Doppler broadening

About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.

A spectroscopic investigation of the near-cathode regions in a low-pressure arc

Abstract: The investigation described in this paper dealt with spectroscopic measurements of the near-cathode plasma in a low-pressure arc on a Mg cathode with a current of 100 A and a pulse of duration s. Information on the directed velocities of the heavy particles (ions and neutral species) has been obtained from measuring the Doppler shift and the broadening of the spectral lines. The electron density in the cathode flare has been estimated from the collisional broadening of the lines. The experimental data obtained support the validity of the potential hump model for treating the mechanism of fast-ion generation.

Theory of Atomic Hyperfine Structure

Abstract: Publisher Summary This chapter discusses the principal experimental techniques in the study of hyperfine interactions, such as the Hamiltonian for hyperfine interactions; hyperfine structure of one-electron atoms; and hyperfine structure of complex atoms and ions The classical method is optical spectroscopy Resolution of hyperfine structure in optical spectra has been improved significantly by the use of interferometers, such as the Fabry-Perot etalon, in place of diffraction gratings Splittings as small as 0005 cm-1 (∼ 100 Mc/sec) could theoretically be resolved by an interference spectrograph In practice, however, atoms in the gas phase have linewidths determined by the Doppler effect, which are typically of the order of 01 cm-1 for light atoms to 001 cm-' for heavy atoms Use of atomic beams, in which Doppler broadening is eliminated by observing atoms perpendicular to their line of flight, is required for the measurements of splittings finer than 001 cm-1 The most successful technique for the study of atomic hfs has been atomic beam magnetic resonance Paramagnetic resonance of atoms in the gas phase3 and in inert matrices and of transition metal ions in solution and in crystals has also yielded useful data on hyperfine interactions It must, however, be recognized that external interactions usually influence the observed hyperfine structure The chapter mentions the optical polarization spin-exchange technique

Analysis of stimulated Raman scattering in cw kW fiber oscillators

Abstract: In this paper the threshold for Stimulated Raman scattering (SRS) is analyzed experimentally and theoretically for monolithic LMA cq kW fiber oscillators. Four oscillators with different spectral widths of the low reflecting (LR) Fiber Bragg Gratings (FBG) (0.04 nm, 0.5 nm, 1.5 nm (FWHM) and without LR grating) were characterized. Experimental it was found that threshold of SRS depends on the spectral width of the out coupling FBGs, which is not yet understood completely. Attempts to describe such lasers by simulations are based on nonlinear Schrodinger equation supporting spectral broadening of cw-fiber laser, rate equation gain as well as broadband Raman gain. The experimental results and the simulations were compared and discussed.

Fabry–Perot interferometry for magnetron plasma temperature diagnostics

Abstract: A confocal Fabry–Perot interferometer was utilized to study Ar–Ti, Ar–Cu and Ar–Cr dc magnetron discharges during sputtering of the corresponding metallic targets. Doppler broadening of Ar and Ti emission lines was measured in the wide range of Ar pressures and at different powers applied to the discharge. Spatial characterization of Ar and Ti line broadening through the discharge volume was also performed. Corresponding temperatures of Ar and thermalized Ti atoms were determined by Doppler broadening of the corresponding emission lines. Results show that the Ar temperature depends mainly on the working pressure in the reactor and it was found to be on average in the range 700–1300 K for the working pressure range 2–240 mTorr. The temperature of Ti was found to be about 600–800 K; it slightly increases with increasing applied power and does not depend on the working pressure in the reactor. Ar temperature measurements were verified by adding nitrogen in the discharge and by the measuring of the N2(C, v' = 0 − B, v'' = 2) vibrational band shape.