Physics Commons^™

Diagnostics Of A Large Volume Pin-To-Plate Atmospheric Plasma Source For The Study Of Plasma Species Interactions With Cancer Cell Cultures, Laurence Scally, Chaitanya Sarangapani, Brijesh Tiwari, Renee Malone, Hugh Byrne, James Curtin, P.J. Cullen

Articles

A large gap pin-to-plate, atmospheric pressure plasma reactor is demonstrated as means of in vitro study of plasma species interactions with cell cultures. By employing optical emission and optical absorption spectroscopy, we report that the pin-to-pate plasma array had an optimal discharge frequency for cell death of 1000 Hz in ambient air for the target cancer cell line; human glioblastoma multiform (U-251MG). The detected plasma chemistry contained reactive oxygen and nitrogen species including OH, N₂, N₂⁺, and O₃. We show that, by varying the plasma discharge frequency, the plasma chemistry can be tailored …

Birefringent Optofluidic Gratings, Sergio Calixto, Jose L. Garcia-Cordero, Diana F. Cedillo-Alcantar, Izabela Naydenova, Guillermo Garnica

Articles

A set of parallel microfluidic channels behaving as a diffraction grating operating in the Raman-Nath regime has been fabricated and studied. The diffraction efficiency of such structure can be tuned by selecting a liquid with a particular refractive index and/or optical anisotropy. Alternatively the optical properties of the liquid can be characterised by measuring the diffraction efficiency and the state of polarization of the diffracted beam. In this work, the microfluidic channels under study have been filled with penicillin molecules dissolved in water. Due to the chirality of the penicillin, the liquid has been found to have circular birefringence of …

Impact Of Plasma Treatment On Acoustic Properties Of Natural Cellulose Materials, Sanja S. Pavlović, Snežana B. Stanković, Andrijana Žekić, Miloš Nenadović, Dušan M. Popović, Vladimir Milosavljevic, Goran B. Poparić

Articles

Low-temperature plasma is widely used in many surface treatment technologies for modifications of the physical properties of different polymeric materials. In the present work, we have examined the modification of acoustical properties of natural cellulose materials (cotton, hemp) by the radio-frequency argon plasma. We have observed an increase of the sound absorption coefficient due to the plasma treatment for certain range of applied powers. An analysis of elementary processes which happened during plasma–material interaction was conducted. Additional analyses related to material characterizations were performed in order to resolve structural and chemical changes of plasma treated materials. The micro-mechanical modification of …

Significance Of A Non-Thermal Plasma Treatment On Ldpe Biodegradation With Pseudomonas Aeruginosa, Laurence Scally, Miroslav Gulan, Lars Weigang, Patrick Cullen, Vladimir Milosavljevic

Articles

The use of plastics has spanned across almost all aspects of day to day life. Although their uses are invaluable, they contribute to the generation of a lot of waste products that end up in the environment and end up polluting natural habitats such as forests and the ocean. By treating low-density polyethylene (LDPE) samples with non-thermal plasma in ambient air and with an addition of 4% CO2, the biodegradation of the samples can be increased due to an increase in oxidative species causing better cell adhesion and acceptance on the polymer sample surface. It was, however, found that the …

Evaluation Of The Effect Of Plasma Treatment Frequency On The Activation Of Polymer Particles, Hisham Abourayana, Vladimir Milosavljevic, Peter Dobbyn, Denis Dowling

Articles

This study investigates the influence of treatment frequency (1–150 kHz) on the atmospheric plasma activation of both silicone and polyethylene terephthalate (PET) particles. These polymer particles with diameters in the range 3–5 mm, were treated using either helium or helium/oxygen gas mixtures, in a barrel atmospheric plasma system. The level of polymer particles activation was monitored using water contact angle measurements. The effect of plasma treatment frequency on barrel heating was monitored using an infrared thermographic camera, the maximum barrel temperature after 15 min treatment was found to be 98 °C at a frequency of 130 kHz. Optical emission spectroscopy …

