split of the energy levels and as a result, the absorption intensity decreases.

This research paper received no external funding.

The authors declare no conflicts of interest.

All authors contributed equally to this paper. They have all read and approved the final version.

Informed consent was obtained from all participates in the study as needed.

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