Laser induced collisions between Lithium isotopes (original) (raw)
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Collisional Ionization in Lithium Vapor Excited by Nanosecond Laser Pulses
Acta Physica Polonica A
We report a theoretical study of the collisional ionization processes which occur under 2s → 2p excitation of lithium vapor excited with a nanosecond pulsed laser. The time evolution of the electron energy distribution function and the atomic ion density (Li +) as well as the molecular ion density (Li + 2) at dierent lithium vapor densities was investigated. The results show a nonlinear behavior of the energy spectra of the electrons created during the interaction of the laser with the lithium vapor. The nonlinear behavior results from superelastic collisions between the free electrons produced by collisional ionization and photoionization with Li(2p). The results also show that a competition exists between the collisional ionization and photoionization processes in producing the atomic ion and the molecular ions.
Selective laser excitation in lithium
2007
Following a number of initial experiments using tunable diode laser selective excitation of lithium isotopes, published in the 1998-2003 period, there has been renewed and increased activity in the field. Here, a brief review of the selective laser excitation of Li isotopes is given. Emphasis is on the spectroscopy and requirements for laser isotope separation in Li. Also, the recent literature is briefly surveyed. Received 2007/06/30; revised 2007/07/03; published 2007/07/05 ©Optics Journal (2007) ISSN: 1936-9808 Principles and requirements for laser isotope separation of heavy ions are discussed by Paisner and Solarz [1] in the book Laser Spectroscopy and its Applications. This article refers to the use of copper-laser-pumped dye lasers. The theory, construction details, and multiple-prism grating configurations, of narrow-linewidth copper-vapor-laser (CVL) pumped dye lasers are discussed in detail by Duarte and Piper [2, 3]. Additional tunable lasers that are useful for laser iso...
Lithium Ionization by a Strong Laser Field
Physical Review Letters, 2005
We study ab initio computations of the interaction of Lithium with a strong laser field. Numerical solutions of the time-dependent fully-correlated three-particle Schroedinger equation restricted to the one-dimensional soft-core approximation are presented. Our results show a clear transition from non-sequential to sequential double ionization for increasing intensities. Non sequential double ionization is found to be sensitive to the spin configuration of the ionized pair. This asymmetry, also found in experiments of photoionization of Li with synchrotron radiation, shows the evidence of the influence of the exclusion principle in the underlying rescattering mechanism.
The spectra of the 2s -2p lithium transitions were studied in an atomic-lithium vapor-argon-gas mixture by a Doppler-free saturation amplitude modulation spectroscopy technique that employs a tunable diode laser. Lamb-dip and crossover signals were highly resolved. The experimental Doppler-free spectra were used in conjunction with a density matrix method to yield parameters of spectroscopic interest. These parameters include line broadening and relaxation rates that are due to collisions between isotopic species and argon atoms. In addition, Doppler-limited spectra were used to determine density, concentration, and temperature of the lithium isotopes.
Ionization of lithium vapor by nanosecond resonant laser pulses tuned to 2S → 2P transition
Indian Journal of Physics, 2014
A theoretical study is reported for the resonant excitation and ionization of dense lithium vapor induced by nanosecond laser pulses, tuned to the resonance transition 2S-2P. The lithium vapor with density (10 14-10 16 cm-3) is assumed to be excited and ionized by a laser beam with laser power of (10 5-10 6 W cm-2) according to the experimental conditions of Skenderovic et al. (Phys Rev A 62:052707, 2000). The time evolution of electron energy distribution function and the electron density, the population density of the excited states as well as the atomic ion, are solved numerically. The numerical calculations of the electron energy distribution function show that nonequilibrium plasmas are produced in lithium vapor by laser irradiation of the nS-nP resonance line. The electrons in these plasmas are heated by superelastic collisions with atoms in the nP state giving a distribution of electrons in energy that is characterized by a series of spikes at energy separated by the nS-nP transition energy. In addition, the competition between photoionization processes and collisional ionization processes for producing the Li ? as well as energy pooling collisions process of the excited lithium atoms plays essential roles in populating the highly excited states. Moreover, the results are found to be consistent with the experimental observations.
Atomic Lithium Excitation by Electron Impact
Journal of Kufa-Physics
Alkaline group elements such as lithium are of great interest in astrophysics as well as in diagnosing the plasma. A lot of lines which appears in lithium spectrum had been identified in the solar spectrum [1].
Ionizing Collisions of Laser-Excited Rare Gas Atoms
Journal de physique. Colloque, 1985
Resume : Nous avons utilise la spectrometrie de masse et la spectrometrie d'electrons pour Ctudier l'ionisation d'atomes d'argon et de krypton dans des collisions, aux energies thermiques, avec des atomes de Ne B courte duree de vie (2p53p, J = 1,2,3) excites par laser. Les sections efficaces dependent fortement de l'dtat excite ; leur comportement est bien reproduit par des calculs fondes sur les courbes theoriques d'energie potentielle et sur l'existence d'un seul etat autoionisant B decroissance exponentielle. Les rendements total et partiel d'ions et les spectres d'electrons presentent des effets de polarisation imporfants ; on ne peut les expliquer que par des probabilites d'autoionisation dQpendant de 0 et favorisant le transfert df61ectrons CI-> o.
Resonance Ionization Spectroscopy in a Thermal Lithium Beam by Means of Diode Lasers
Applied Optics, 1999
We measured two-step photoion current spectra by using a semiconductor laser and a Q-switched Nd:YAG laser with fourth-harmonic generation in an atomic lithium beam. The number of ions measured was compared with an estimate from the diode laser absorption measurement that uses a set of precisely solved rate equations. We explain the saturation effects on absorption by using transit time relaxation and detailed calculations of the ionization levels.