Spectroscopic Characterization Of A Radio-Frequency Argon Plasma Jet Discharge In Ambient Air, Patrick Cullen, Vladimir Milosavljevic

Articles

This study includes a detailed experimental investigation of the spatial and temporal spectroscopic emission of an argon plasma jet discharge. The study is carried out in ambient air and quenching by inflowing air species is considered. The optical emission spectroscopy of neutral atomic spectral lines and molecular bands, over a range of plasma process parameters, is investigated. Wavelength-resolved argon optical emission profiles are used to monitor the electron energy distribution function and the density of argon metastable atoms. The experimental data indicates that the argon flow rate, in a confined open-air plasma discharge, limits the impact of molecular oxygen in …

The Contribution Of Non-Thermal And Advanced Oxidation Technologies Towards Dissipation Of Pesticide Residues, N. Misra

Articles

Background

The use of pesticides has stabilised the food production to a great extent and their usage cannot be avoided anymore. Nevertheless, common food processing operations always allowed dissipating pesticide residues in foods to some extent. Within the food science community and the food processing sector, non-thermal food technologies are being researched and commercialised at a great pace over the past three decades.

Scope and Approach

In this review we provide a critical analysis of the literature pertinent to the fate of pesticide residues during non-thermal processing of solid and liquid foods. We also identify the opportunities for further development …

Quantitative Assessment Of Blood Coagulation By Cold Atmospheric Plasma, Caitlin Heslin, Daniela Boehm, Vladimir Milosavljevic, Michelle Laycock, Patrick Cullen, Paula Bourke

Articles

Cold atmospheric plasma (CAP) is produced by ionizing a chosen gas, thereby creating charged and reactive species. The reactive species generated are capable of inducing a range of biomedically relevant interactions including blood coagulation. However, the underlying biochemical processes of plasma-assisted blood coagulation are largely unknown, and data quantifying blood clot formation or the impact of system parameters on the intensity of the blood clot are scarce. In this study, blood coagulation was quantified by measuring hemoglobin absorbance. System parameters of the kINPen plasma jet were investigated and compared, including treatment time, distance from the plasma source and gas flow …

In-Package Atmospheric Pressure Cold Plasma Treatment Of Cherry Tomatoes, N. Misra, Kevin Keener, Paula Bourke, J Mosnier, Patrick Cullen

Articles

Cold plasma is increasingly under research for decontamination of foods, especially fresh fruits and vegetables. The effect of cold plasma on food quality, however, remains under researched. This study investigates the effects of cold plasma generated within a sealed package from a dielectric barrier discharge on the physical quality parameters and respiration rates of cherry tomatoes. Respiration rates and weight loss were monitored continuously, while other parameters are reported at the end of storage period. Differences among weight loss, pH and firmness for control and treated cherry tomatoes were insignificant towards the end of storage life. Changes in respiration rates …

In-Package Atmospheric Pressure Cold Plasma Treatment Of Strawberries, N. Misra, Paula Bourke, Patrick Cullen, Sonal Patil

Articles

The ability to generate low temperature plasma at atmospheric pressure offers new opportunities to decontaminate biological materials, including fresh foods. In this study, strawberries were treated with atmospheric cold plasma (ACP), generated with a 60 kV dielectric barrier discharge (DBD) pulsed at 50 Hz, across a 40 mm electrode gap, generated inside a sealed package containing ambient air (42% relative humidity). The current-voltage characteristics revealed that the plasma operated in the filamentary regime. The background microflora (aerobic mesophillic bacteria, yeast and mould) of strawberries treated for 5 min was reduced by 2 log 10 within 24 h of post-ACP treatment. …

In-Package Nonthermal Plasma Degradation Of Pesticides On Fresh Produce, N. Misra, Shashi Pankaj, Tony Walsh, Finbarr O'Regan, Paula Bourke, Patrick Cullen

