scholarly journals Investigation of the β–γ phase transition in single crystal malononitrile by polarized Raman spectroscopy

1993 ◽  
Vol 99 (8) ◽  
pp. 5637-5645 ◽  
Author(s):  
S. J. Bonafede ◽  
C. J. Eckhardt
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
Single Crystal ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman

Optical phonons in millerite (NiS) from single-crystal polarized Raman spectroscopy

2008 ◽  
Vol 39 (10) ◽  
pp. 1419-1422 ◽  
Author(s):  
François Guillaume ◽  
Shanshan Huang ◽  
Kenneth D. M. Harris ◽  
Michel Couzi ◽  
David Talaga
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystal ◽  
Optical Phonons ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman

scholarly journals The Only N-H...O Hydrogen Bond - Two Ways to Build a Structure of Dimethylglycine

2014 ◽  
Vol 70 (a1) ◽  
pp. C550-C550
Author(s):  
Eugene Kapustin ◽  
Vasily Minkov ◽  
Elena Boldyreva
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Amino Acids ◽  
Raman Spectroscopy ◽  
Single Crystal ◽  
Van Der Waals Interactions ◽  
X Ray Diffraction ◽  
Space Symmetry ◽  
Polarized Raman ◽  
Crystalline Amino Acids

Crystalline amino acids are considered to mimic important interactions in peptides, therefore the studies of the structure-forming factors in these systems attract much attention. N,N-dimethylglycine is an interesting model compound that was used to test the role of the N-H...O H-bonds in forming the head-to-tail chains – the main structural unit in the crystals of amino acids. It was hypothesized previously that additional side N-H...O H-bonds play an important role in forming the head-to-tail chains of amino acid zwitterions linked via N-H...O H-bonds between the charged -NH3 and -COO terminal groups. Twice methylated amino group of N,N-dimethylglycine is able to form only one N-H...O H-bond in the crystal structure, so that this hypothesis could be tested. There are two polymorphs of N,N-dimethylglycine, in which the zwitterions are packed in two different ways. In one polymorph (orthorhombic, Pbca) they form finite four member ring motifs not linked to each other via any H-bonds, but only by weak van der Waals interactions. However, in the second polymorph (monoclinic, P21/n) the zwitterions do form infinite head-to-tail chains though the N-H...O H-bond is the only one and is not assisted via any additional H-bonds. The effect of cooling on the two crystal structures was followed by single-crystal X-ray diffraction combined with polarized Raman spectroscopy of oriented single crystals, in order to compare the response of the N-H...O H-bonds to temperature variations. The crystal structure of the monoclinic polymorph compresses anisotropically on cooling, whereas that of the orthorhombic polymorph undergoes a reversible single-crystal to single-crystal phase transition at ~200 K accompanied by non-merohedral twinning, reducing the space symmetry to monoclinic (P21/b), and doubling the asymmetric unit from 2 to 4 molecules. This phase transition could not be detected by Raman spectroscopy and DSC because of the subtle related changes in intermolecular energies.

Effect of pressure on crystalline L- and DL-serine: revisited by a combined single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy study

2012 ◽  
Vol 68 (3) ◽  
pp. 275-286 ◽  
Author(s):  
Boris A. Zakharov ◽  
Boris A. Kolesov ◽  
Elena V. Boldyreva
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effect Of Pressure ◽  
Laboratory Source ◽  
Compression Mechanism ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman

Information on the effect of pressure on hydrogen bonds, which could be derived from single-crystal X-ray diffraction at a laboratory source and polarized Raman spectroscopy, has been compared. L-Serine and DL-serine were selected for this case study. The role of hydrogen bonds in pressure-induced phase transitions in the first system and in the structural stability of the second one are discussed. Non-monotonic distortion of selected hydrogen bonds in the pressure range below ∼ 1–2 GPa, a change in the compression mechanism at ∼ 2–3 GPa, and the evidence of formation of bifurcated N—H...O hydrogen bonds in DL-serine at ∼ 3–4 GPa are considered.

Manifestation of strong magnetic and giant Raman anisotropy in single crystals of Cu for H substituted strontium hydroxyapatite

CrystEngComm ◽  
2019 ◽  
Vol 21 (33) ◽  
pp. 4976-4980
Author(s):  
Pavel E. Kazin ◽  
Mikhail A. Zykin ◽  
Anton Jesche ◽  
Maximilian L. Seidler ◽  
Victor A. Tafeenko ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Magnetic Anisotropy ◽  
Single Crystal ◽  
Single Crystals ◽  
Easy Axis ◽  
High Energy ◽  
Magnetization Measurements ◽  
Strontium Hydroxyapatite ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman

The linear [O–Cu–O]− reveals a strong easy axis magnetic anisotropy with a high energy of 4 × 102 cm−1 probed by magnetization measurements and polarized Raman spectroscopy of a single crystal.

Polarized Raman spectroscopy of Cu-poor and Zn-rich single-crystal Cu2ZnSnSe4

2014 ◽  
Vol 105 (17) ◽  
pp. 173903 ◽  
Author(s):  
Dahyun Nam ◽  
Jungcheol Kim ◽  
Jae-Ung Lee ◽  
Akira Nagaoka ◽  
Kenji Yoshino ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystal ◽  
Polarized Raman Spectroscopy ◽  
Polarized Raman
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