Example: Chiral spectra of S- and R-PBTP thin polymer films of ~10 nm thick.

1. 1 SF signal (arb. units)  2 Sum-Frequency Spectroscopy as a Sensitive Probe for Molecular Chirality Y. Ron Shen, Univ. California, BerkeleyDMR-0341688 A new optical technique, sum-frequency spectroscopy, has been developed to probe molecular chirality. It has significantly higher sensitivity than conventional techniques such as circular dichroism, and allows in situ probing of chirality in electronic and vibrational transitions of thin films and monolayers. It provides opportunities for novel investigation of chiral functions and dynamics of chemical and biological systems. Example: Chiral spectra of S- and R-PBTP thin polymer films of ~10 nm thick. Example: Chiral spectra of S- and R-PBTP thin polymer films of ~10 nm thick.

2. Sum-Frequency Spectroscopy as a Sensitive Probe for Molecular Chirality Y. Ron Shen, Univ. California, BerkeleyDMR-0341688 Molecular chirality is of great importance in chemistry and biology. Conventional techniques, e.g., circular dichroism suffers from low sensitivity. Optical sum-frequency generation has recently been developed into a very sensitive chiral probe. It allows detection of chiral vibrational spectra from monolayers and thin films. Shown above are the first chiral vibrational spectra ever obtained from thin films of chiral polymer. PBTP refers to poly(bithienylene-phenylene). This work suggests that chiral sum-frequency spectroscopy can be generally used to probe in situ molecular chirality and chiral functions of practical chemical and biological systems. (Schematics describing the sum-frequency generation process are included.) (Oh-e et al, PRL 93 (2004))