@article {2479, title = {Narrowband spectroscopy by an all-optical correlation of broadband laser pulses}, journal = {Physical Review A}, volume = {79}, number = {3}, year = {2009}, note = {ISI Document Delivery No.: 427HKTimes Cited: 0Cited Reference Count: 29Konorov, Stanislav O. Xu, Xiaoji G. Hepburn, John W. Milner, Valery}, month = {Mar}, pages = {4}, type = {Article}, abstract = {High-peak-power ultrafast lasers are widely used in nonlinear spectroscopy, but often limit its spectral resolution because of the broad frequency bandwidth of ultrashort laser pulses. Improving the resolution by achieving spectrally narrow excitation of, or emission from, the resonant medium by means of multiphoton interferences has been the focus of many recent developments in ultrafast spectroscopy. We demonstrate an alternative approach in which high resolution is exercised by detecting narrow spectral correlations between broadband excitation and emission optical fields. All-optical correlation analysis, easily incorporated into a traditional spectroscopic setup, enables direct, robust, and simultaneous detection of multiple narrow resonances in a single measurement.}, keywords = {2-PHOTON, 2ND-HARMONIC GENERATION, CARS, COHERENT, DYNAMICS, FEMTOSECOND PULSES, high-speed optical techniques, laser beams, measurement by laser beam, microscopy, MULTIPHOTON INTRAPULSE INTERFERENCE, multiphoton processes, optical correlation, STOKES-RAMAN SCATTERING}, isbn = {1050-2947}, url = {://000264770200011}, author = {Konorov, S. O. and Xu, X. J. G. and Hepburn, J. W. and Milner, V.} } @article {2499, title = {Surface-enhanced IR-visible sum frequency generation vibrational spectroscopy}, journal = {Physical Chemistry Chemical Physics}, volume = {11}, number = {18}, year = {2009}, note = {ISI Document Delivery No.: 436KPTimes Cited: 2Cited Reference Count: 79Li, Qifeng Kuo, Chiung Wen Yang, Zheng Chen, Peilin Chou, Keng C.}, pages = {3436-3442}, type = {Article}, abstract = {Surface-enhanced IR-visible sum frequency generation (SFG) was studied using Ag and Au films over nanospheres (AgFON and AuFON), which provided large area of reproducible nanoscale structures with well-defined morphology. SFG vibrational spectra for a self-assembled monolayer of octadecanethiol were investigated on spheres with diameters ranging from 300 nm to 620 nm. With an input wavelength of 532 nm, a sphere diameter near 360 nm produced the maximum enhancement, which was consistent with the localized surface-plasmon resonant wavelength identified by minimum reflectivity. The measured second-order susceptibility for the asymmetric CH3 stretch mode of octadecanethiol was enhanced by up to 27 times on AgFON, which corresponded to an SFG enhancement factor of similar to 730. The SFG enhancement factor for AuFON was a quarter of that from AgFON. The SFG enhancement factor for the symmetric CH3 mode was about 10 times smaller than that for the asymmetric CH3 mode. This difference can be explained by the highly directional electrical-field parallel to the surface, created at the junction between nanospheres. Polarization-dependent studies also indicated that excitations with the electrical field parallel to the surface was the main contribution to the observed surface enhancements, and the electrical field perpendicular to the surface offered little enhancement.}, keywords = {2ND-HARMONIC GENERATION, METAL NANOPARTICLES, NANOPARTICLES, NANOSPHERE, platinum, RAMAN-SCATTERING SERS, RHODAMINE 6G MOLECULES, SELF-ASSEMBLED MONOLAYERS, SILVER ELECTRODE, SPECTRA, SUPPORTED PD NANOPARTICLES, SURFACES, TOTAL-REFLECTION}, isbn = {1463-9076}, url = {://000265413300011}, author = {Li, Q. F. and Kuo, C. W. and Yang, Z. and Chen, P. L. and Chou, K. C.} }