Vibrationally Resolved Sum-Frequency Generation With

l range, 600 cm ) in parallel. The spectral resolution of this approach is determined by the spectrograph and the bandwidth of the nonresonant visible pulse. This BB SFG approach, using a tabletop commercial laser system, rapidly produces excellent spectra and, in principle, permits ultrafast time resolution. Figure 1 details the optical system based on an optical parametric amplifier (OPA) pumped at a 1-kHz repetition rate by a Ti : sapphire regenerative amplifier 3,4 that produces 800-nm pulses with 100-fs FWHM duration, 5 12-nm FWHM bandwidth, and .800-mJ energy. In the OPA a two-pass type II BBO crystal seeded by a white-light continuum produces signal and idler pulses with a combined energy of .220 mJ. The OPA tunes with nearly constant combined power over the range of signal wavelengths from 1200 to 1600 nm. Autocorrelation of the signal at 1311 nm indicates pulses with 100 fs FWHM duration. The signal and the idler bandwidths are 43 nm at 1311 nm and 110 nm at 2091 nm,

HIGH RESOLUTION SPECTROSCOPIC STUDIES OF 1-(1-NAPHTHYL) ETHYLAMINE IN S0S_{0} AND S1S_{1}: EXPLORING THE DEPENDENCE OF CIRCULAR DICHROISM ON CONFORMATIONAL STRUCTURE

Author Institution: Optical Technology Division, National Institute of TechnologyClassical and/or quantum mechanical models developed for isolated molecules are commonly used to extract structural information from optical activity measurements dispite the lack of experimental data for validation of these models. Rotationally-resolved gas phase spectra of the prototypical chiral molecule, 1-(1-Naphthyl) ethylamine (NEA), and its amine deuterated forms have been obtained in the microwave and ultraviolet regions to provide such data. The results of the microwave study indicate that only one conformational form exists under jet-cooled conditions. The substituted atom positions and dipole moment orientation are used to identify the structural configuration of the attached chiral group from amoung nine possible ab initio forms ($B3LYP/6-31G^{\ast}$). The $S_{1}$ inertial parameters and transition moment orientation from the UV data of the band origin at 314 nm have been used to test excited state predictions from ab initio models. CD spectra have also been calculated for the four lowest energy conformations and compared with the observed CD spectrum of (S)-NEA in cyclohexane. These results provide rigorous benchmark data and further elucidate the importance of conformational structure for determinations of absolute stereochemistry from CD spectra. The current progress on gas phase CD measurements will also be discussed

Nonlinear Optics as a Detection Scheme for Biomimetic Sensors:

Vibrational spectra of biomimetic membranes have been obtained using a broad-band approach to sum frequency generation (SFG). A new innovation, broad band SFG (BBSFG) allows for high quality SFG spectra with rapid collection times. With the BBSFG approach, we have followed in situ the formation of a hybrid bilayer membrane (HBM) from the reorganization of phospholipid vesicles at akanethiol monolayers