Production of ozone and nitrogen oxides by laser filamentation

Abstract

We have experimentally measured that laser filaments in air generate up to 1014, 3×1012, and 3×1013 molecules of O3, NO, and NO2, respectively. The corresponding local concentrations in the filament active volume are 1016, 3×1014, and 3×1015 cm−3, and allows efficient oxidative chemistry of nitrogen, resulting in concentrations of HNO3 in the parts per million range. The latter forming binary clusters with water, our results provide a plausible pathway for the efficient nucleation recently observed in laser filaments

Laser-filamentation-induced condensation and snow formation in a cloud chamber

“…Due to the high electron density of ∼10 16 cm −3 in the self-guided ionized filaments [8][9][10][11][12], water condensation around the filaments has been observed in both saturated and subsaturated conditions [1]. It was proposed that the photo-oxidative chemistry of nitrogen induces the binary H 2 O-HNO 3 nucleation, on which water droplets could grow [1][2][3]. However, a significant rainmaking would not take place if the cloud seeding via the laser-induced binary H 2 O-HNO 3 nucleation was only limited in and around the filament's active volume, which has a diameter of ∼100 μm [9].…”

“…© 2012 Optical Society of America OCIS codes: 120.3940, 140.3450, 260.5130. In the past few years, the Teramobile group demonstrated laser-assisted water condensation both in a cloud chamber and the atmosphere [1][2][3]. The ideas are different from classical cloud seeding by firing massive amounts of carbonic ice, silver iodide, etc., into the atmosphere [4][5][6].…”

Influence of pulse duration, energy, and focusing on laser-assisted water condensation

“…Indeed, it was recently discovered that O 3 , NO, and NO 2 are generated in laser filaments in amounts largely sufficient to produce HNO 3 in the multi-ppm range. 8 Besides unveiling the mechanism of the phenomenon, the influence of the laser parameters is a key question for maximizing it and thus for obtaining macroscopic effects in the atmosphere.…”

Multijoule scaling of laser-induced condensation in air

“…10,11 They convey a typical intensity of 5 Â 10 13 W/cm 2 at kilometerrange distances, 12 generating large amounts of oxidized species like O 3 , NO, and NO 2 , which subsequently generate hygroscopic HNO 3 . 13 The latter allows binary HNO 3 -H 2 O condensation well below 100% relative humidity (RH), 14 in a similar manner to the well-known H 2 SO 4 -H 2 O binary condensation. [15][16][17][18] However, work up to now was restricted to moderate laser energies (some hundreds of mJ or less) and powers (a few TW), which are unable to initiate macroscopic effects on large atmospheric volumes.…”