Abstract
Dibutyl phthalate vapor nucleation induced by positive polyethylene
glycol (PEG) ions with controlled sizes and charges was experimentally
studied. The ions were produced by electrospray ionization, classified
in a high-resolution differential mobility analyzer, and studied in a
nano condensation nucleus counter of the mixing type. Ionic radii of PEG
varied from 0.52 to 1.56 nm, including from singly to quadruply charged
ions. Some of these ions are fully stretched chains, other are
spherical, and others have intermediate forms, all of them having been
previously characterized by mobility and mass spectrometry studies.
Activation of PEG1080+2 requires a supersaturation almost as high as that required for small singly charged ions and higher than for PEG1080+.
This anomaly is explained by the Coulombic stretching of the ion into a
long chain, where the two charged centers appear to be relatively
decoupled from each other. The critical supersaturation for singly
charged spherical ions falls below Thomson's (capillary) theory and even
below the already low values seen previously for tetraheptyl ammonium
bromide clusters. Spherical PEG4120+2 falls close to the Thomson curve. The trends observed for slightly nonspherical PEG4120+3 and highly nonspherical (but not quite linear) PEG4120+4 are intermediate between those of multiply charged spheres and small singly charged ions.
Original language | English |
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Pages (from-to) | 1133-1138 |
Journal | Journal of Physical Chemistry A |
Volume | 112 |
Issue number | 6 |
DOIs | |
Publication status | Published - 2008 |
MoE publication type | A1 Journal article-refereed |
Keywords
- ion-induced nucleation
- nucleation
- polyethylene glycol
- PEG
- electrospray
- electrospray ionization