| Advances in surface broad bandwidth sum frequency generation (BBSFG) spectroscopy and investigations of liquid surfaces are discussed in this dissertation. The technique implemented uses a double amplifier ultrafast laser system to produce a narrow bandwidth visible beam and a broad bandwidth infrared beam. The two beams are overlapped in time and space on a liquid surface to produce a broad bandwidth sum frequency signal. The double amplifier system allows for higher peak powers resulting in a stronger sum frequency generation response from characteristically low signal liquid surfaces. Several organic liquids are investigated using BBSFG spectroscopy and Raman spectroscopy to investigate the surface structure and the bulk liquids, respectively. The series of liquids selected are applicable to atmospheric aerosol processing. Initially, a surrogate hydrophilic compound ethylene glycol was investigated. In addition to ethylene glycol, several aromatic compounds were probed at their air-liquid interfaces. The aromatic compounds studied were benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, and mesitylene. The final aromatic compound to be studied was 1-methyl naphthalene. The surface of the neat 1-methyl naphthalene liquid is dramatically altered upon the addition of small amounts of water into the bulk liquid. |
