date: 2010 August 11 (Wed) 15:00-16:00
room: Kobe University, Science and Technology Research Building #4-809
speaker: Jun-ichi Takahashi (NTT Microsystem Integration Laboratories)
title: Circularly polarized light in space and its relationship to the origin of terrestrial homochirality
abstract: One of the most attractive hypothesis for the origin of homochirality in terrestrial bio-organic compounds (L-amino acid and D-sugar dominant) is nominated as “Cosmic Scenario”; a chiral impulse from asymmetric excitation sources in space triggered asymmetric reactions on the surfaces of such space materials as meteorites or interstellar dusts prior to the existence of terrestrial life. Effective asymmetric excitation sources in space are proposed as polarized quantum beams, such as circularly polarized photons and spin polarized electrons. It has been advocated that circularly polarized photons can be emitted as synchrotron radiation from tightly captured electrons by intense magnetic fields around neutron stars and that spin polarized electrons can be emitted as beta-ray in beta decay from radioactive nuclei or neutron fireballs in supernova explosion. Actual observations of these kinds of radiation, however, have not been reported yet. Recently, widely-spreading circularly polarized components in infrared light from a massive star formation region has been actually observed and, in consequence, the “Cosmic Scenario” has attracted increasing attention anew.
For the purpose of verifying the optical activity emergence in bioorganic compounds by polarized quantum beams, we are carrying out laboratory simulations using circularly polarized light from free electron laser or spin polarized electron beam from beta-ray radiation source, which simulate asymmetric energy sources in space. The target samples are aqueous solutions or solid films of racemic amino acids and complex organic compounds including amino acid precursors, which simulate organic compounds abiologically formed on the surface of interstellar dusts. In my lecture, possible asymmetric reactions induced by these kinds of asymmetric energy sources will be discussed and our recent progress on the simulating experiments will be reported.