title: Multiphoton excitation ionization of N(2) following collisional energy transfer with H(2)O: a potential measure of molecular mixing.
abstract: A multiphoton ionization excitation of N(2) following collisional energy exchange with optically excited H(2) O was demonstrated, and its potential for measuring H(2) O-N(2) mixing at the molecular level was evaluated. In this process, N(2) is sensitized by a collisional energy exchange with H(2)O molecules excited by a tunable KrF laser. The sensitized N(2) molecules are further excited and ionized by two additional photons of the same laser pulse. Independent images of sensitized N2(+) emission at 391.4 nm and by OH at 308 nm formed by the dissociation of excited H(2)O were obtained along a laser beam traversing slow dry-air and N(2) jets entering room air. Although effects of O(2) and N(2) collisional quenching were noted, such images can potentially be used to measure H(2)O-N(2) molecular mixing and the concentration of H(2)O independently. The detection of H(2)O nucleation by this technique suggests that imaging of H(2)O droplet evaporation or visualizing and monitoring H(2)O condensation may also be possible.
authors.forename: G
authors.initials: G
authors.lastname: Laufer
authors.forename: A S
authors.initials: AS
authors.lastname: Lee
authors.forename: H K
authors.initials: HK
authors.lastname: Chelliah