PHYS 351 |
| We developed a new surface-selective time-resolved nonlinear spectroscopy, femtosecond time-resolved electronic sum-frequency generation (TR-ESFG) spectroscopy, to investigate ultrafast dynamics at liquid interfaces. Its advantage over conventional time-resolved second harmonic generation spectroscopy is that it provides spectral information, which is realized by the multiplex detection of the sum frequency signal using a broadband white light continuum and a multichannel detector. With this new method, we examined the photo-induced dynamics of a surface active dye (rhodamine 800) at the air/water interface and successfully observed transient electronic spectra of interfacial molecules for the first time. We found that the relaxation dynamics exhibited three time constants of 0.32 ps, 6.4 ps, and 0.85 ns, and the 6.4-ps component corresponds to an interface-specific deactivation process. With the TR-ESFG spectroscopy, we can now investigate dynamics at liquid interface as thoroughly as we do for the dynamics in bulk solutions with the conventional femtosecond time-resolved absorption spectroscopy. |
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PHYS Poster Session - Optical Probes of Dynamics in Complex Environments
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Division of Physical Chemistry |