Article

1998 ◽  
Vol 76 (11) ◽  
pp. 1730-1736
Author(s):  
Mathew D Halls ◽  
Ricardo Aroca
Keyword(s):  
Ab Initio ◽  
Normal Modes ◽  
Light Emitting ◽  
Solid Films ◽  
Ft Ir ◽  
First Time ◽  
Mode Assignment ◽  
Transmission And Reflection ◽  
Ft Ir Spectroscopy

The vibrational spectra of one of the most commonly used light-emitting materials for organic electroluminescence (EL) devices, tris(8-hydroxyquinoline)aluminum (Alq3), is presented. The geometry and normal modes of fac-Alq3 isomer in the ground state have been computed for the first time using ab initio methods (HF/6-31G*) to aid in discussion of normal-mode assignment. Normal inelastic scattering excited at 633 nm and low-temperature FT-Raman in addition to the infrared spectra of this material are reported. The vibrational characterization of thin solid films of the material was attempted using transmission and reflection-absorption FT-IR spectroscopy (RAIRS) on smooth silver films.Key words: tris(8-hydroxyquinoline)aluminum, Alq3, ab initio, assignments, infrared, Raman, thin films.

scholarly journals Raman Spectroscopy as a Novel Method for the Characterization of Polydioxanone Medical Stents Biodegradation

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5462
Author(s):  
Jan Loskot ◽  
Daniel Jezbera ◽  
Aleš Bezrouk ◽  
Rafael Doležal ◽  
Rudolf Andrýs ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Hydrolytic Degradation ◽  
Biodegradable Stents ◽  
Ft Ir ◽  
Novel Method ◽  
First Time ◽  
Phosphate Buffered Saline ◽  
Ft Ir Spectroscopy

Polydioxanone (PPDX), as an FDA approved polymer in tissue engineering, is an important component of some promising medical devices, e.g., biodegradable stents. The hydrolytic degradation of polydioxanone stents plays a key role in the safety and efficacy of treatment. A new fast and convenient method to quantitatively evaluate the hydrolytic degradation of PPDX stent material was developed. PPDX esophageal stents were degraded in phosphate-buffered saline for 24 weeks. For the first time, the changes in Raman spectra during PPDX biodegradation have been investigated here. The level of PPDX hydrolytic degradation was determined from the Raman spectra by calculating the area under the 1732 cm−1 peak shoulder. Raman spectroscopy, unlike Fourier transform infrared (FT-IR) spectroscopy, is also sensitive enough to monitor the decrease in the dye content in the stents during the degradation. Observation by a scanning electron microscope showed gradually growing cracks, eventually leading to the stent disintegration. The material crystallinity was increasing during the first 16 weeks, suggesting preferential degradation of the amorphous phase. Our results show a new easy and reliable way to evaluate the progression of PPDX hydrolytic degradation. The proposed approach can be useful for further studies on the behavior of PPDX materials, and for clinical practice.

Photoacoustic FT-IR Spectroscopy of Natural Copper Patina

1995 ◽  
Vol 49 (10) ◽  
pp. 1516-1524 ◽  
Author(s):  
Alex O. Salnick ◽  
Werner Faubel
Keyword(s):  
Depth Distribution ◽  
Depth Profiling ◽  
Beam Deflection ◽  
City Hall ◽  
Spectral Bands ◽  
Special Sample Preparation ◽  
Ft Ir ◽  
Infrared Photoacoustic Spectroscopy ◽  
Ft Ir Spectroscopy

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has proved to be a useful tool for nondestructive testing of copper corrosion layer (patina) formed in the atmosphere. The samples cut from a piece of the roof of the Stockholm City Hall were examined without any additional pretreatment. The components of the patina—brochantite Cu4(OH)6SO4, antlerite Cu3(OH)4SO4, and basic cupric carbonate Cu2CO3(OH)6 · H2O—as well as some other minerals were identified. The photothermal beam deflection (PBD) method was used for independent photoacoustic characterization of the samples. The depth profiling capability of FT-IR/PAS was used to determine the degree of photoacoustic saturation of the spectral bands and to evaluate the depth distribution of the main patina components. The technique thus compares favorably with more common approaches of patina examination which are more expensive and require special sample preparation.