Articles

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues. A cocktail of pesticides, namely Azoxystrobin, Cyprodinil, Fludioxonil and Pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post- plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24 h in-pack storage. …

Diagnostics Of An O2–He Rf Atmospheric Plasma Discharge By Spectral Emission, Vladimir Milosavljevic, Mick Donegan, Patrick Cullen, Denis Dowling

Articles

In this paper optical emission spectroscopy (OES) is used as a Diagnostic technique for the measurement of atomic and molecular spectral emissions generated using a helium rf industrial atmospheric plasma jet system. The OES of neutral atomic spectral lines and molecular bands are investigated over a range of plasma process parameters.
Wavelength resolve optical emission profiles suggest that the emission of helium’s spectral lines shows that the high energy electrons have a larger influence than helium metastables on the overall spectral emission. Furthermore, the experimental data indicates that the use of high helium flow rates, in any confined open air …

Dc Pulsed Atmospheric Pressure Plasma Jet Image Information, Denis P. Dowling, F T. O'Neill, Vladimir Milosavljevic, Victor J. Law

Articles

This paper presents optical imaging and optical emission spectroscopy (OES) data of an atmospheric-pressure plasma jet. It is shown how the visual information and OES information of the air discharge are related as the blown arc extends from the nozzle (2-4 mm) with a molecular nitrogen rotational temperature on the order of 1700 K and the flowing afterglow beyond this region is dominated by the cooler (300-K) NO-O chemiluminescent reaction that produces NO₂ species.

Raman Scattering Analysis Of Silicon Dioxide Single Crystal Treated By Direct Current Plasma Discharge, Dusan M. Poparic, Vladimir Milosavljevic, Andrijana Zekic, N Romcevic, Steven Daniels

Articles

Low-k materials such as silicon dioxide (SiO2) play an important role in the semiconductor industry. Plasma has become indispensable for advanced materials processing. In this work a treatment of SiO2single crystal by direct current plasma discharge is studied in detail. Offline metrology is conducted for silicon dioxide wafers by Raman scattering, energy-dispersive x-ray spectroscopy, and ellipsometry. Broad Raman peak at around 2800 cm−1 is observed for the treatedSiO2 wafers. Effects of plasma treatment on position of this peak are reported in the paper. An analysis of this correlation could be a framework for creating virtual etch rate sensors, which might …

Hand-Held Flyback Driven Coaxial Dielectric Barrier Discharge: Development And Characterization, Victor J. Law, Vladimir Milosavljevic, Neil O’Connor, James F. Lalor, Steven Daniels

Articles

The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10–33 W to generate a 1.2–1.6 kV 3.5 μs pulse. An argon discharge breakdown voltage of ∼768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5–10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in …

Real-Time Plasma Controlled Chemistry In A Two-Frequency, Confined Plasma Etcher, Vladimir Milosavljevic, Albert R. Ellingboe, Cezar Gaman, John V. Ringwood

Articles

The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor …

Practical Sensor For Measurement Of Nitrogen, Dusan Popovic, Vladimir Milosavljevic, Steven Daniels

Articles

This paper presents a method for precise measurement of atomic and molecular nitrogen in an oxygen-nitrogen dc plasma. This is achieved by monitoring the intensities of the atomic nitrogen spectral line at 821.6 nm and the molecular nitrogen bandhead at 337.1 nm, relative to the atomic oxygen spectral line at 844.7 nm. Oxygen is one of the most frequently used gases for surface chemical treatment, including deposition and etching, therefore the ability to measure and control the process and chemical composition of the process is essential. To validate this oxygen actimometry method for N2-xO2 (where x varies from 0 to …

Measured Stark Widths And Shifts Of The Neutral Argon Spectral Lines In 4s–4p And 4s–4p′ Transitions, Vladimir Milosavljevic, Albert R. Ellingboe, Stevan Djenize

