XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
209
T1: P–76
Spectroscopic studies of membranes fabricated
of the modified carbon nano-fibers
Aleksandra Wesełucha-Birczyńska
1
, Elżbieta Długoń
2
, Krzysztof Morajka
1
, Marek
Michalec
1
, and Marta Błażewicz
2
1
Faculty of Chemistry, Jagiellonian University, Ingardena 3, Krakow, Poland,
e-mail: birczyns@chemia.uj.edu.pl
2
Faculty of Materials Science and Ceramics, AGH-University of Science and Technology,
Mickiewicza 30, Kraków, Poland
Carbon nanofibres are relatively new multifunctional materials that are extremely promising
for a wide range of applications, medical, industrial and other [1–3]. Despite the literature and
knowledge that has been developed in the field of carbon nanomaterial research, from the point
of view of medical applications, there is still no coherent theory that explains their effects on
living organism.
The micro-Raman spectra of three membrane samples formed of carbon nanofibers, the
reference, oxidized and heated to 2800°C were collected with Renishaw inVia spectrometer with
442 nm, 514.5 nm and 785 nm laser lines as an excitation source. The X-ray diffraction data of
these membranes were collected on the Philips diffractometer type X’Pert Pro in the Bragg-
Brentano geometry, using CuKα radiation (λ = 0.154184 nm).
Both methods show the effect of fabrication and modification techniques on the structure
and ordering of the carbon membranes.
The degree of crystallinity of analyzed membranes was estimated, as the ratio of the
intensity of respective Raman bands. Applying model of two band in the Raman spectra in the
range of 1800–900 cm
–1
, the D1/G intensity ratio is equal to 1.05±0.06, 1.02±0.02, and
0.27±0.02 for reference membrane, oxidized and heated sample, respectively, for excitation line
of 514.5 nm. These differences introduced by treatment of the membrane are also seen in
parameter, which is the size of the ordered area within the material. Determined size of
crystalline domains La is equal to 16.13±0.8 nm, 16.45±0.25 nm, and 60.94±5.15 nm for
reference membrane, oxidized and heated sample, respectively [4]. These data indicate that
oxidation introduces some structural modification, changes fibers alignment but the
graphitization process changes significantly the molecular arrangement in the material [5].
The resulting diffractive images indicate a clear effect of the chemical and thermal treatment
on the studied membranes. Oxidation seems to lead to partial amorphization of material as
indicated by the appearance of characteristic amorphous hump, while heated sample shows the
appearance of different crystalline phase. The emerging new phase reveals a different crystalline
character. The width and shape of new peak indicate changes at the nanostructural level.
Keywords: carbon nano-fibre; Raman microspectroscopy; X-ray diffraction
Acknowledgment
This project was financed from the National Science Centre (NCN, Poland) granted on the decision number
DEC-2013/09/B/ST8/00146 and UMO-2014/13/B/ST8/01195.
References
[1] S. Liao, B. Li, Z. Ma, H. Wei, C. Chan, S. Ramakrishna, Biomed. Mater. 1 (2006) R45.
[2] S. Pramanik, B. Pingguan-Murphy, N.A.A. Osman, Sci. Technol. Adv. Mater. 13 (2012) 043002.
[3] W. Cui, Y. Zhou, J. Chang, Sci. Technol. Adv. Mater. 11 (2010) 014108.
[4] K.P. de Jong, J.W. Geus, Catal. Rev.- Sci. Eng. 42 (2000) 481.
[5] M.A. Pimenta, G. Dresselhaus, M.S. Dresselhaus, L.G. Cancado, A. Jorio, R. Saito, Phys. Chem.
Chem. Phys. 9 (2007) 1276.
[6] I.D. Rosca, F. Watari, M. Uo, T. Akasaka, Carbon 43 (2005) 3124.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
210
T1: P–77
5-Methylhydantoin: structure, spectroscopy, photochemistry and
polymorphism
G. O. Ildiz
1,2
, B. A. Nogueira
1
, J. Canotilho
3
, M. E. S. Eusébio
1
,
M. S. C. Henriques
4
, J. A. Paixão
4
and R. Fausto
1
1
CQC, Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal.
e-mail: g.ogruc@iku.edu.tr
2
Faculty of Sciences and Letters, Department of Physics, Istanbul Kültür University, Ataköy Campus,
Bakirköy 34156, Istanbul, Turkey.
3
Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
4
CFisUC, Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal.
The molecule of 5-methylhydantoin (C4H6N2O2; 5-MH) was studied by matrix isolation
infrared spectroscopy (IR) and density functional theory (DFT) calculations. The electronic
structure of the most stable structure of 5-MH was characterized using the natural bond orbital
(NBO) method. The unimolecular UV-induced photochemistry of the matrix-isolated 5-MH was
followed by IR spectroscopy and led to observation of single photofragmentation pathway,
yielding isocyanic acid, ethanimine and carbon monoxide. This reaction follows the same
pattern as those observed before for both the parent hydantoin and 1-methylhydantoin
molecules.
Figure - The molecule of 5-MH (left) and the PLTM images of the four identified polymorphs
of the compound (top). The crystal structure of polymorph III (bottom) has been determined by
XRD.
The thermal properties of 5-MH were also investigated by differential scanning
calorimetry (DSC), polarized-light thermal microscopy (PLTM) and infrared and Raman
spectroscopies. Four different polymorphs of 5-MH were identified. The crystal structure of one
of this polymorphs (polymorph III) was determined by single crystal X-ray diffraction (XRD),
and two additional polymorphs were characterized by powder XRD.
Keywords: 5-Methylhydantoin, Molecular structure, Polymorphism, IR and Raman spectroscopies, X-ray
analysis, Quantum chemical calculations, Unimolecular photochemical fragmentation, Thermal analysis.
Acknowledgements: Authors thank the Project PTDC/QEQ-QFI/3284/2014 – POCI-01-0145-
FEDER-016617, funded by FCT (Lisbon) and FEDER/COMPETE 2020-EU. The CQC and CFisUC
are supported by FCT (Projects UI0313/QUI/2013 and UID/FIS/04564/2016), also co-funded by
FEDER/COMPETE 2020-EU.
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