Mecanismos de excitación de la emisión láser en un plasma de xenón multiplemente ionizado

El objetivo del trabajo fue estudiar los mecanismos de excitación del plasma de xenón y de las características de la emisión producida en la región UV-visible, tanto espontánea como láser. Para ello se hizo uso de la espectroscopia resuelta en tiempo, espectroscospía atómica convencional y de modelos teóricos para analizar su funcionamiento.Tesis digitalizada en SEDICI gracias a la Biblioteca de Física de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Mecanismos de excitación de la emisión láser en un plasma de xenón multiplemente ionizado

El objetivo del trabajo fue estudiar los mecanismos de excitación del plasma de xenón y de las características de la emisión producida en la región UV-visible, tanto espontánea como láser. Para ello se hizo uso de la espectroscopia resuelta en tiempo, espectroscospía atómica convencional y de modelos teóricos para analizar su funcionamiento.Tesis digitalizada en SEDICI gracias a la Biblioteca de Física de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Excitation Mechanisms and Characterization of a Multi-Ionic Xenon Laser

The emission characteristics of an ultraviolet-visible pulsed multi-ionic xenon laser were studied through time-resolved spectroscopy and the results were interpreted using a collisional radiative theoretical model. This analysis includes more than 20 laser lines belonging to several ionic species (Xe III VIII). Depending on the experimental conditions, different temporal distributions of the laser lines and their corresponding sponta neous emissions can be observed. In particular, laser emission presents temporal oscillations near threshold. Pumping processes for the laser transitions have been analyzed by using this model. Relativistic Hartree Fock calculations of laser level lifetimes and radiative transition probabilities were performed. Experimental laser gain for several transitions were obtained and compared with the theoretical values derived from the calculations.Facultad de Ingenierí

Excitation Mechanisms and Characterization of a Multi-Ionic Xenon Laser

The emission characteristics of an ultraviolet-visible pulsed multi-ionic xenon laser were studied through time-resolved spectroscopy and the results were interpreted using a collisional radiative theoretical model. This analysis includes more than 20 laser lines belonging to several ionic species (Xe III VIII). Depending on the experimental conditions, different temporal distributions of the laser lines and their corresponding sponta neous emissions can be observed. In particular, laser emission presents temporal oscillations near threshold. Pumping processes for the laser transitions have been analyzed by using this model. Relativistic Hartree Fock calculations of laser level lifetimes and radiative transition probabilities were performed. Experimental laser gain for several transitions were obtained and compared with the theoretical values derived from the calculations.Facultad de Ingenierí

Revised and extended analysis in four times ionized xenon Xe V

The atomic-emission spectrum of four times ionized xenon (Xe V) has been observed in the region 500–6700 Å; 233 lines were classified as transition between 5s5p3, 5s25p5d, 5s25p6s with 5s25p2, 5s25p6p and 5s25p4f configurations. Ninty-seven of these lines are reported for the first time. Two new energy level values corresponding to the 5s25p4f configuration have been determined, and we proposed two new values for the previously reported 3D1 and 3G5 energy levels of this configuration. The value of the 5s25p6p 1S0 energy level has also been determined, and we propose a new value for the previously reported 5s25p5d 3F4 energy level. New adjusted values for the previously known levels of the studied configurations are included. Least-squares fitted parametric calculations involving configuration interactions have been carried out to interpret the observed spectrum.Facultad de Ciencias ExactasCentro de Investigaciones Óptica

Revised and extended analysis in four times ionized xenon Xe V

The atomic-emission spectrum of four times ionized xenon (Xe V) has been observed in the region 500–6700 Å; 233 lines were classified as transition between 5s5p3, 5s25p5d, 5s25p6s with 5s25p2, 5s25p6p and 5s25p4f configurations. Ninty-seven of these lines are reported for the first time. Two new energy level values corresponding to the 5s25p4f configuration have been determined, and we proposed two new values for the previously reported 3D1 and 3G5 energy levels of this configuration. The value of the 5s25p6p 1S0 energy level has also been determined, and we propose a new value for the previously reported 5s25p5d 3F4 energy level. New adjusted values for the previously known levels of the studied configurations are included. Least-squares fitted parametric calculations involving configuration interactions have been carried out to interpret the observed spectrum.Facultad de Ciencias ExactasCentro de Investigaciones Óptica

