Gas ionization by focused laser beams

1984 ◽  
Vol 62 (10) ◽  
pp. 1010-1013 ◽  
Author(s):  
A. L. de Brito
Keyword(s):  
Laser Radiation ◽  
Photon Energy ◽  
Ionization Energy ◽  
Laser Beams ◽  
Line Broadening ◽  
Gas Ionization ◽  
The Mean ◽  
Gas Molecules ◽  
Focused Laser Beams

It is shown that the effect of line broadening by focusing may contribute considerably to the observed laser-induced ionization of gases even when the ionization energy of the gas molecules is well above the mean photon energy of the laser radiation.

Comments on: Line broadening by focusing; Gas ionization by focused laser beams

1985 ◽  
Vol 63 (7) ◽  
pp. 1013-1013
Author(s):  
F. L. Curzon
Keyword(s):  
Laser Beam ◽  
Frequency Spectrum ◽  
Laser Beams ◽  
Line Broadening ◽  
Gas Ionization ◽  
On Line ◽  
Normal Lens ◽  
Focused Laser Beams

It is pointed out that the frequency spectrum of a laser beam is not broadened when the beam is focused by a normal lens. This assertion contradicts the conclusion reached by the authors of the articles cited in the title above.

Reply to comments on: Line broadening by focusing; Gas ionization by focused laser beams

1985 ◽  
Vol 63 (7) ◽  
pp. 1014-1014
Author(s):  
Arthur Jabs
Keyword(s):  
Laser Beams ◽  
Line Broadening ◽  
Gas Ionization ◽  
On Line ◽  
Focused Laser Beams

scholarly journals The Collision Broadening of Spectral Lines

1968 ◽  
Vol 21 (1) ◽  
pp. 13 ◽  
Author(s):  
RW Parsons ◽  
VI Metchnik ◽  
RJ Dyne
Keyword(s):  
Collision Cross Section ◽  
Hard Spheres ◽  
Spectral Lines ◽  
Line Broadening ◽  
Collision Broadening ◽  
The Mean ◽  
Gas Molecules ◽  
Collision Processes ◽  
Half Power ◽  
Van Vleck

The shape of a collision-broadened spectral line depends on the assumptions made about the collision processes involved. If the collision cross section varies inversely as the relative speed of the colliding molecules, the half-width to the half-power points and to the points of steepest slope should be 1/27T1' and 1/(2";3)7T1' respectively, where l' is the mean interval between line-broadening collisions. It is shown that, in a gas of "hard-sphere" molecules, the shape of the line is modified and the above half-widths are reduced by' 6�4 and 9�7% respectively. While it is not suggested that gas molecules behave entirely as hard spheres, it is suggested that some deviations from the Van Vleck-Weisskopf-Lorentz shape may occur, and that it may be possible to detect these deviations experimentally

Line broadening by focusing

1984 ◽  
Vol 62 (7) ◽  
pp. 661-668 ◽  
Author(s):  
Adelsindo Liberato de Brito ◽  
Arthur Jabs
Keyword(s):  
Light Beam ◽  
Ad Hoc ◽  
Incident Light ◽  
Wave Theory ◽  
Spectral Width ◽  
Line Broadening ◽  
Classical Wave ◽  
Gas Ionization ◽  
The Mean ◽  
Quantitative Formula

We point out that the spectral width of a quasimonochromatic light beam broadens when the beam is focused. A quantitative formula for this broadening is derived from classical wave theory. The effect is shown to explain some experiments on laser beams done by Panarella which he explained using the ad hoc hypothesis that the frequency of the photons changes along with the intensity of the light beam. The line broadening by focusing might also contribute to gas ionization by incident light when the ionization potential is well above the mean photon energy. Remarks are made on some direct applications of the Heisenberg relations in comparison with our treatment.

Excitation of transitions between atomic or molecular energy levels by monochromatic laser radiation - II. Excitation under conditions of strictly inhomogeneous line broadening and mixed homogeneous and inhomogeneous broadening

1978 ◽  
Vol 362 (1708) ◽  
pp. 13-25 ◽  
Keyword(s):  
Laser Radiation ◽  
Line Width ◽  
Energy Levels ◽  
Incident Radiation ◽  
Exciting Radiation ◽  
Half Line ◽  
Line Broadening ◽  
Moment Matrix ◽  
Inhomogeneous Line Broadening ◽  
Inhomogeneous Line

The development with time of the excitation of a transition between two atomic or molecular energy levels under the influence of monochromatic laser radiation is examined under conditions of strictly inhomogeneous line broadening due to such causes as doppler shift arising from translational velocity. The ratio of the number of molecules, N 2 , in an excited state to the total number, N , is calculated for various ratios of the intensity parameter β ═ E 0 μ / ħ to the half line-width ∆ , where E 0 is the amplitude of the electric field in the incident radiation and is the dipole moment matrix element for the transition. Excitation functions obtained in a previous paper (I) for various values of the ratio γ/β , where γ is the half line-width in the absence of inhomo­geneous broadening, are used to obtain the variation of N 2 / N with time under conditions of mixed broadening for various values of the ratio γ/∆ and γ/β , when the exciting radiation is in exact resonance with the central frequency of the transition.

scholarly journals Controlling the carrier-envelope phase of few-cycle focused laser beams with a dispersive beam expander

2008 ◽  
Vol 16 (26) ◽  
pp. 22090 ◽  
Author(s):  
Carlos J. Zapata-Rodríguez ◽  
Miguel A. Porras
Keyword(s):  
Laser Beams ◽  
Carrier Envelope Phase ◽  
Beam Expander ◽  
Focused Laser Beams

The Use of the Pseudo-Voigt Function in the Variance Method of X-ray Line-Broadening Analysis

1997 ◽  
Vol 30 (4) ◽  
pp. 427-430 ◽  
Author(s):  
F. Sánchez-Bajo ◽  
F. L. Cumbrera
Keyword(s):  
Crystallite Size ◽  
Original Form ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Variance Method ◽  
The Mean ◽  
Voigt Function

A modified application of the variance method, using the pseudo-Voigt function as a good approximation to the X-ray diffraction profiles, is proposed in order to obtain microstructural quantities such as the mean crystallite size and root-mean-square (r.m.s.) strain. Whereas the variance method in its original form is applicable only to well separated reflections, this technique can be employed in the cases where there is line-profile overlap. Determination of the mean crystallite size and r.m.s. strain for several crystallographic directions in a nanocrystalline cubic sample of 9-YSZ (yttria-stabilized zirconia) has been performed by means of this procedure.

scholarly journals Single particle scattering with focused laser beams

1977 ◽  
Vol 16 (4) ◽  
pp. 1104 ◽  
Author(s):  
Lee W. Casperson ◽  
C. Yeh ◽  
Wing F. Yeung
Keyword(s):  
Single Particle ◽  
Laser Beams ◽  
Particle Scattering ◽  
Focused Laser Beams
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