Articles

We investigate the Stark widths (W) and the shift (d), of the seven neutral argon (Ar I) spectral lines from the 4s–4p and 4s–4p′ transitions. The line shapes are measured in a linear, low-pressure, optically thin pulsed arc discharge at about 16 000 K electron temperature (T) and about 7.0 × 10²² m^{− 3} electron density (N). The new data separates the electron width (W_e) and ion width W_i from the total Stark width (W_t), as well the separation of electron total Stark …

Stark Width And Shift Of The Neutral Argon 425.9 Nm Spectral Line, Vladimir Milosavljevic, Vida Zigman, Stevan Djenize

Articles

The Stark parameters, the width (W) and the shift (d), of the neutral argon (Ar I) 425.9 nm spectral line have been studied in a linear, low-pressure, optically thin pulsed arc discharge. The line shapes are measured in three different plasmas at about 16,000 K electron temperature (T) and about 7.0×10²² m⁻³ electron density (N). The separate electron and ion contributions to the total Stark width (W_t), i.e. W_e and W_i, as well as to the total Stark shift (d_t), i.e. …

Transition Probabilities In Kr Ii And Kr Iii Spectra, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic

Articles

On the basis of the relative line intensity ratio (RLIR) method, transition probability values of the spontaneous emission (Einstein's A values) of 14 transitions in the singly (Kr II) and 7 transitions in doubly (Kr III) ionized krypton spectra have been obtained relatively to the reference A values related to the 435.548 nm Kr II and 324.569 nm Kr III, the most intensive transitions in the Kr II and Kr III spectra. Our Kr III transition probability values are the first data obtained experimentally using the RLIR method. A linear, low–pressure, pulsed arc operated in krypton discharge was used as …

Astrophysical Plasma Diagnostics Through Analysis Of Ar Iine Shape Characteristics, Vladimir Milosavljevic, Stevan Djenize

Articles

On the basis of five accurately recorded neutral argon ( ) line shapes (in the 4s-5p transition) we have recovered the basic plasma parameters i.e. electron temperature ( T) and electron density ( N) using our new line deconvolution procedure in the case of three different plasmas created in a linear, low-pressure, pulsed arc discharge. The mentioned plasma parameters have also been measured using independent experimental diagnostic techniques. An excellent agreement has been found among the two sets of obtained parameters. This recommends our deconvolution procedure for plasma diagnostic purposes, especially in astrophysics where direct measurements of the …

Experimental And Calculated Stark Widths Within The Kr I Spectrum, Vladimir Milosavljevic, Stevan Djenize, Milan S. Dimitrijevic

Articles

On the basis of the precisely recorded 20 neutral krypton (Kr I) line shapes (in the 5s−5p and 5s−6p transitions), we have obtained the basic plasma parameters, i.e., electron temperature (T) and electron density (N) using our line deconvolution procedure in a plasma created in a linear, low-pressure, pulsed arc discharge operated in krypton. The mentioned plasma parameters have also been measured using independent experimental diagnostics techniques. Agreement has been found among the two sets of the obtained parameters. This recommends our deconvolution procedure for plasma diagnostical purposes, especially in astrophysics where direct measurements of the …

Reply To "Comment On ‘Atomic Spectral Line Free-Parameter Deconvolution Procedure’”, Vladimir Milosavljevic, Goran Poparic

Articles

We do not agree with the authors of the preceding Comment [X. Nikolic, X. Ojurovic, and X. Mijatovic, Phys. Rev. E, 67, 058401, 2003]. Our numerical procedure for the deconvolution of the theoretical asymmetric convolution integral of a Gaussian and a plasma broadened spectral line profile jA,R(λ) for spectral lines enables the determination of all broadening parameters. All broadening parameters can be determined directly from the recorded line profile of a single line, with minimal assumptions or prior knowledge. Additional experimental diagnostics are not required.

