Attachment of Water and Alcohol Molecules onto Water and Alcohol Clusters.

Absolute attachment cross sections of single molecules M (M = water, ethanol, or methanol) onto positively charged mass-selected clusters XnH(+) (X = water, ethanol, or methanol) were measured for cluster sizes ranging from tens to hundreds of molecules and center-of-mass collision energies varying from 0.1 to ∼1 eV. The attachment cross sections, which converge as expected toward geometrical cross sections at large cluster sizes, are systematically and noticeably lower than geometrical cross sections at small sizes.

Experimental nanocalorimetry of protonated and deprotonated water clusters.

An experimental nanocalorimetric study of mass selected protonated (H2O)nH(+) and deprotonated (H2O)n-1OH(-) water clusters is reported in the size range n = 20-118. Water cluster's heat capacities exhibit a change of slope at size dependent temperatures varying from 90 to 140 K, which is ascribed to phase or structural transition. For both anionic and cationic species, these transition temperatures strongly vary at small sizes, with higher amplitude for protonated than for deprotonated clusters, and change more smoothly above roughly n ≈ 35.

Observations of nucleation of new particles in a volcanic plume.

Volcanic eruptions caused major weather and climatic changes on timescales ranging from hours to centuries in the past. Volcanic particles are injected in the atmosphere both as primary particles rapidly deposited due to their large sizes on time scales of minutes to a few weeks in the troposphere, and secondary particles mainly derived from the oxidation of sulfur dioxide. These particles are responsible for the atmospheric cooling observed at both regional and global scales following large volcanic eruptions.