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 Influence of isotopic composition of silicon on local vibrational modes of vacancy-oxygen complex

2021 ◽  
pp. 102-110
Author(s):  
Ekaterina A. Tolkacheva ◽  
Vladimir P. Markevich ◽  
Leonid I. Murin
Keyword(s):  
Isotopic Composition ◽  
Room Temperature ◽  
Oxygen Impurity ◽  
Vibrational Modes ◽  
Absorption Bands ◽  
Impurity Atoms ◽  
Oxygen Complex ◽  
Isotopic Shifts ◽  
Oxygen Center ◽  
Local Vibrational Modes

Isotopic composition of natural silicon (28Si (92.23 %), 29Si (4.68 %) and 30Si (3.09 %)) affects noticeably the shape of infrared absorption bands related to the oxygen impurity atoms. The positions of local vibrational modes (LVMs), related to quasimolecules 28Si – 16OS – 29Si and 28Si – 16OS – 30Si (OS – substitutional oxygen atom) have been determined for the absorption spectra measured at Т ≅ 20 K and at room temperature (Т ≅ 300 K). An estimation of the isotopic shifts of corresponding modes in a semi empirical way has been done by the fitting the shape of the experimentally measured absorption band related to the vacancy-oxygen center in irradiated Si crystals. The LVM isotope shifts at Т ≅ 300 K are found to be (2.22 ± 0.25) сm–1 for 28Si – 16OS – 29Si and (4.19 ± 0.80) сm–1 for 28Si – 16OS – 30Si in relation to the most intense band with its maximum at (830.29 ± 0.09) cm–1 due to the vibrations of  28Si – 16OS – 28Si, and the full width at half maximum of the A-center absorption bands is (5.30 ± 0.26) cm–1. At Т ≅ 20 K the corresponding values have been determined as (1.51 ± 0.13); (2.92 ± 0.20); (835.78 ± 0.01) and (2.34 ± 0.03) сm–1. A model for the calculation of isotopic shifts in the considered case has been discussed. From an analysis of the observed isotopic shifts some information about the structure of the vacancy-oxygen complex in silicon at Т ≅ 20 K and at room temperature has been obtained.

Divacancy-Oxygen and Trivacancy-Oxygen Complexes in Silicon: Local Vibrational Mode Studies

2009 ◽  
Vol 156-158 ◽  
pp. 129-134 ◽  
Author(s):  
L.I. Murin ◽  
Bengt Gunnar Svensson ◽  
J. Lennart Lindström ◽  
Vladimir P. Markevich ◽  
Charalamos A. Londos
Keyword(s):  
Fourier Transform ◽  
Room Temperature ◽  
Vibrational Mode ◽  
Clear Correlation ◽  
Interstitial Oxygen ◽  
Infrared Absorption Spectroscopy ◽  
Oxygen Defect ◽  
Absorption Bands ◽  
Local Vibrational Mode ◽  
Oxygen Complexes

Fourier transform infrared absorption spectroscopy was used to study the evolution of multivacancy-oxygen-related defects in the temperature range 200-300 °C in Czochralski-grown Si samples irradiated with MeV electrons or neutrons. A clear correlation between disappearance of the divacancy (V2) related absorption band at 2767 cm-1 and appearance of two absorption bands positioned at 833.4 and 842.4 cm-1 at 20 K (at 825.7 and 839.1 cm-1 at room temperature) has been found. Both these two emerging bands have previously been assigned to a divacancy-oxygen defect formed via interaction of mobile V2 with interstitial oxygen (Oi) atoms. The present study shows, however, that the two bands arise from different defects since the ratio of their intensities depends on the type of irradiation. The 842.4 cm-1 band is much more pronounced in neutron irradiated samples and we argue that it is related to a trivacancy-oxygen defect (V3O) formed via interaction of mobile V3 with Oi atoms or/and interaction of mobile V2 with VO defects.

