High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Raman Study of Amino Acids at High Pressures Alanine and its mutimer crystal Korea University Div. of Chemistry & Molecular Engineering Seung-Joon Jeon High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon High Pressure Study Pressure Unit : 1 bar = 10 5 pascal(Pa) = atm 1 GPa = 10Kbar 10 4 atm Pressure Effect in Materials - Isolation of effect on interatomic and/or intermolecular interaction - Phase transtion - Insulator-metal transition Experimental techniques - Dynamic method : shock wave - Static method : pressure cell Diamond Anvil Cell(DAC) High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Diamond Anvil Cell(DAC) Sampling part High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Diamond Anvil Cell High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Pressure calibration with ruby fluorescence Doublet : R nm R nm Red Shift almost linearly with pressure up to 30 GPa P(GPa) = 380.8{(x/ ) 5 - 1} x: R 1 shift with nm Band width is sensitive to hydrostatic condition High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Ruby fluoresence shift with pressure Wavelength (A o ) High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon L-Alanine - Simplest chiral amino acid - Molecular crystal with inter- and/or intra- hydrogen bonding molecule C 1 symmetry crystal orthorombic at 1 atm and room T space group P unit cell dimension : a= 6.032, b= , c=5.784 A Vibrational mode Internal mode: 33 fundamental molecular vibration modes Phonon mode: 6A + 5B(x) + 5B(y) + 5B(z) A sym -6 optical Raman active & IR inactive B sym -15 optical Raman & IR both active L-alanyl-L-alanine Crystal tetragonal space group, I4 unit cell : a=17.985, c= A molecular packing : 4-fold sym High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Tri-L-Alanine -Two different crystal form parallel-chain sheet arrangement(P) platelet form Antiparallel-chain pleated sheet arrangement (AP) needle form -Ala 3 (P) monoclinic, space group P21, unit cell : a=9.862, b=10.004, c= =101.3, Z=4 High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Experimental Sample : Aldrich (99+%), powdered High pressure : DAC Gasket : thickness 250 m steinless steel 300 m diameter hole Pressure calibration : Ruby fluorescence Raman : Jovin-Yvon U m double monochromator PMT + photon counting Back scattering geometry IR : Bomem MB102 FT-IR with Spectra-Bench beam condenser High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Crystal structure L-alanine L-alanyl-L-alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Molecular structure L-alanine L-alanyl-L-alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Ackowlegement Coworker Prof. Hackjin Kim (Chungnam Univ) Prof. Hogyu Han (Korea Univ) Students - Hang Sun Ahn (Ph. D student) - Yong Ho Jung (MS student) Financial support - KOSEF - KOSEF-SRC(CMR-Korea Univ.) High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Conformation Change(or Phase transition) L-Alanine : GPa L-Alanyl-L-alanine : Gpa Tri-L-Alanine : 2.3-3GPa - No evidence of polymerization reaction - dimer : intermolecular H-bonding intramolecular H-bonding with rotation of C-C and C-N maybe ruduce more in c-axis than in a-axis - The conformation changes shows hysteresis High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Raman spectrum of L-Alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon IR spectrum of L-alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon The d /dp of modes of L-alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon IR spectrum of L-Alanyl-L-Alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon IR spectrum of L-Alanyl-L-Alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon The d /dp of modes of L-Alanyl-L-alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Pressure induced frequency change of modes of L-Alanyl-L-Alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon The calculated frequency at different conformations L-Alanyl-L-Alanine : Amide III mode High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Ab initio calculation with conformations Basis set : 6-31G L-Alanyl-L-Alanine High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon The optimized dihedral angle of peptide bond High Pressure Raman Korea Univ. Dept. of Chemistry Seung-Joon Jeon Raman Shift of Ala 3 (P)