scholarly journals FTIR study of carbon monoxide adsorption on ion-exchanged X, Y and mordenite type zeolites

2003 ◽  
Vol 68 (4-5) ◽  
pp. 409-416 ◽  
Author(s):  
Vesna Rakic ◽  
Vera Dondur ◽  
Radmila Hercigonja
Keyword(s):  
Carbon Monoxide ◽  
Fourier Transform ◽  
Transition Metal ◽  
Room Temperature ◽  
Ir Absorption ◽  
Transition Metal Cation ◽  
Absorption Bands ◽  
Ftir Study ◽  
Adsorption Of Co ◽  
Charge Balancing

In this work Fourier transform infrared (FTIR) study has been applied to study the adsorption of carbon monoxide on transition metal (Mn2+, Co2 Ni2+) ion-exchanged zeolites type Y, X and mordenites. The adsorption of CO at room temperature produces overlapping IR absorption bands in the 2120?2200 cm-1 region. The frequency of the band around 2200 cm-1 is found to be dependent not only on the charge-balancing transition metal cation but also on the framework composition. The frequencies of the band near 1600 cm-1 was found to be dependent on the Si/Al ratio of the investigated zeolites.

scholarly journals Local vibrational modes of vacancy-oxygen-related complexes at room temperature

2020 ◽  
Vol 56 (4) ◽  
pp. 480-487
Author(s):  
E. A. Tolkacheva ◽  
V. P. Markevich ◽  
L. I. Murin
Keyword(s):  
Absorption Band ◽  
Room Temperature ◽  
Clear Correlation ◽  
Ir Absorption ◽  
Oxygen Impurity ◽  
Interstitial Oxygen ◽  
Vibrational Modes ◽  
Oxygen Defect ◽  
Absorption Bands ◽  
Local Vibrational Modes

The isotopic content of natural silicon (28Si (92.23 %), 29Si (4.68 %) и 30Si (3.09 %)) affects noticeably the shape of IR absorption bands related to the oxygen impurity atoms. In the present work an attempt is undertaken to determine the positions of local vibrational modes (LVMs), related to quasimolecules 28Si16OS29Si and 28Si16OS30Si (OS – substitutional oxygen atom), for the absorption spectra measured at room temperature. An estimation of the isotopic shifts of corresponding modes is done by fitting the shape of the experimentally measured absorption band related to the vacancy–oxygen center in irradiated Si crystals. The LVM isotope shifts are found to be equal 2,2 ± 0.25 cm–1 for 28Si-16OS29Si and 4,3 ± 0,9 см–1 for 28Si-16OS30Si in relation to the basic band due to 28Si-16OS28Si, and the full width at half maximum of the A-center absorption band (28Si-16OS28Si) is 5,3 ± 0.25 cm–1. By means of infrared absorption spectroscopy a clear correlation between the disappearance of the divacancy (V2) in the temperature range 200–275 ºС and appearance of two absorption bands with their maxima at 825.8 and 839.2 cm–1 in irradiated oxygen-rich Si crystals is found. The band positioned at 825.8 cm–1 is assigned to a divacancy-oxygen defect V2O formed via an interaction of mobile V2 with interstitial oxygen (Oi ) atoms. The 839.2 cm–1 band is much more pronounced in neutron irradiated samples as compared to samples irradiated with electrons. We argue that it is related to a trivacancy–oxygen defect (V3O) formed via an interaction of mobile V3 with Oi atoms.

scholarly journals Определение коэффициента экстинкции моноксида углерода, адсорбированного на диоксиде титана

2021 ◽  
Vol 129 (11) ◽  
pp. 1400
Author(s):  
К.М. Буланин ◽  
А.Ю. Михелева ◽  
Д.Н. Щепкин ◽  
А.В. Рудакова
Keyword(s):  
Experimental Data ◽  
Carbon Monoxide ◽  
Infrared Spectroscopy ◽  
Extinction Coefficient ◽  
Room Temperature ◽  
Heterogeneous Systems ◽  
Tio2 Anatase ◽  
Weak Adsorption ◽  
Adsorption Of Co ◽  
Logarithmic Law

