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Light
Published in David M. Scott, Industrial Process Sensors, 2018
Gas-discharge lamps, such as those found in neon signs, use a high voltage source to ionize gas within the lamp; the ions are accelerated by the electric field and cause collisional excitation and additional ionization of the atoms in the gas. As the atoms decay back to their ground state, they emit photons whose wavelength is determined by difference in energy level ΔE between the two electronic states of the atom according to equation 4.6. The emitted light is therefore composed of distinct wavelengths that are characteristic of the atoms in the gas; the spectral output of such a lamp is therefore very different from that produced by an incandescent source. Fluorescent lights are gas-discharge lamps with a coating on the inside surface of the glass tube; this coating absorbs ultraviolet light and fluoresces in the visible spectrum.
Bactericidal efficiency of silver nanoparticles deposited on polyester fabric using atmospheric pressure plasma jet system
Published in The Journal of The Textile Institute, 2022
Giovanni M. Malapit, Ronan Q. Baculi
Plasma is an assemblage of free charged particles and neutrals in random motion which are, on the average, electrically neutral (Brown, 2004; Lieberman & Lichtenberg, 1994). This dynamic mix of neutrals, ions, electrons and even photons, radicals, excited species, molecular and polymeric fragments contribute in the functionalization of material surfaces with minimal effect to the whole properties of the materials (Ocampo et al., 2018; Shishoo, 2007). While thermal plasmas are mostly applied for metal hardening and surface cleaning, non-thermal equilibrium plasmas or cold plasmas are fitting candidates for nanoscale surface modification of natural or synthetic polymeric materials such as textiles. Cold plasmas are characterized by having electrons with relatively high temperature but their atomic and molecular species are at near ambient temperature making them suitable for pre-treatment and finishing of textile fabrics without affecting their bulk properties (Hong & Sun, 2008). Non-thermal plasma was generated in this work using a novel atmospheric pressure plasma jet (APPJ) system. This device produces low-pressure plasma with temperatures from 25 to 200 °C that can be used for materials processing. Single gases or mixture of gases flow through a pair of electrodes encapsulated by a glass tube. High voltage from a neon sign transformer is applied to the electrodes to form a glow discharge and with the flow of gases, the plasma discharge is plumed out of the nozzle (Ocampo et al., 2018).
Atmospheric pressure plasma deposition of silver nanoparticles on bark fabric for bacterial growth inhibition
Published in The Journal of The Textile Institute, 2023
Ronan Q. Baculi, Giovanni M. Malapit, Leah E. Abayao
Plasma treatment of the samples was done using atmospheric pressure plasma jet (APPJ) system (Figure 2). A pair of 99.95% silver electrodes was inserted on opposite ends of a cross-tube glass. Plasma was generated using a mixture of argon and oxygen gases at a discharge voltage of 15 kV from a 450 W neon sign transformer to produce a discharge between the 5 mm distance of the electrodes. The flow rates of argon and oxygen gases were maintained at 15 LMP and 5 LPM, respectively. The textile samples (0.5 cm x 0.5 cm) were positioned 5 mm from the nozzle and were subjected to plasma treatment using 1 min, 3 min, and 5 min plasma exposure time. A sample without plasma exposure served as the control.