Infrared spectroscopy of ion-hydrocarbon clusters

Many biological and environmental systems contain ion, water, and hydrophobic components; and it is the balance between these competing interactions which governs their chemistry. This Thesis aims at exploring ion•••hydrocarbon interactions, then ion•••water•••alkane interactions. To accomplish this, a combination of gas phase infrared predissociation spectroscopy (IRPD) and tandem mass spectrometry is utilized. The solvation of alkali metal ions by methane is discussed first, beginning with the effects of multiple argon atoms on Li+•••CH4 dimer clusters followed by a study of M+(CH4)n clusters where it is revealed that ions have a weak electrostatic effect beyond the first solvent shell. Next, the argon tagging and monitoring unique fragmentation channels are used to selectively probe for high energy Li+(H2O)3-4Ar1 conformers which contain extensive water hydrogen bonding. Finally, ion•••water•••alkane interactions are probed in Li+(H2O)n clusters containing CH4 or C6H12 molecules. Some spectra contain hydrogen bonded peaks correlating to weak water•••alkane interactions. Furthermore, there is strong evidence that high energy conformers containing water hydrogen bonding are present in the cluster ion beam. This analysis is expanded to anionic Cl-(Water)m(CH4)n clusters to compare with cations. Density functional theory or MP2 level calculations were used to support and help characterize experimental data.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Rodriguez, Oscar, Jr.

Contributors dc:contributor

• Lisy, James M.
• Luthey-Schulten, Zaida A.
• Gewirth, Andrew A.
• McCall, Benjamin J.

• ion solvation
• fragmentation channels
• infrared spectroscopy
• lithium ion
• water clusters
• methane
• argon tagging
• cyclohexane
• high energy conformer trapping

Statement dc:rights

• Copyright 2011 Oscar Rodriguez Jr.

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/24495

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/24495