Detection of OH in the atmosphere using a dye laser

Abstract

Preliminary experiments suggesting the feasibility of using a resonance fluorescence scheme to detect ambient concentrations of OH in the atmosphere (10⁶ molecules/cm³) were carried out using OH concentrations near 10¹² molecules/cm³. The $P_1^{\text{(1)}}$ line of the v = 0 → 1 branch of the lowest electronic transition of OH at 2822 Å was resonantly excited with radiation from a doubled dye laser. The subsequent fluorescence from the v = 0 → 0 branch with Δν ≅ 3050 cm⁻¹ was observed to have a fluorescence efficiency of 0.6 × 10⁻³ in N₂ at atmospheric pressure with a 10‐mm partial pressure of H₂O. This fluorescence occurs 500 cm⁻¹ away from any strong Raman line in the atmosphere.