Temperature dependence of optical rotation on parity-violating phase transition of D-, L, and DL alanine crystals 张淼白凡 北京大学物理系九九级 指导老师:杜为民王文清
Temperature dependence of optical rotation on Temperature dependence of optical rotation on parity - violating phase transition of D violating phase transition of D -, L -, and DL , and DL - alanine alanine crystals crystals 张淼 白凡 北京大学物理系九九级 北京大学物理系九九级 指导老师：杜为民 指导老师：杜为民 王文清
Part i abstract Chirality in Biological System Salam Theory: Theory and Supposed Experiment Previous Work Our experiment
Part I Abstract Part I Abstract ¾ Chirality Chirality in Biological System in Biological System ¾ Salam Theory: Theory and Supposed Salam Theory: Theory and Supposed Experiment Experiment ¾ Previous Work Previous Work ¾ Our Experiment Our Experiment
Introduction: Chirality all biomolecules have to be of one hand. so homochirality is a hallmark of life. a Life is based on L-amino acids and D-sugars rather than the enantiomeric d-amino acids and L-sugars. This broken symmetry is now believed to be a feature of fundamental physics a result of symmetry-breaking by the weak force which makes one enantiomer very slightly more stable than the other
Introduction Introduction ：Chirality Chirality All biomolecules biomolecules have to be of one hand, so have to be of one hand, so homochirality homochirality is a hallmark of life. is a hallmark of life. Life is based on L Life is based on L -amino acids and D amino acids and D -sugars rather than the rather than the enantiomeric enantiomeric D -amino acids amino acids and L -sugars. This broken symmetry is now sugars. This broken symmetry is now believed to be a feature of fundamental physics believed to be a feature of fundamental physics ⎯ a result of a result of symmetry symmetry-breaking breaking by the weak force weak force, which makes one , which makes one enantiomer enantiomer very slightly more stable than the other. very slightly more stable than the other
Introduction: Salam Phase Transition Theory a Salam postulated that chirality among the twenty amino acids, which make up the proteins, may be a consequence of a phase transition which is analogous to that due to bCs superconductivity Salam suggested a unique mechanism whereby the parity violating energy difference(PVED between enantiomers might lead directly to a homochiral product. He surmised that there should exist an abrupt phase transition at a critical temperature T, causing a change in the chirality from d-amino acid to that of more stable natural enantiomer. the L-amino acid
Introduction Introduction ：Salam Phase Transition Salam Phase Transition Theory Salam postulated that postulated that chirality chirality among the twenty among the twenty amino acids, which make up the proteins, may be amino acids, which make up the proteins, may be a consequence of a a consequence of a phase transition phase transition which is which is analogous to that due to analogous to that due to BCS superconductivity. superconductivity. Salam suggested a unique mechanism whereby the Salam suggested a unique mechanism whereby the parity violating energy difference ( parity violating energy difference (PVED) between between enantiomers enantiomers might lead directly to a might lead directly to a homochiral homochiral product. He surmised that there should product. He surmised that there should exist an abrupt phase transition at a critical exist an abrupt phase transition at a critical temperature temperature T c, causing a change in the , causing a change in the chirality chirality from D -amino acid to that of more stable amino acid to that of more stable “natural natural ” enantiomer enantiomer, the L , the L -amino acid. amino acid
Introduction: Salam Phase Transition Theory 1=1036o(1-4sinO exp ≈2.5×10K
Introduction Introduction ：Salam Phase Transition Salam Phase Transition Theory K g T eff C 2 3 2 ] 2 . 5 10 ( 1 4sin ) 2 exp[ 10 ≈ × − − = σ θ ϕ