超快光学-第14章-超快光谱.pptVIP

Heterodyned ultrafast polarization spectroscopy of CS2 Loughnane, et al., Ultrafast Phenomena X, p. 304 (1996). OHD-RIKES study of CS2 at different temperatures. Temporally and spectrally resolving the fluorescence of an excited molecule Exciting a molecule and watching its fluorescence reveals much about its potential surfaces. Ideally, one would measure the time-resolved spectrum, equivalent to its intensity and phase vs. time (or frequency). Here, excitation occurs to a predissociative state, but other situations are just as interesting. Analogous studies can be performed in absorption. Time-frequency-domain absorption spectroscopy of Buckminster-fullerene Brabec, et al., Ultrafast Phenomena XII, p. 589 (2000). Electron transfer from a polymer to a buckyball is very fast. It has applications to photo-voltaics, nonlinear optics, and artificial photosynthesis. Ultrafast Spectroscopy of Photosynthesis Arizona State University The initial events in photosynthesis occur on a ps time scale. Multi-dimensional nonlinear spectroscopy Cresyl violet Measure signal out vs. various input delays and wavelengths Hannaford and coworkers, UP 2004 Higher-order processes can be useful. Here, six-wave mixing helps to delineate vibrational motion in liquids. Steffen and Duppen, Ultrafast Phenomena X, p. 213 (1996). Other ultrafast spectroscopic techniques Photon Echo Transient Coherent Raman Spectroscopy Transient Coherent Anti-Stokes Raman Spectroscopy Transient Surface SHG Spectroscopy Transient Photo-electron Spectroscopy Almost any physical effect that can be induced by ultrashort light pulses! More sophisticated pulse measurement in ultrafast spectroscopy This yields more information in all measurements. Indeed, use of spectral interferometry heterodynes the signal pulse measurement and so improves sensitivity, too. More recently ultrafast spectroscopists have begun taking advantage of more sophisticated pulse-measurement techniques, making a FROG measurement of the