scholarly journals Absorption and Emission Spectra for C60 Anions

1994 ◽  
Vol 14 (1-3) ◽  
pp. 155-160 ◽  
Author(s):  
Tatsuhisa Kato
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Theoretical Analysis ◽  
Room Temperature ◽  
Emission Spectra ◽  
Mirror Image ◽  
Ir Absorption ◽  
Near Ir ◽  
Laser Experiments ◽  
Ir Bands

Absorption spectra are detected for C60− and C602− produced electrolytically in solution at room temperature. Theoretical analysis of the spectrum of C60− by CNDO/S calculations gives an interpretation of the characteristic near-IR bands, the weak visible bands, and the strong bands in the UV region. The emission spectrum of C60− is a mirror image of the near-IR absorption band, and the detection of the emission reconfirms our original assignment of the absorption spectrum. The nature of the spectrum of C602− is characterized by a similar orbital picture to that of C60−. Further laser experiments of significance are proposed.

scholarly journals Improvement in tropospheric moisture retrievals from VIIRS through the use of infrared absorption bands constructed from VIIRS and CrIS data fusion

2020 ◽  
Author(s):  
E. Eva Borbas ◽  
Elisabeth Weisz ◽  
Chris Moeller ◽  
W. Paul Menzel ◽  
Bryan A. Baum
Keyword(s):  
Absorption Band ◽  
Data Fusion ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Precipitable Water ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Total Precipitable Water ◽  
Upper Tropospheric Humidity ◽  
Operational Data

Abstract. An operational data product available for both the Suomi-NPP and NOAA-20 platforms provides high spatial resolution infrared (IR) absorption band radiances for VIIRS based on a VIIRS+CrIS data fusion method. This study investigates the use of these IR radiances, centered at 4.5, 6.7, 7.3, 9.7, 13.3, 13.6, 13.9, and 14.2 µm, to construct atmospheric moisture products (e.g., total precipitable water and upper tropospheric humidity) and to evaluate their accuracy. Total precipitable water (TPW) and upper tropospheric humidity (UTH) retrieved from hyperspectral sounder CrIS measurements are provided at the associated VIIRS sensor's high spatial resolution (750 m) and are compared subsequently to collocated operational Aqua MODIS and Suomi-NPP VIIRS moisture products. This study suggests that the use of VIIRS IR absorption band radiances will provide continuity with Aqua MODIS moisture products.

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.

Metastable VO2 Complexes in Silicon: Experimental and Theoretical Modeling Studies

2005 ◽  
Vol 108-109 ◽  
pp. 223-228 ◽  
Author(s):  
L.I. Murin ◽  
J. Lennart Lindström ◽  
Vladimir P. Markevich ◽  
I.F. Medvedeva ◽  
Vitor J.B. Torres ◽  
...  
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Interstitial Oxygen ◽  
Vibrational Modes ◽  
Acceptor Level ◽  
Acceptor State ◽  
Metastable Form ◽  
Local Vibrational Modes ◽  
Co Doped

We report on a combined experimental and theoretical study of the metastable form of the vacancy-dioxygen defect in Si labeled VO∗ 2. Important new experimental observations are the detection of mixed local vibrational modes of VO∗ 2 in 16O,18O co-doped samples, the determination of the position of LVM bands for the negatively charged defect, and an assignment of an acceptor level at about Ec − 0.05 eV. Defect energetics, electrical levels and LVM frequencies of the VO∗ 2 complex are also investigated by ab-initio density-functional modeling.We find it to be a bistable defect which accounts well for the experimental data. The metastable form produces an acceptor state at 0.05 eV below Ec, and can be thought of as a VO defect perturbed by interstitial oxygen.

