scholarly journals Investigations of Laser Produced Plasmas Generated by Laser Ablation on Geomaterials. Experimental and Theoretical Aspects

Symmetry ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1391 ◽  
Author(s):  
Enescu ◽  
Irimiciuc ◽  
Cimpoesu ◽  
Bedelean ◽  
Bulai ◽  
...  
Keyword(s):  
Morphological Structure ◽  
Optical Emission ◽  
Ionic Species ◽  
Plasma Parameters ◽  
Mineral Contents ◽  
Plasma Dynamics ◽  
Time Resolved ◽  
Type Group ◽  
Group Invariance ◽  
Ablation Plasma

Several surface investigation techniques, such as X-ray diffraction (XRD), EDX, and optical microscopy, were employed in order to describe the mineral contents in several geomaterials. Space and time resolved optical emission spectroscopy was implemented to analyze the plasma generated by the laser–geomaterial interaction. The values of the plasma parameters (velocity and temperature) were discussed with respect to the nature of the minerals composing the geomaterials and the morphological structure of the samples. Correlations were found between the excitation temperatures of the atomic and ionic species of the plasmas and the presence of calcite in the samples. A mathematical model was built to describe the dynamics in ablation plasma using various mathematical operational procedures: multi structuring of the ablation plasma by means of the fractal analysis and synchronizations of the ablation plasma entities through SL (2R) type group invariance and in a particular case, through self-modulation in the form of Stoler type transformations. Since Stoler type transformations are implied in general, in the charge creation and annihilation processes, then the SL (2R) type group invariance become fundamental in the description of ablation plasma dynamics.

ZnCdO/ZnMgO and ZnO/AlGaN Heterostructures for UV and Visible Light Emitters

2005 ◽  
Vol 892 ◽  
Author(s):  
Andrei Osinsky ◽  
Jianwei Dong ◽  
J. Q. Xie ◽  
B. Hertog ◽  
A. M. Dabiran ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Compositional Analysis ◽  
Optical Emission ◽  
Rf Plasma ◽  
Light Emitters ◽  
Time Resolved ◽  
Light Emitting ◽  
Spatially Resolved ◽  
Time Resolved Photoluminescence ◽  
Made In

AbstractThis paper reviews of some of the progress made in the development of ZnO-based light emitting diodes (LEDs). n-ZnO/p-AlGaN-based heterostructures have been successfully for the fabrication of UV emitting LEDs that have operated at temperatures up to 650K, suggesting an excitonic origin for the optical transitions. RF-plasma-assisted molecular beam epitaxy has been used to grow epitaxial CdxZn1-xO films on GaN/sapphire structure. These films have a single-crystal wurtzite structure as demonstrated by structural and compositional analysis. High quality CdxZn1-xO films were grown with up to x=0.78 mole fraction as determined by RBS and SIMS techniques. Optical emission ranging from purple (Cd0.05Zn0.95O) to yellow (Cd0.29Zn0.71O) was observed. Compositional fluctuations in a Cd0.16Zn0.84O films were not detected by spatially resolved CL measurements, although intensity fluctuation with features of ∼0.5 μm diameter were seen on the intensity maps. Time resolved photoluminescence shows multi-exponential decay with 21 psec. and 49±3 psec. lifetimes, suggesting that composition micro-fluctuations may be present in Cd0.16Zn0.84O film.

scholarly journals Dry Etching Performance and Gas-Phase Parameters of C6F12O + Ar Plasma in Comparison with CF4 + Ar

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1595
Author(s):  
Nomin Lim ◽  
Yeon Sik Choi ◽  
Alexander Efremov ◽  
Kwang-Ho Kwon
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Reactive Ion Etching ◽  
Research Work ◽  
Optical Emission ◽  
Plasma Parameters ◽  
Ion Etching ◽  
Ar Plasma ◽  
Ar Gas ◽  
Etching Selectivity

This research work deals with the comparative study of C6F12O + Ar and CF4 + Ar gas chemistries in respect to Si and SiO2 reactive-ion etching processes in a low power regime. Despite uncertain applicability of C6F12O as the fluorine-containing etchant gas, it is interesting because of the liquid (at room temperature) nature and weaker environmental impact (lower global warming potential). The combination of several experimental techniques (double Langmuir probe, optical emission spectroscopy, X-ray photoelectron spectroscopy) allowed one (a) to compare performances of given gas systems in respect to the reactive-ion etching of Si and SiO2; and (b) to associate the features of corresponding etching kinetics with those for gas-phase plasma parameters. It was found that both gas systems exhibit (a) similar changes in ion energy flux and F atom flux with variations on input RF power and gas pressure; (b) quite close polymerization abilities; and (c) identical behaviors of Si and SiO2 etching rates, as determined by the neutral-flux-limited regime of ion-assisted chemical reaction. Principal features of C6F12O + Ar plasma are only lower absolute etching rates (mainly due to the lower density and flux of F atoms) as well as some limitations in SiO2/Si etching selectivity.

