Sensitive detection of CO by tunable VUV laser excitation of the B 1Σ + state

Abstract

Rotational state selective resonantly enhanced two photon ionization of CO has been investigated. Tunable vacuum ultraviolet (VUV) laser radiation was used to excite the molecules in the (B 1Σ +, υ′ = 0, 1 ← X 1Σ +, υ″ = 0) transition. Ionization of the excited molecules was done by the fundamental of the VUV radiation. A weak predissociation is observed in the high J' levels of B 1Σ +, υ' = 1. Sensitivity measurements show that this technique is capable of detecting CO concentrations as low as 1.5 x 10 -11 mbar in a single rotational state.