Carrier Doping of Silicon Nanowires Synthesized by Laser Ablation

2006 ◽  
Vol 963 ◽  
Author(s):  
Naoki Fukata ◽  
Naoya Okada ◽  
Satoshi Matsushita ◽  
Takao Tsurui ◽  
Shun Ito ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Silicon Nanowires ◽  
Optical Phonon ◽  
Room Temperature ◽  
Vibrational Modes ◽  
Scattering Measurements ◽  
Doped Silicon ◽  
Phonon Peak ◽  
Local Vibrational Modes ◽  
Carrier Doping

ABSTRACTBoron (B) doped silicon nanowires (SiNWs) were synthesized by laser ablation. Local vibrational modes of B in SiNWs were observed by micro-Raman scattering measurements at room temperature. Broadening due to a coupling between the discrete optical phonon and a continuum of interband hole excitations was also observed in the Si optical phonon peak. This is called Fano broadening. These results prove that B atoms were doped in substitutional sites of crystalline Si core of SiNWs during laser ablation.

scholarly journals Improvement in tropospheric moisture retrievals from VIIRS through the use of infrared absorption bands constructed from VIIRS and CrIS data fusion

2021 ◽  
Vol 14 (2) ◽  
pp. 1191-1203
Author(s):  
E. Eva Borbas ◽  
Elisabeth Weisz ◽  
Chris Moeller ◽  
W. Paul Menzel ◽  
Bryan A. Baum
Keyword(s):  
Absorption Band ◽  
Data Fusion ◽  
Spatial Resolution ◽  
Infrared Imaging ◽  
High Spatial Resolution ◽  
Precipitable Water ◽  
Ir Absorption ◽  
Absorption Bands ◽  
Total Precipitable Water ◽  
Upper Tropospheric Humidity

Abstract. An operational data product available for both the Suomi National Polar-orbiting Partnership (S-NPP) and National Oceanic and Atmospheric Administration-20 (NOAA-20) platforms provides high-spatial-resolution infrared (IR) absorption band radiances for Visible Infrared Imaging Radiometer Suite (VIIRS) based on a VIIRS and Crosstrack Infrared Sounder (CrIS) data fusion method. This study investigates the use of these IR radiances, centered at 4.5, 6.7, 7.3, 9.7, 13.3, 13.6, 13.9, and 14.2 µm, to construct atmospheric moisture products (e.g., total precipitable water and upper tropospheric humidity) and to evaluate their accuracy. Total precipitable water (TPW) and upper tropospheric humidity (UTH) retrieved from hyperspectral sounder CrIS measurements are provided at the associated VIIRS sensor's high spatial resolution (750 m) and are compared subsequently to collocated operational Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) and S-NPP VIIRS moisture products. This study suggests that the use of VIIRS IR absorption band radiances will provide continuity with Aqua MODIS moisture products.

scholarly journals Оптические свойства и механизм образования вакансионно-кислородных комплексов V-=SUB=-2-=/SUB=-O-=SUB=-2-=/SUB=- и V-=SUB=-3-=/SUB=-O-=SUB=-2-=/SUB=- в облученных кристаллах кремния

2018 ◽  
Vol 52 (9) ◽  
pp. 973
Author(s):  
Е.А. Толкачева ◽  
В.П. Маркевич ◽  
Л.И. Мурин
Keyword(s):  
Infrared Absorption ◽  
Vibrational Modes ◽  
Fourier Spectroscopy ◽  
Absorption Bands ◽  
Fast Electrons ◽  
Czochralski Silicon ◽  
Silicon Crystals ◽  
Local Vibrational Modes ◽  
Oxygen Complexes

AbstractThe processes of the formation and annealing of V_ n O_ m ( n , m ≥ 2) vacancy–oxygen complexes in Czochralski silicon crystals irradiated with fast electrons and reactor neutrons have been studied by infrared absorption Fourier spectroscopy. A number of arguments are presented in favor of identification of absorption bands at 829.3 and 844.2 cm^–1 as being related to local vibrational modes of V_2O_2 and V_3O_2 complexes, respectively.

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