Water molecule elimination from the protonated methanol dimer ion-An example of a size-selective intracluster reaction.

The abundance of extraterrestrial methanol makes the reaction between methanol molecules in a molecular cluster a possible key step in the search for mechanisms for the formation of more complex molecules under the conditions of the interstellar medium as well as circumstellar and planetary atmospheres. The reaction leading to the formation of the dimethyl ether ion from a methanol molecule interacting with a protonated methanol ion via the elimination of a water molecule is a basic mechanism for the formation of complex organic molecules. Here, we experimentally examine such reactions in the gas phase, analyzing the production and reactivity of protonated cluster ions formed by the ionization of a supersonic jet of methanol.

Electron-induced ionization and cationic fragmentations of the isolated molecule of 2,4-imidazolidinedione (hydantoin): a study of the relaxing path thresholds.

In this work, our new experimental setup has been used to study the ionization and fragmentation of a prebiotic molecule, hydantoin, by electron impact. Scanning of the incident electron energy allows the determination of the appearance thresholds of the cations. The vertical ionization potential was found to be in good agreement with previous data.

Energy Dispersion in Pyridinium-Water Nanodroplets upon Irradiation.

Postirradiation dissociation of molecular clusters has been mainly studied assuming energy redistribution in the entire cluster prior to the dissociation. Here, the evaporation of water molecules from out-of-equilibrium pyridinium-water cluster ions was investigated using the recently developed correlated ion and neutral time-of-flight (COINTOF) mass spectrometry technique in combination with a velocity-map imaging (VMI) device. This special setup enables the measurement of velocity distributions of the evaporated molecules upon high-velocity collisions with an argon atom.

Impact of a hydrophobic ion on the early stage of atmospheric aerosol formation.

Atmospheric aerosols are one of the major factors affecting planetary climate, and the addition of anthropogenic molecules into the atmosphere is known to strongly affect cloud formation. The broad variety of compounds present in such dilute media and their specific underlying thermalization processes at the nanoscale make a complete quantitative description of atmospheric aerosol formation certainly challenging. In particular, it requires fundamental knowledge about the role of impurities in water cluster growth, a crucial step in the early stage of aerosol and cloud formation.