Origin of Clusters. III. On the Possibilities of Production of Mixed Water—Organic Solute Clusters under Fast-Atom Bombardment at Subzero Temperatures

The conditions necessary for formation of mixed water–organic solute clusters under fast-atom bombardment at low temperatures have been investigated by means of mass spectrometry. In the cases of water–ethanol and water–formaldehyde solutions it was concluded that mixed clusters originate from the liquid phase in which the samples exist at certain temperatures as predicted by the phase diagrams of these mixtures. It was found that the observed pattern of mixed clusters was independent of the initial ratio of water to ethanol. An explanation of this finding is suggested. In agreement with previous studies, clusters could not be produced from hydrogen-bonded organic solids. It was, however, found to be possible to sputter hydrate clusters from solid polyoxymethylene derivatives (formed during freezing of formaldehyde–water solutions), due, it is suggested, to a predominance of van-der-Waals type interactions among the oligomers in this solid. Results are discussed in relation to the biophysical and cryobiological problems of stable hydrates, strongly-bound water and mechanisms of action of cryoprotector compounds.