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  • 08월 28일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

Femtosecond phase-and-amplitude detection of optical activity free-induction-decay: Alternative approach for ultrafast time-resolved circular dichroism spectroscopy

2008년 8월 11일 17시 26분 51초
31P157포 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
목 <발표Ⅰ>
저자 및
이한주, 전영건, 김지환, 조민행
고려대학교 화학과, Korea
A better understanding of chiro-optical properties manifested by all living organisms is critical for studies of the molecular basis of biological activity. Particularly, the time-resolved circular dichroism (CD) spectroscopy can provide crucial information on the structural changes undergone in biomolecules in the process of their function. However, the CD is a notoriously weak effect, which renders the time-resolved CD spectroscopy experimentally difficult. Moreover, time-resolved vibrational CD (VCD) experiment has never been carried out before. Recently, we have developed a femtosecond optical activity free-induction-decay (OA FID) measurement technique utilizing a combination of cross-polarization geometry and heterodyned spectral interferometric detection. Direct heterodyne-detection of the phase and amplitude of OA FID field enabled us to overcome the weak-signal and nonzero achiral background problems of the conventional differential CD measurement method. Consequently, we could detect much weaker vibrational OA (VOA) FID fields of small chiral organic molecules in comparison with the electronic one and retrieve their individual VCD and VORD spectra simultaneously via the Fourier transform spectral interferometry (FTSI). In addition, we found that the present method has a highly phase-sensitive detection capability of separating the chiral and achiral FID signals. Combined with pump-probe experiment, our method, which is a CD analog of pulsed NMR, will be a valuable tool for observing the ultrafast chirality changes of biomolecules and therefore allow us to study their dynamics in aqueous solution at physiological conditions.