Characterization of SrBi2Nb2O9 Thin Films Prepared by Sol Gel Technique

1996 ◽  
Vol 459 ◽  
Author(s):  
E. Ching-Prado ◽  
W. Pérez ◽  
A. Reynés-Figueroa ◽  
R. S. Katiyar ◽  
D. Ravichandran ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Band ◽  
Sol Gel ◽  
Orthorhombic Symmetry ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Gel Technique ◽  
High Degree ◽  
First Time

ABSTRACTThin films of SrBi2Nb2O9 (SBN) with thicknesses of 0.1, 0.2, and 0.4 μ were grown by Sol-gel technique on silicon, and annealed at 650°C. The SBN films were investigated by Raman scatering for the first time. Raman spectra in some of the samples present bands around 60, 167, 196, 222, 302, 451, 560, 771, 837, and 863 cm−1, which correspond to the SBN formation. The study indicates that the films are inhomogeneous, and only in samples with thicknesses 0.4 μ the SBN material was found in some places. The prominent Raman band around 870 cm−1, which is the A1g mode of the orthorhombic symmetry, is assigned to the symmetric stretching of the NbO6 octahedrals. The frequency of this band is found to shift in different places in the same sample, as well as from sample to sample. The frequency shifts and the width of the Raman bands are discussed in term of ions in non-equilibrium positions. FT-IR spectra reveal a sharp peak at 1260 cm−1, and two broad bands around 995 and 772 cm−1. The bandwidths of the latter two bands are believed to be associated with the presence of a high degree of defects in the films. The experimental results of the SBN films are compared with those obtained in SBT (T=Ta) films. X-ray diffraction and SEM techniques are also used for the structural characterization.

FT-IR spectroscopy characterization of schwannoma: a case study

2016 ◽  
Author(s):  
Isabelle Ferreira ◽  
Lazaro P. M. Neto ◽  
Maurilio José das Chagas ◽  
Luís Felipe C. S. Carvalho ◽  
Laurita dos Santos ◽  
...  
Keyword(s):  
Ir Spectroscopy ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Electrochemically Synthesis and Characterization of Copolymers Based on 1, 4-Diethoxybenzene and 3, 4-Ethylenedioxythiophene

2011 ◽  
Vol 335-336 ◽  
pp. 989-993
Author(s):  
Mi Ouyang ◽  
Zhen Wei Yu ◽  
Yi Xu ◽  
Yu Jian Zhang ◽  
Cheng Zhang
Keyword(s):  
Cyclic Voltammetry ◽  
Ir Spectroscopy ◽  
Feed Ratio ◽  
Synthesis And Characterization ◽  
Monomer Mixture ◽  
Long Wavelength ◽  
H Nmr ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Copolymers based on 1, 4-diethoxybenzene (DEB) and 3, 4-ethylenedioxythiophene (EDOT) were electrochemically synthesized and characterized. The structures of the copolymers were established by 1H NMR and FT-IR spectroscopy. The results indicated the final product was a copolymer instead of a blend or a composite. The physical properties were systematically investigated by cyclic voltammetry, UV-vis absorption and fluorescence. The PL maximum of copolymers presented obviously red-shift to long wavelength as the feed ratio of EDOT in monomer mixture increased.

Preparation and Characterization of Cefradine/Montmorillionite Composites

2012 ◽  
Vol 560-561 ◽  
pp. 434-437 ◽  
Author(s):  
Lan Wang ◽  
Wen Ji Guo ◽  
Yan Zhao Zhao
Keyword(s):  
Gastric Fluid ◽  
Simulated Gastric Fluid ◽  
X Ray Diffraction ◽  
Simulated Intestinal Fluid ◽  
Solution Intercalation ◽  
Method Of Solution ◽  
Ft Ir ◽  
In The Beginning ◽  
Ft Ir Spectroscopy

The objective of this paper was to prepare the composite of crefradine/montmorillionite in the method of solution intercalation. The drug load and intercalation rate varied with the drug concentration. X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) Spectroscopy, and thermal analysis (TG-DSC) were applied to characterize composite mentioned above. Together with drug release tests, results indicate cefradine intercalated into montmorillionite.The release profiles of cefradine/MMT in simulated gastric fluid (pH 1.2) and simulated intestinal fluid (pH 7.4) at 37°Cduring 10h are shown in Fig. 4. The amount of cefradine in the beginning 2h came up to 35% and 50%, and in the following time, cefradine released slowly. The release behaviors met the requirements of sustained release.

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