Chapter 9 - EXCITED SPECIES

Abstract

This chapter discusses the excited atomic and molecular species within the discharge because it is these species that are critical to the determination of light output for lamps or optical gain and available power for lasers. The description of the electrons is a necessary prerequisite to the study of excited species because electron impact excitation is either the primary or secondary source of excitation of the excited species. To determine the density of the excited species of interest, either on a steady state or time varying basis, it is necessary to evaluate the production and loss mechanisms. The excited species can be produced by electron impact excitation from ground or lower excited species, by collisional energy exchange with excited atoms or molecules, or by radiative cascade from higher excited species. The excited species density can be determined by evaluating the loss processes. There are two distinct cases: (1) when radiative decay dominates and (2) when collisional decay dominates.