Photoionization of Sodium Salt Solutions in a Liquid Jet

Abstract

A liquid microjet was employed to examine the gas/liquid interface of aqueous sodium halide (Na + X -, X ) Cl, Br, I) salt solutions. Laser excitation at 193 nm produced and removed cations of the form H + (H 2 O) n and Na + (H 2 O) m from liquid jet surfaces containing either NaCl, NaBr or NaI. The protonated water cluster yield varied inversely with increasing salt concentration, while the solvated sodium ion cluster yield varied by anion type. The distribution of H + (H 2 O) n at low salt concentration is identical to that observed from lowenergy electron irradiated amorphous ice, and the production of these clusters can be accounted for using a localized ionization/Coulomb expulsion model. Production of Na + (H 2 O) m is not quantitatively accounted for by this model but requires ionization of solvation shell waters and a contact ion/Coulomb expulsion mechanism. The reduced yields of Na + (H 2 O) m from high concentration (10 -2 and 10 -1 M) NaBr and NaI solutions indicate a propensity for Brand Iat the solution surfaces and interfaces. This is supported by the observation of multiphoton induced production and desorption of Br + and I + from the 10 -2 and 10 -1 M solution surfaces.

Roles of Water, Acidity, and Surface Morphology in Surface-Assisted Laser Desorption/Ionization of Amino Acids

“…If the holes or protons are localized at a shorter distance than the typical screening length, then Coloumb ejection of cations and protonated species will occur. 36 The efficacy of this Coloumb ejection process can be enhanced by the existence of pre-existing ions at interfaces, 51 and this could be associated with the strong effect observed with increasing acidity.…”

Water Adsorption, Solvation, and Deliquescence of Potassium Bromide Thin Films on SiO2 Studied by Ambient-Pressure X-ray Photoelectron Spectroscopy

“…[3][4][5][6][7] An important factor that amplifies the reaction of Brwith ozone is the increased concentration of Brat the air-saline droplet interface. Various experiments [8][9][10][11][12][13][14] and simulations [15][16][17][18] on alkali halide solutions have demonstrated the propensity of large anions to segregate to the water-air interface. However, a large fraction of aerosols suspended in air are not pure alkali halide crystals but a mixture of dust particles from the deserts with salt crystals deposited on them as they are transported over oceanic regions.…”

“…A considerable number of studies have been published on the mechanisms by which Br − may react with ozone gas in the troposphere, leading to ozone depletion. – An important factor that amplifies the reaction of Br − with ozone is the increased concentration of Br − at the air−saline droplet interface. Various experiments – and simulations – on alkali halide solutions have demonstrated the propensity of large anions to segregate to the water−air interface. However, a large fraction of aerosols suspended in air are not pure alkali halide crystals but a mixture of dust particles from the deserts with salt crystals deposited on them as they are transported over oceanic regions. – Although anion segregation at the air−liquid interface of pure saline solution is now well-established, the same phenomenon has not yet demonstrated for the case of nanometer-scale-thick films of saline solution on solid surfaces.…”

Inert Gas Scattering from Liquid Hydrocarbon Microjets

“…The liquid microjet increases the accessible vapor pressure range to several Torr, and has become a technique widely used for spectroscopic studies of aqueous solutions. ,− This method, shown in Figure b, relies on the use of a cylindrical liquid jet whose 5–50 μm radius generates a sparse vapor blanket around the liquid stream. The number of collisions N coll between a trace gas molecule and evaporating solvent molecules can be estimated from, N coll = ∫ d r /λ( r ), where λ( r ) ≈ (√2 σn ( r )) −1 is the mean free path at a distance r from the center of the jet, calculated from the collision cross section σ and vapor density n ( r ).…”