Excitation Mechanisms and Characterization of a Multi-Ionic Xenon Laser

The emission characteristics of an ultraviolet-visible pulsed multi-ionic xenon laser were studied through time-resolved spectroscopy and the results were interpreted using a collisional radiative theoretical model. This analysis includes more than 20 laser lines belonging to several ionic species (Xe III VIII). Depending on the experimental conditions, different temporal distributions of the laser lines and their corresponding sponta neous emissions can be observed. In particular, laser emission presents temporal oscillations near threshold. Pumping processes for the laser transitions have been analyzed by using this model. Relativistic Hartree Fock calculations of laser level lifetimes and radiative transition probabilities were performed. Experimental laser gain for several transitions were obtained and compared with the theoretical values derived from the calculations.Facultad de Ingenierí

Evaluation of self-absorption of manganese emission lines in laser induced breakdown spectroscopy measurements

This paper is part o f a more general study aimed to the determination o f the best experimental procedures for reliable quantitative measurements o f F e-M n alloys by LIBS. In this work, attention is pointed on the self-absorption processes, whose effect deeply influences the LIBS measurements, reflecting in non-linear calibration curves. The effect o f self-absorption on the line intensity can be quantified by defining a self absorption coefficient, that measures the deviation o f the line intensity from the linear extrapolation o f the curve o f growth in the optically thin regime. The authors demonstrated in a previous paper that self absorption coefficients could be calculated once the electron density o f the plasma is known and the Stark coefficients o f the lines are available. However, when the Stark coefficients o f the lines o f interest are not known, a different approach is needed. In this work a new method for evaluation o f self absorption coefficients in LIBS measurements is presented, which does not require the knowledge o f Stark coefficients. In order to understand the basic principles and setting out the theoretical tools that w ill be used for the analysis o f the alloys, a preliminary study was done on pure Mn; LIBS spectra were acquired in different experimental conditions, at different laser energies and different delays after the laser irradiation o f the sample. Moreover, collinear double pulse measurements were also performed. Analytical relations were derived and experimental procedures devised for evaluation o f the self absorption coefficients o f several Mn lines, which are important for characterization and control o f the experimental conditions in which the analysis is performed.Facultad de Ingenierí

Evaluation of self-absorption of manganese emission lines in laser induced breakdown spectroscopy measurements

This paper is part o f a more general study aimed to the determination o f the best experimental procedures for reliable quantitative measurements o f F e-M n alloys by LIBS. In this work, attention is pointed on the self-absorption processes, whose effect deeply influences the LIBS measurements, reflecting in non-linear calibration curves. The effect o f self-absorption on the line intensity can be quantified by defining a self absorption coefficient, that measures the deviation o f the line intensity from the linear extrapolation o f the curve o f growth in the optically thin regime. The authors demonstrated in a previous paper that self absorption coefficients could be calculated once the electron density o f the plasma is known and the Stark coefficients o f the lines are available. However, when the Stark coefficients o f the lines o f interest are not known, a different approach is needed. In this work a new method for evaluation o f self absorption coefficients in LIBS measurements is presented, which does not require the knowledge o f Stark coefficients. In order to understand the basic principles and setting out the theoretical tools that w ill be used for the analysis o f the alloys, a preliminary study was done on pure Mn; LIBS spectra were acquired in different experimental conditions, at different laser energies and different delays after the laser irradiation o f the sample. Moreover, collinear double pulse measurements were also performed. Analytical relations were derived and experimental procedures devised for evaluation o f the self absorption coefficients o f several Mn lines, which are important for characterization and control o f the experimental conditions in which the analysis is performed.Facultad de Ingenierí