scholarly journals High Pressure Raman Spectra of Amino Acid Crystals

10.5772/32533 ◽  
2012 ◽  
Author(s):  
Paulo de Tarso Cavalcante Freire ◽  
Jos Alves Lima Jnior ◽  
Bruno Tavares de Oliveira Abagaro ◽  
Gardnia de Sousa Pinheiro ◽  
Jos de Arimata Freitas e Silva ◽  
...  
Keyword(s):  
High Pressure ◽  
Amino Acid ◽  
Raman Spectra

Nitroethane at high density: an experimental and computational vibrational study

2021 ◽  
Vol 23 (15) ◽  
pp. 9325-9336
Author(s):  
Akio Yoshinaka ◽  
Serge Desgreniers ◽  
Anguang Hu
Keyword(s):  
High Pressure ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Unit Cell ◽  
High Density ◽  
Monoclinic Unit Cell ◽  
Vibrational Study

Raman and IR vibrational spectra confirm two molecular units associated with the monoclinic unit cell of nitroethane under high pressure. Raman spectra are extremely sensitive to predicted effects of unit cell distortion due to changes in H-bonding.

scholarly journals Комбинационное рассеяние света в хирально чистых и рацемической фазах поликристаллов триптофана и тирозина

2019 ◽  
Vol 127 (10) ◽  
pp. 541
Author(s):  
В.С. Горелик ◽  
М.Ф. Умаров ◽  
Ю.П. Войнов
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Raman Spectra ◽  
Spectral Range ◽  
Phase State ◽  
Source Parameters ◽  
Low Frequency ◽  
Aromatic Amino Acids ◽  
Chiral Phase ◽  
Left Handed

AbstractRaman spectra of tryptophan and tyrosine polycrystals have been analyzed in a wide spectral range by fiber-optic spectroscopy. The Raman spectra have been recorded with a BWS465-785H spectrometer in the spectral range of 0–2700 cm^–1 using a 785-nm cw laser as an excitation source. Parameters of the Raman spectra are compared for three crystalline phase modifications of aromatic amino acids: left-handed, right-handed, and racemic phase. The presence of strong Raman satellites, the characteristics of which change depending on the type of the chiral phase state of amino acid, is found in the low-frequency Raman spectra of tryptophan and tyrosine amino acid lattices. The results obtained can be used for monitoring the chiral purity of bioactive preparations containing amino acids.

scholarly journals Phase Transition and Polymerization of Acetonitrile under High Pressure

2014 ◽  
Vol 70 (a1) ◽  
pp. C763-C763
Author(s):  
Haiyan Zheng ◽  
Kuo Li ◽  
George Cody ◽  
Chris Tulk ◽  
Jamie Molaison ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Reaction Mechanism ◽  
Neutron Diffraction ◽  
Raman Spectra ◽  
Hydrogen Transfer ◽  
Layer Structure ◽  
Van Der Waals ◽  
Orthorhombic Phase ◽  
Organic Polymer

Successful application of high pressure on synthesis of organic polymer, including the conducting polymer and super hard materials depends on the knowledge of reaction mechanism. The evolution of crystal structure under high pressure especially the structure close to transition pressure is crucial to conclude the reaction mechanism. Nitriles represent a large class of interstellar molecules and are the potential source of amino acids. Understanding its behavior at extreme conditions has gained increasing attention recently. Acetonitrile (CH3CN), the simplest organic compound with C≡N triple bond, can act as a model system for studying the pressure induced polymerization. The phase transition of acetonitrile under high pressure has been studied extensively.[1-3] However, it is still controversial and there is no any detailed discussion about its polymerization mechanism under high pressure. Here, we report the in-situ high pressure Raman spectra and powder neutron diffraction results on CD3CN, which indicates a minor phase transition at 5 GPa. The neutron diffraction shows that CD3CN keeps the orthorhombic phase from 1.66 GPa to 20.58 GPa which is very close to the reaction pressure. The week hydrogen bonding CD...N arranges the molecule into 3-dimensional framework which can be treated as two sets of diamond like structures interpenetrating with each other. Interestingly, the observed N...D distance is 1.984 Å at 20.58 GPa, shorter than the van der Waals distance of N...H (2.75 Å) by 28%. The van der Waals separation is often taken as a reference distance for the molecular instability. Thus, a hydrogen transfer process during the polymerization can be concluded. This deduction is also supported by the solid state NMR and FTIR results of the recovered polymerized CH3CN (p-CH3CN) from high pressure. In addition, the atomic pair distribution function and Raman spectra indicate the p-CD3CN or p-CH3CN has a random packed layer structure with nano-graphene lattice.

Vibrational properties of Cs4 W11 O35 and Rb4 W11 O35 systems: high pressure and polarized Raman spectra

2011 ◽  
Vol 42 (3) ◽  
pp. 474-481 ◽  
Author(s):  
K. Pereira da Silva ◽  
W. Paraguassu ◽  
M. Maczka ◽  
A. G. Souza Filho ◽  
P. T. C. Freire ◽  
...  
Keyword(s):  
High Pressure ◽  
Raman Spectra ◽  
Vibrational Properties ◽  
Polarized Raman
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