Abstract

The visible emission spectrum of the water cation, H₂O⁺, is a prominent feature in comet tails, and is often observed in laboratory discharges. However, until now the visible electronic spectrum has never been observed in absorption. We have used a tunable ring dye laser and a velocity-modulated discharge to detect the${\tilde{\text{A}}}^2{\tilde{\text{A}}}_1-{\tilde{\text{X}}}^2{\tilde{\text{B}}}_1$ visible electronic spectrum in absorption, in H₂O⁺ and D₂O⁺.

© 1992 Optical Society of America