The adsorption of carbon monoxide on the TiO2 (anatase) surface at room temperature was studied by infrared spectroscopy and volumetry. The experimental data obtained indicate weak adsorption of CO molecules on the exponentially heterogeneous surface. The adsorption heat decreases according to the logarithmic law in the coverage range of 0.002-0.03. The extinction coefficient of adsorbed CO for the heterogeneous CO/TiO2 system is calculated using the Bouguer-Lambert-Beer law with correction for the Lorenz field taken into account. The conditions for the applicability of the Bouguer-Lambert-Beer's law for the study of heterogeneous systems are discussed.

Preparation and Properties of Gadolinium Homoleptic Double-and Triple-Decker Complexes Containing Tetrabenzoporphyrin Ligand

2013 ◽  
Vol 750-752 ◽  
pp. 1816-1821
Author(s):  
Qi Feng Liu
Keyword(s):  
Room Temperature ◽  
Spin Exchange ◽  
Spectroscopic Studies ◽  
Magnetic Interactions ◽  
Antiferromagnetic Coupling ◽  
Ir Absorption ◽  
Magnetic Studies ◽  
Absorption Bands ◽  
Near Ir ◽  
Sandwich Type

Two novel gadolinium sandwich-type complexes containing tetrabenzoporphyrin (TBP) ligands-Gd (TBP)2and Gd (TBP)3were prepared from porphyrin 1 and Gd (acac)3. nH2O under Ar by boiling 1, 2, 4-Tcb for 15~17h and 45~48 h respectively. Their structures are characterized by Uv-Vis, HR-MS and IR. The spectroscopic studies show that their longest-wavelength visible and near-IR absorption bands are obviously red-shifted due to the extension of the π conjugated systems in the TBP ring. The magnetic studies indicate that the observed value of χMT for Gd (TBP)2is close to the combined value of Gd (III) and porphyrin radical anion at room temperature and that antiferromagnetic interaction possibly results from the intramolecular spin exchange between the porphyrin π-radical electron and that the gadolinium f unpaired electrons dominates its magnetic properties over the whole temperature range while there is no magnetic interactions between two Gd (III) ions in Gd (TBP)3in the range from room temperature down to 20K and very weak antiferromagnetic coupling exsits between two Gd (III) ions below 20K.

Material synthesis and infrared optical properties of transition metal doped binary and ternary II-VI semiconductors

2005 ◽  
Vol 891 ◽  
Author(s):  
Uwe Hömmerich ◽  
Ei Ei Nyein ◽  
Sudhir B. Trivedi ◽  
Althea G. Bluiett
Keyword(s):  
Transition Metal ◽  
Infrared Region ◽  
Ir Absorption ◽  
Carrier Injection ◽  
Material Synthesis ◽  
Absorption Bands ◽  
Cadmium Chalcogenides ◽  
Cr Concentration ◽  
Metal Doped ◽  
Co Doped

ABSTRACTWe report on the material preparation and optical characterization of transition metal (Cr, Co) doped ternary cadmium chalcogenides for possible applications in mid-infrared (MIR) light source development. Cr2+ doped II-VI's (e.g. ZnSe, ZnS) have received significant attention for MIR solid-state laser development in the 2-3 μm region. Transition metal (TM) doped II-VI thin films are also currently being studied for the development of broadly tunable MIR sources pumped through electrical carrier-injection. In this paper, we present results of the material synthesis and IR spectroscopy of several Cr and Co doped cadmium chalcogenides including CdTe, CdMnTe, CdZnTe, CdMgTe, CdCaTe, and CdSrTe. Following the synthesis and purification of undoped II-VI materials, TM doping was achieved during in-situ Bridgman growth or through a thermal diffusion process. The Cr2+ doped II-VI materials were characterized by broad IR absorption bands centered at ∼1800–1900 nm and MIR emission extending from ∼2000–3500 nm. The emission lifetimes varied between 1-5 μs, depending on the Cr concentration and host composition. Co2+ doped cadmium chalcogenides exhibited several absorption bands in the infrared region and broad emission extending from ∼3-5 μm. Compared to Cr2+ doped II-VI's, the emission from Co2+ doped chalcogenides was significantly quenched at room-temperature due to the onset of non-radiative relaxations.

