Modelling of HNO3-mediated laser-induced condensation: A parametric study

Abstract

Based on both static (extended Köhler) and dynamic modelling, we investigate the influence of temperature, humidity, HNO 3 initial concentration, as well as of the particle concentration, on the efficiency of HNO 3 -mediated laser-induced condensation. This mechanism is most efficient for low temperatures, high HNO 3 concentration, and relative humidities. It is, however, still active up to 30• C, down to 70% relative humidity, and below the ppm level of HNO 3 . Furthermore, lower particle concentration minimizing the depletion of both HNO 3 and water vapor is more favourable to particle growth.

Laser filament-induced aerosol formation

“…Rather, the electron scavenging effect of O 2 , or its capacity to generate ozone, may play an important role. The persistence of new particle formation in argon atmospheres free of elemental nitrogen shows that nitric acid aerosol formation (Henin et al, 2011;Rohwetter et al, 2011) is not the exclusive process that can lead to formation of new particles. As there exist no low vapour pressure species containing just the elements hydrogen, oxygen and argon as present in these experiments, we conclude that the observed particles are related to contaminants in the chamber.…”

“…However, so far only little information on the laser-induced particle formation, potential growth of these particles, and the corresponding uptake of water on these particles is available . It was shown, in particular, that uptake of water on laserinduced particles is assisted by laser-generated hygroscopic HNO 3 Rohwetter et al, 2011), generated in the plasma trail left behind by the laser filaments. Similar results have also been reported for illumination with ultraviolet light (Yoshihara, 2005;Sorokin and Arnold, 2009;Sorokin, 2010).…”

Laser filament-induced aerosol formation

“…Filaments generated by ultrashort laser pulses were recently proposed as candidates to promote condensation of water in the atmosphere (Rohwetter et al, 2010) or generate snow (Ju et al, 2012). However, so far only little information on the laser-induced particle formation, potential growth of these particles, and the corresponding uptake of water on these particles is available (Rohwetter et al, 2011). It was shown, in particular, that uptake of water on laserinduced particles is assisted by laser-generated hygroscopic HNO 3 (Petit et al, 2010;Rohwetter et al, 2011), generated in the plasma trail left behind by the laser filaments.…”

Sub-picosecond chirped laser pulse-induced airflow and water condensation in a cloud chamber

“…It is friendlier to the environment because no extra catalyst is seeded. Nanometer to sub-micrometer-sized aerosols, including hygroscopic nitric acid or ammonium nitrate, along with trace gases, such as SO 2 and oxidized volatile organics, can be produced by femtosecond laser filaments through complex photochemical reactions [9][10][11][12] . These byproducts are shown to be providing major ingredients for the cloud condensation nuclei (CCN) in femtosecond laser-induced condensation.…”

“…When an intense laser beam propagates in air, the formed plasma column can ionize or dissociate air molecules and produce high concentrations of O 3 in the active volume [9,10] , which triggers oxidation reactions of nitrogen and results in the generation of NOx, which finally condenses in the form of HNO 3 or NH 3 NO 3 [12] . These hygroscopic HNO 3 and NH 3 NO 3 provide major condensation nuclei into a cloud.…”