This paper presents a results on surface modification of polymers by Low Temperature Plasma (LTP). LTP processes have been utilized in a wide-range of technological and research areas, including microelectronics, gas lasers, polymers treatments, synthesis of novel materials and protective coatings. The characteristics of LTP is the existence of thermal non-equilibrium between the electrons, ions and the neutral particles. This property has made LTP an indispensable tool in material processing widely known as plasma processing. LTP can be generated in different modes such as: corona, glow, arc, dielectric barrier discharge (DBD) etc. The present paper is focused on DBD in atmospheric pressure generated with HV power supply operating at 50 Hz. The plasma was characterized by electrical and optical methods to determine the electron temperature (Te) and electron density (ne). The main objective of the study was to investigate the change in hydrophilicty of the polymers after the treatment in the plasma under different conditions. Effect of treatment time, applied voltage and working gas on the hydrophilicity of different polymers was studied. Plasma treated samples were characterized by contsct angle (CA) & surface energy measurement, SEM, AFM and FTIR analysis. The results showed that plasma treatment leads to significant increase in the hydrophility of the polymers.

The magic wavelengths for the 1S-2S and 1S-3S transitions of hydrogen and hydrogen-like systems, such as that of positronium and deuterium, were determined. Calculations were done by considering the polarizabiltiies of the ground state and of an excited state of interest, and the particular wavelength at which the AC Stark shifts cancel were found. Graphical analysis were employed to find the intersection of the polarizabilities for our different states. The graphs for the 1S-2S transitions of hydrogen and deuterium are constructed to show the most stable regions within the visible spectrum of light, but such is not the case for their 1S-3S transitions and both transitions of positronium. Our polarizabilities were provided by the 1S, 2S, and 3S position matrix elements of the Schrodinger Coulomb propagator, where the dimensionless variables within these quantities varied with respect to the state of the system, as well as its reduced mass. Though our neutral hydrogen and positronium systems are two-body in nature, we maintain the integrity of the two-body problem for deuterium by synthesizing a nucleic mass as the sum of the proton and neutron.

In this experiment, an atmospheric pressure dielectric barrier discharge (DBD)
generated with a water electrode is investigated by means of optical measurements and imaging. The discharge was generated using a high voltage (0-20kV) power supply operating at 10-30 kHz with water as one of the electrodes and borosilicate glass as a dielectric barrier of 2.5mm thickness. The discharge thus obtained was investigated by image analysis and optical emission spectroscopy. Our results showed that the distribution of micro-discharges depends significantly on the inter-electrode gap and applied voltage. Optical Emission Spectroscopy (OES) was used to analyze the spectra
of the discharge in the range of 200 nm to 1100 nm. Emission spectra of the discharge were measured and analyzed to determine the values of the electron temperature (Te) using the line-intensity ratio method. The results showed that Te depends on applied voltage and pressure inside the chamber. A comparison of different concentrations in water electrodes was done. The different Electron temperature was found to depend on the concentration and applied voltage. The values of Te were found to be 1.40 eV applied at 1kV voltage using 1% concentration. Similarly for 2kV, 4kV, 6kV ,8kV and 10kV the electron temperature were 1.40 eV, 1.11 eV,1.05 eV,1.0 eV and 0.95 eV respectively. For 5% concentration applied at 1kV voltage, the electron temperature is found to be
1.73 eV. Similarly for 2kV, 4kV, 6kV ,8kV and 10kV the electron temperature were 1.32 eV, 1.44 eV,1.15 eV,1.01 eV and 1.11 eV respectively. For 10% concentration applied at 1kV voltage, the electron temperature is found to be 1.66 eV. Similarly for 2kV, 4kV, 6kV ,8kV and 10kV the electron temperature were 1.58 eV,1.28 eV,1.27eV,1.13 eV and 1.11 eV respectively. The discharge was produced at various conditions for the study of the effectiveness of treatment on the surface property of Polyethylene terephthalate (PET). After the treatment of the sample in different treatment times: 10s, 20s, 40s, and 60s, the hydrophobic properties of the sample changed to hydrophilic. To investigate the effect of plasma treatment on Polyethylene terephthalate (PET) polymer contact angle was measured by using a goniometer with water as a testing liquid. The surface properties of the untreated and plasma-treated PET samples were characterized by contact angle measurement and surface energy analysis. Before treatment, the contact angle for the untreated sample was 76.6? and after treatment, its contact angle becomes 38.7?, 35.04?, 33.6?, and 31.6? respectively.

We have studied the effect of magnetic field on active electronegative plasma sheath properties and dust charging process in the sheath region for two different collisional models: constant ion mean free path (\gamma = 0) and constant ion mobility (\gamma = -1) using 1d3v fluid hydrodynamics model. It is found that the magnetic field strength and choice of collisional models have a significant effect on the active plasma sheath characteristics and charging of an isolated dust grain. The sheath criterion for an active electronegative magnetized plasma for both collisional models has been extended and the effects of neutral gas pressure, source frequency, obliqueness of magnetic field and initial electric field at sheath edge are graphically illustrated. There are two distinct regions, magnetic field and electric field dominant regions, which can be observed in the sheath region. The spatial distribution of plasma sheath parameters characterizing the plasma sheath region is systematically presented. It is found that the evolution of dust surface potential is affected by the magnitude of magnetic field and collisional models. Moreover, the total force experienced by an isolated dust grain in the sheath region rapidly increases close to the material surface and the magnitude of force is higher for larger dust grain.

Cold atmospheric pressure plasma jet (CAPPJ) has different applications such as in material processing and biomedical fields. CAPPJ has been generated by a high voltage (0-20 kV) power supply at an operating frequency of 20 kHz. This paper reports the characterization of CAPPJ and its application in the surface modification of high-density polyethylene (HDPE). Furthermore, atmospheric pressure plasma can be effectively used to remove surface contamination and chemically modify polymer surfaces. The chemical changes, especially oxidation and cross linking enhance the surface properties of the materials such as surface energy. The surface properties of the untreated and plasma-treated HDPE samples were characterized by contact angle measurement and surface free energy analysis.

We performed first-principles calculations to investigate electronic and optical properties of methylammonium tin bromide, CH3NH3SnBr3, molecules. Using GaussView, the initial structure of the molecule was created. Geometric optimization and frequency calculations were performed using Gaussian 09 on ground-state geometry of (CH3NH3SnBr3)n with n=1-4. Electrostatic Potential (ESP) Surfaces, HOMO-LUMO and the Vertical Excitation Energies were calculated and analyzed. Multiwfn 3.8 software was used to plot density of sates (DOS) and electronic properties were analyzed.