scholarly journals An approach to retrieve information on the carbonyl fluoride (COF<sub>2</sub>) vertical distributions above Jungfraujoch by FTIR multi-spectrum multi-window fitting

2009 ◽  
Vol 9 (1) ◽  
pp. 3167-3205
Author(s):  
P. Duchatelet ◽  
E. Mahieu ◽  
R. Ruhnke ◽  
W. Feng ◽  
M. Chipperfield ◽  
...  
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
Linear Trend ◽  
Lower Boundary ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Data Set ◽  
Fitting Procedure ◽  
Significant Bias ◽  
Carbonyl Fluoride

Abstract. We present an original multi-spectrum fitting procedure to retrieve volume mixing ratio (VMR) profiles of carbonyl fluoride (COF2) from ground-based high resolution Fourier transform infrared (FTIR) solar spectra. The multi-spectrum approach consists of simultaneously combining, during the retrievals, all spectra recorded consecutively during the same day and with the same resolution. Solar observations analyzed in this study with the SFIT-2 v3.91 fitting algorithm correspond to more than 2900 spectra recorded between January 2000 and December 2007 at high zenith angles, with a Fourier Transform Spectrometer operated at the high-altitude International Scientific Station of the Jungfraujoch (ISSJ, 46.5° N latitude, 8.0° E longitude, 3580 m altitude), Switzerland. The goal of the retrieval strategy described here is to provide information about the vertical distribution of carbonyl fluoride. The microwindows used are located in the ν1 or in the ν4 COF2 infrared (IR) absorption bands. Averaging kernel and eigenvector analysis indicates that our FTIR retrieval is sensitive to COF2 inversion between 17 and 30 km, with the major contribution to the retrieved information always coming from the measurement. Moreover, there was no significant bias between COF2 partial columns, total columns or VMR profiles retrieved from the two bands. For each wavenumber region, a complete error budget including all identified sources has been carefully established. In addition, comparisons of FTIR COF2 17–30 km partial columns with KASIMA and SLIMCAT 3-D CTMs are also presented. If we do not notice any significant bias between FTIR and SLIMCAT time series, KASIMA COF2 17–30 km partial columns are lower of around 25%, probably due to incorrect lower boundary conditions. For each times series, linear trend estimation for the 2000–2007 time period as well as a seasonal variation study are also performed and critically discussed. We further demonstrate that all time series are able to reproduce the COF2 seasonal cycle, which main seasonal characteristics deduced from each data set agree quite well.

scholarly journals An approach to retrieve information on the carbonyl fluoride (COF<sub>2</sub>) vertical distributions above Jungfraujoch by FTIR multi-spectrum multi-window fitting

2009 ◽  
Vol 9 (22) ◽  
pp. 9027-9042 ◽  
Author(s):  
P. Duchatelet ◽  
E. Mahieu ◽  
R. Ruhnke ◽  
W. Feng ◽  
M. Chipperfield ◽  
...  
Keyword(s):  
Time Series ◽  
Fourier Transform ◽  
Linear Trend ◽  
Meteorological Data ◽  
Lower Boundary ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Data Set ◽  
Significant Bias ◽  
Carbonyl Fluoride

