On Atomic Lifetimes and Environmental Density

Abstract

Atomic lifetime measurements span a wide range, from attoseconds to years. The frontier of exploratory lifetime measurements, presently, is in the long part of the above time range, with an eye on astrophysical problems. In a combination of review paper, tutorial, and Editorial, the physical environments and experiments are discussed, in which the results of such lifetime measurements matter. Although accurate lifetime measurement results are important for our understanding of atomic structure and dynamics, and for the diagnostics of various plasma environments, the order of magnitude is often precise enough to see why time resolution may be of interest in an experiment, from laser-produced plasmas of high densities to planetary nebulae of very low densities.

Lifetime measurement of the 3d9 2D3/2 metastable level in Mo15+ at an electron beam ion trap

“…Forbidden transitions have been captive substantial interest across various fields. [1][2][3][4] Precision measurements of forbidden transitions have multiple applications, including probing fundamental physics, [5][6][7][8][9][10] developing frequency-standard metrology, [11][12][13][14] and searching for new physics beyond the standard models. [15] Moreover, these forbidden lines contribute significantly to diagnosing laboratory and astrophysical plasmas, [1,[16][17][18][19][20] since their intensities tend to be sensitive to the density or temperature of the plasma.…”