Adsorption of Hydroxyacetone on Pure Ice Surfaces

Abstract

The adsorption of hydroxyacetone molecules at the surface of ice is investigated by means of flow-tube reactor measurements in the temperature range: 213-253 K. The number of molecules adsorbed per surface unit is conventionally plotted as a function of the absolute gas concentration of hydroxyacetone and is compared to that previously obtained for acetone and ethanol. The enthalpy of adsorption and the monolayer capacity at the ice surface are determined. In addition, molecular dynamics simulations are performed to support the experimental results. However, it is shown that the available interaction potential between hydroxyacetone and ice is not accurate enough to allow a robust detailed analysis of the adsorption process. Finally, a rapid estimation of the hydroxyacetone partitioning between the gas phase and ice shows that in the densest ice clouds, up to 29% of hydroxyacetone could be adsorbed on pure ice surfaces at 203 K.

Water and formic acid aggregates: A molecular dynamics study

“…This is indeed the case for a wide variety of atmospherically relevant organic compounds for which the accuracy of the interaction models with water has been tested in recent years, on the basis of classical molecular dynamics and Monte Carlo simulations aiming at investigating VOC adsorption on, i.e., ice surfaces. [8][9][10][11][12][13][14][15][16][17][18] A few molecular dynamics simulation studies have thus been recently devoted to a detailed investigation of the behavior of large droplets made of water and organic molecules used as surrogates for organic aerosols. Either big water droplets coated by various organic molecules [19][20][21][22][23][24] or the reverse situation, i.e., large organic aggregates interacting with surrounding water molecules 25,26 have been considered in the corresponding theoretical works, as a function of temperature.…”

Adsorption of Methylamine at the Surface of Ice. A Grand Canonical Monte Carlo Simulation Study

“…[23][24][25][26][27][28][29][30][31][32] In addition, Grand Canonical Monte Carlo (GCMC) simulations 17,33 have also been performed to simulate the adsorption isotherms of various classes of volatile organic compounds and atmospheric pollutants on ice at low temperatures. [34][35][36][37][38][39][40][41][42][43][44] Indeed, the GCMC method is particularly suitable for studying adsorption, because in this method the chemical potential rather than the number of the adsorbate molecules is fixed in the simulation.…”

Comparative Adsorption of Acetone on Water and Ice Surfaces

“…Acetone is a typical small oxygenated organic molecule found in the troposphere, and a critical contributor to the formation of HO x radicals . Owing to its atmospheric relevance, acetone interacting with ice has been studied for decades, for instance by mass spectrometry and X‐ray absorption spectroscopy . Mass spectrometry has been used to quantify the kinetics of acetone adsorption on ice and has provided evidence that adsorption is reversible.…”

“…[1] Acetone is at ypical small oxygenated organic molecule found in the troposphere,a nd ac ritical contributor to the formation of HO x radicals. [2] Owing to its atmospheric relevance,a cetone interacting with ice has been studied for decades,f or instance by mass spectrometry [3][4][5][6] and X-ray absorption spectroscopy. [7] Mass spectrometry has been used to quantify the kinetics of acetone adsorption on ice and has provided evidence that adsorption is reversible.H owever, these gas-phase studies do not provide molecular-level details on the adsorption of acetone,oronhow its adsorption affects the ice and water surfaces.W ater is present in both forms in the troposphere,and the reactions of small organic molecules on water and ice can be very different.…”