Hydrogen bond rearrangements and the motion of charge defects in water viewed using multidimensional ultrafast infrared spectroscopy

Compared with other molecular liquids, water is highly structured due to its ability to form up to four hydrogen bonds to its nearest neighbors, resulting in a tetrahedral network of molecules. However, this network is highly dynamic, exhibiting fluctuations and rearrangements that take place on femtosecond to picosecond time scales. The transport of excess protons and proton holes in water makes exclusive use of water's hydrogen bonding network. Compared to ions of similar size and charge density, both hydronium and hydroxide ions exhibit anomalously high diffusion rates due to the fact that water molecules that neighbor these ions can undergo a proton transfer reaction with the ion. This allows the structural diffusion of the ion to occur apart from the displacement of individual water molecules. In this thesis we adopt a joint experimental and theoretical approach to characterize the fluctuations of water's hydrogen bonding network and how these fluctuations act to drive the structural diffusion of the aqueous hydroxide ion. The experimental data that we present consists of a series of ultrafast nonlinear infrared spectroscopies, in particular two-dimensional infrared spectroscopy (2D IR), applied to the O-H stretching transition of a dilute solution of HOD in NaOD/D20. The frequency of the O-H stretch, (OH, is highly sensitive to the configuration of its hydrogen bonding partner. 2D IR spectroscopy allows us to measure rapid shifts in OH that reveal time scales for changes in the local environment of the HOD molecule.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemistry.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2010

Author dc:creator

• Roberts, Sean T. (Sean Thomas)

Advisor dc:contributor.advisor

• Andrei Tokmakoff.

• Chemistry.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/57678

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/57678