Abstract. We present an original multi-spectrum fitting procedure to retrieve volume mixing ratio (VMR) profiles of carbonyl fluoride (COF2) from ground-based high resolution Fourier transform infrared (FTIR) solar spectra. The multi-spectrum approach consists of simultaneously combining, during the retrievals, all spectra recorded consecutively during the same day and with the same resolution. Solar observations analyzed in this study with the SFIT-2 v3.91 fitting algorithm correspond to more than 2900 spectra recorded between January 2000 and December 2007 at high zenith angles, with a Fourier Transform Spectrometer operated at the high-altitude International Scientific Station of the Jungfraujoch (ISSJ, 46.5° N latitude, 8.0° E longitude, 3580 m altitude), Switzerland. The goal of the retrieval strategy described here is to provide information about the vertical distribution of carbonyl fluoride. The microwindows used are located in the ν4 or in the ν4 COF2 infrared (IR) absorption bands. Averaging kernel and eigenvector analysis indicates that our FTIR retrieval is sensitive to COF2 inversion between 17 and 30 km, with the major contribution to the retrieved information always coming from the measurement. Moreover, there was no significant bias between COF2 partial columns, total columns or VMR profiles retrieved from the two bands. For each wavenumber region, a complete error budget including all identified sources has been carefully established. In addition, comparisons of FTIR COF2 17–30 km partial columns with KASIMA and SLIMCAT 3-D CTMs are also presented. If we do not notice any significant bias between FTIR and SLIMCAT time series, KASIMA COF2 17–30 km partial columns are lower of around 25%, probably due to incorrect lower boundary conditions. For each times series, linear trend estimation for the 2000–2007 time period as well as a seasonal variation study are also performed and critically discussed. For FTIR and KASIMA time series, very low COF2 growth rates (0.4±0.2%/year and 0.3±0.2%/year, respectively) have been derived. However, the SLIMCAT data set gives a slight negative trend (−0.5±0.2%/year), probably ascribable to discontinuities in the meteorological data used by this model. We further demonstrate that all time series are able to reproduce the COF2 seasonal cycle, which main seasonal characteristics deduced from each data set agree quite well.

scholarly journals Calibrations coefficients for determination of concentrations of vacancy-oxygen-related complexes and oxygen dimer in silicon by means of infrared absorption spectroscopy

2021 ◽  
Vol 66 (2) ◽  
pp. 227-233
Author(s):  
I. F. Medvedeva ◽  
V. P. Markevich ◽  
K. A. Talkachova ◽  
A. A. Fadzeyeva ◽  
D. N. Zhdanovich ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Infrared Absorption ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Calibration Coefficient ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Oxygen Precipitates ◽  
Calibration Coefficients

Vacancy-oxygen complexes VnOm (n, m ≥ 1) in crystalline silicon are nucleation centers for oxygen precipitates, which are widely used as internal getters in modern technologies of production of silicon-based electronic devices and integrated circuits. For the controllable formation of oxygen precipitates in Si crystals in the technology processes the methods of determination of concentrations of the VnOm complexes are required. The aim of the present work was to find values of the calibration coefficients for determination of concentrations of the VnOm defects in Si from intensities of infrared (IR) absorption bands associated with the local vibrational modes (LVM) of these complexes. A combined electrical (Hall effect) and optical (IR absorption) study of vacancy-oxygen defects in identical silicon crystals irradiated with 6 MeV electrons was carried out. Based on the analysis of the data obtained, the values of the calibration coefficient for the determination of concentration of the vacancy-oxygen (VO) complex in silicon by the infrared absorption method were established: for measurements at room temperature (RT) – NVO = 8.5 · 1016 · αVO-RT cm–3, in the case of low-temperature (LT, Т ≡ 10 K) measurements – NVO = 3.5 · 1016 · αVO-LT cm–3, where αVO-RT(LT) are absorption coefficients in maxima of the LVM bands due to the VO complex in the spectra measured at corresponding temperatures. Calibration coefficients for the determination of concentrations of other VnOm (VO2, VO3, VO4, V2O and V3O) complexes and the oxygen dimer (O2) from an analysis of infrared absorption spectra measured at room temperature have been also determined.

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