MEASUREMENT OF ATOMIC CONCENTRATIONS IN REACTING FLOWS THROUGH THE USE OF STIMULATED GAIN OR LOSS

摘要

A pump laser at 226 nm was used to generate a population inversion between the 3p P-3(2) and 3s S-3(1) states of the oxygen atom in the postflame gases of a 7-torr H-2/O-2 flame by means of resonant two-photon absorption from the ground state. The inversion produced an amplified spontaneous emission (ASE) signal at 845 nm. A probe laser tuned to this transition was crossed at a small angle with the pump beam. The probe beam experienced gain at the expense of the ASE signal. By analyzing the gain on the probe beam and the loss on the ASE signal, we have determined the density of oxygen atoms in the flame environment. [References: 19]