The He I 706.52 Nm Line Shape Characteristics In The Plasma Diagnostics, Vladimir Milosavljevic, Stevan Djenize

Articles

On the basis of the precisely recorded 706.52 nm He I line shape we have obtained the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of five various plasmas created in a linear, low–pressure, pulsed arc discharge. Plasma parameters have been also measured using independent experimental diagnostical techniques. Excellent agreement was found among the two sets of the obtained parameters. This enables our deconvolution procedure to recommendation for plasma diagnostical purposes, especially in astrophysics where direct measurements of the plasma parameters (T and …

Ion Contribution To The Astrophysical Important 447.15, 587.56 And 667.82 Nm He I Spectral Lines Broadening, Vladimir Milosavljevic, Stevan Djenize

Articles

Characteristics of the astrophysical important Stark broadened 447.15 nm, 587.56 nm and 667.82 nm spectral line profiles have been measured at electron densities between 0.3 10 and 8.2 10 m and electron temperatures between 8000 and 33 000 K in plasmas created in five various discharge conditions using a linear, low-pressure, pulsed arc as an optically thin plasma source operated in a helium-nitrogen-oxygen gas mixture. On the basis of the observed asymmetry of the line profiles we have obtained their ion broadening parameters ( A) caused by influence of the ion microfield on the line broadening mechanism and also …

Stark Shifts And Transition Probabilities In The Ne Ii Spectrum, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic

Articles

Stark shifts (d) and transition probabilities of the spontaneous emission (Einstein's A values) of forty two singly charged neon ( ) ion spectral lines have been measured in a linear, low pressure, pulsed arc at 35 300 K electron temperature and 1.83 10 ²³ m ^-3 electron density. Transition probabilities have been obtained using the relative line intensity ratio (RLIR) method. Stark shift values have also been calculated, using the semiclassical perturbation formalism (SCPF). The measured and calculated shift values and the measured A values have been compared to the existing data taken from available data sources.

Temperature Dependence Of Stark Width Of The 463.054 Nm Nii Spectral Line, Vladimir Milosavljevic, Ruzica Konjevic, Stevan Djenize

Articles

Stark width of the 463.054 nm singly ionized nitrogen spectral line, that belong to transition, have been measured in a linear pulsed, low pressure, arc discharge. The working gas was helium-nitrogen-oxygen mixture. Electron densities of 0.7510²³ to 1.4510²³ were determined in the electron temperature range between 30000 K - 38000 K. The measured values have been compared with our calculated data, using the modified semiempirical approximation. On the basis of the agreement among experimental and theoretical Stark width data, the isolated 463.054 nm NII spectral line can be recommended as convenient spectral line for plasma diagnostics.

Measured Stark Widths And Shifts Of Several Niii Sectral Lines: Temperature Dependence, Stevan Djenize, Vladimir Milosavljevic

Articles

Stark parameters (width and shift) of four doubly ionized nitrogen spectral lines, that belong to 3s-3p and 3p-3d transitions (lower multiplets), have been measured in a linear pulsed, low pressure, arc discharge in the nitrogen-oxygen and helium-nitrogen-oxygen plasmas in a (30 000 - 54 000) K electron temperature and a (0.75 10²³ - 2.8 10²³) electron density ranges. The measured values have been compared to the existing experimental and calculated data.

On The Stark Broadening Parameters Of The Two Nii Spectral Lines Of The 3d-4f Transition, Vladimir Milosavljevic, Stevan Djenize

Articles

Stark parameters (width and shift) of two singly ionized nitrogen spectral lines, that belong to 3d-4f transition have been measured in a linear pulsed, low pressure, arc discharge in the nitrogen-oxygen plasma at a 54000 K electron temperature and at a 2.8×10 23 m−3 electron density. The measured values have been compared to the existing experimental and calculated data

Measured Stark Widths Of A 425,94 Nm Ari Spectral Line, Ljiljana Skuljan, Vladimir Milosavljevic, Aleksandar Sreckovic, Stevan Djenize

Articles

No abstract provided.