Optical, electrochemical and third-order nonlinear optical studies of triphenylamine substituted zinc phthalocyanine

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1173-1181 ◽  
Author(s):  
Narra Vamsi Krishna ◽  
Puliparambil Thilakan Anusha ◽  
S. Venugopal Rao ◽  
L. Giribabu
Keyword(s):  
Nonlinear Optical ◽  
Emission Spectra ◽  
Optical Emission ◽  
Soret Band ◽  
Laser Pulses ◽  
Zinc Phthalocyanine ◽  
Third Order ◽  
Time Resolved ◽  
Nlo Properties ◽  
Scan Data

Zinc phthalocyanine possessing triphenylamine at its peripheral position has been synthesized and its optical, emission, electrochemical and third-order nonlinear optical (NLO) properties were investigated. Soret band was broadened due to the presence of triphenylamine moiety. Electrochemical properties indicated that both oxidation and reduction processes were ring centered. Emission spectra were recorded in different solvents and the fluorescence yields obtained were in the range of 0.02–0.17 while the time-resolved fluorescence data revealed radiative lifetimes of typically few ns. Third-order NLO properties of this molecule have been examined using the Z-scan technique with picosecond (ps) and femtoseocnd (fs) pulses. Closed and open aperture Z-scan data were recorded with 2 ps/1 50 fs laser pulses at a wavelength of 800 nm and NLO coefficients were extracted from both the data. Our data clearly suggests the potential of this molecule for photonics applications.

Langevin approach to plasma kinetics with Coulomb collisions

1999 ◽  
Vol 61 (1) ◽  
pp. 89-106 ◽  
Author(s):  
M. G. CADJAN ◽  
M. F. IVANOV
Keyword(s):  
Laser Pulses ◽  
Intense Laser ◽  
Plasma Parameters ◽  
Plasma Dynamics ◽  
Coulomb Collisions ◽  
Numerical Tests ◽  
Langevin Approach ◽  
Intense Laser Radiation ◽  
Overdense Plasma ◽  
Kinetics Of

The Langevin approach to the kinetics of a collisional plasma is developed. Some collision models are considered, and the corresponding stochastic differential equations are derived. These equations can be regarded as an alternative to the description of a plasma in terms of a distribution function. The method developed here allows one to simulate plasma processes, taking account of both collective kinetics effects and Coulomb collisions. Results of the numerical simulation of the intervention of laser pulses with an overdense plasma are presented. The dependence of the absorption coefficient on the plasma parameters is calculated. The features of the plasma dynamics under the action of intense laser radiation are observed and discussed. The results of numerical tests of the validity of this method are also presented.

scholarly journals Time-Resolved Quadrupole Mass Spectrometric Studies on Pulsed Laser Ablation of TiO2

1999 ◽  
Vol 18 (3) ◽  
pp. 99-109 ◽  
Author(s):  
Yongxin Tang ◽  
Zhenhui Han ◽  
Qizong Qin
Keyword(s):  
Laser Ablation ◽  
Continuous Wave ◽  
Center Of Mass ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Ionic Species ◽  
Mass Spectrometric ◽  
Quadrupole Mass ◽  
Time Resolved ◽  
Ambient Oxygen

Pulsed laser ablation of TiO2 at 355 nm and 532 nm has been investigated using an angleand time-resolved quadrupole mass spectrometric technique. The major ablated species include O (m/e = 16), O2 (m/e = 32), Ti (m/e = 48), TiO (m/e = 64) and TiO2 (m/e = 80). The time-of-flight (TOF) spectra of ablated species are measured for the ionic and neutral ablated species, and they can be fitted by a Maxwell – Boltzmann (M – B) distribution with a center-of-mass velocity. The measured angular distributions of the ionic species (O+ and Ti+) and the neutral species (O and Ti) can be fitted with cos⁡nθ and a cos⁡θ + (1−a)cos⁡nθ, respectively. In addition, a continuous wave oxygen molecular beam is introduced into the ablated plume, and the enhancement of the signal intensities of TiO is observed. It implies that the ablated Ti atoms/ions species can react with ambient oxygen molecules in the gas phase. In the meanwhile, the physicochemical mechanism of pulsed laser ablation of TiO2 is discussed.

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