Search results for "Absorption"
showing 10 items of 2701 documents
The Be/X-ray binary LS 992/RX J0812.4-3114: Physical parameters and long-term variability
2000
We present the first long-term optical and infrared study of the optical counterpart to the source RX J0812.4-3114, an X-ray pulsar with a Be type companion. During the period covered by the observations the profile of some Balmer lines changed from absorption to emission and back again to absorption. Contemporaneously, the infrared magnitudes varied by more than 0.8 mag. This long-term variability is interpreted as the formation and subsequent dissipation of the Be star's disc. The building up of the disc ended up in an active X-ray state characterised by regular outbursts occurring at 80 day intervals. The overall duration of the formation/dissipation of the disc is found to be < 4.3 year…
Spectroscopic markers of the T-R quaternary transition in human hemoglobin
2004
n questo lavoro, usiamo un protocollo sol-gel per intrappolare e confrontare gli stati quaternari R e T di entrambi i deossigenati (deossiHb) ederivati di ossido di carbonio (HbCO) dell'emoglobina umana. La banda di assorbimento ottico del vicino infrarosso III e lo stretching di CO a infrarossibanda sono utilizzati per rilevare l'effetto della struttura quaternaria sulle proprietà spettrali di deoxyHb e HbCO; confronto con mioglobinaconsente una valutazione dei contributi terziari e quaternari ai turni di banda misurati. La RXLa transizione T è indicata per causare un bluspostamento della banda III di ~ 35 cm?1per deoxyHb e uno spostamento rosso della banda di allungamento CO di soli ~ 0…
New data on the mercury antimony mineral shakhovite: Chemical composition, unit cell and crystal structure
1982
A new investigation of the mercury antimony mineral shakhovite yielded space groupIm witha=4.871(1),b=15.098(3),c=5,433(1) A and β=98.86(2)°. The determination of the crystal structure gave a cell content of Hg8Sb2O12. Since the presence of Hg2-groups indicates that shakhovite is a pure Hg(1) compound and the infrared spectrum shows an absorption band at 3440 cm−1 which is due to the OH-stretching frequency, it is assumed that there are six oxygen atoms and six OH-groups in the unit cell. Thus the chemical formula of shakhovite reads Hg4Sb(OH)3O3 with two formula units per unit cell. The Hg−Hg distance in the Hg2-group is 2.543 A, each mercury atom has a close oxygen neighbour at 2.160 and …
I.R. Experimental studies of dynamical aspects of water structure: Effects of HD substitution and of small solutes
1980
Abstract Results on i.r. absorption spectra of H2O, D2O and electrolytic solutions and their thermal modifications are presented. From the data, some parameters can be obtained which are suitable for a description of dynamical aspects of water structure. Solute induced changes of these parameters provide a quantitative, although phenomenologic description of the water-solute interaction.
Fluoreszenz‐Untersuchungen an styrylsubstituierten Benzolen
1986
Die Fluoreszenz-Abklingzeiten der stilbenartigen Verbindungen 1 – 4 zeigen, das die mittleren Lebensdauern dieser Molekule im elektronisch angeregten Singulettzustand um rund zwei Zehnerpotenzen hoher sind als bei trans-Stilben selbst. Anhand von UV-Absorptions-und Anregungsspektren wird das auf einen neu gefundenen S1-Zustand zuruckgefuhrt, der einem verbotenen Ubergang S0 S1 auf der langwelligen Seite der intensiven Absorption entspricht. Investigations on the Fluorescence of Styryl-substituted Benzenes Fluorescence decay measurements of the stilbene-like compounds 1 – 4 demonstrate that the average lifetimes of these molecules in the electronically excited singlet state are about 102 tim…
Molecular Multi‐Wavelength Optical Anion Sensors
2010
Polychromatic fingerprinting of simple anions (halides, oxo anions) is achieved by employing neutral and charged multicolor fluorescent probes based on ferrocene-spaced dansyl and naphthyl groups (1/1 + ; 2/2 + ). The conformation of the neutral double dye sensor 2 has been elucidated by NMR spectroscopic techniques (in solution), by X-ray crystallography (solid state) and by DFT calculations (gas phase). The double-dye receptors 2/2 + exhibit specific emission responses in the presence of anions X- when excited at the absorption maxima of the dyes (fingerprint).
Influence of Au, Ag, and Cu Adatoms on Optical Properties of TiO2 (110) Surface: Predictions from RT-TDDFT Calculations
2022
This study was financially supported by Flag-ERA JTC To2Dox project (S.P.) and M-ERA-NET2 project SunToChem (E.A.K.). M.G.B. thanks the support from the Program for the Foreign Experts (Grant No. W2017011) offered by Chongqing University of Posts and Telecommunications and the National Foreign Experts Program for “Belt and Road Initiative” Innovative Talent Exchange (Grant No. DL2021035001L), Estonian Research Council grant PUT PRG111, European Regional Development Fund (TK141), NCN project 2018/31/B/ST4/00924. Institute of Solid State Physics, University of Latvia, as the Center of Excellence, has received funding from the European Union’s Horizon 2020 Framework Program H2020-WIDESPREAD-01…
Five-Coordinate Complexes [FeX(depe)2]BPh4, X = Cl, Br: Electronic Structure and Spin-Forbidden Reaction with N2
2002
The bonding of N(2) to the five-coordinate complexes [FeX(depe)(2)](+), X = Cl (1a) and Br (1b), has been investigated with the help of X-ray crystallography, spectroscopy, and quantum-chemical calculations. Complexes 1a and 1b are found to have an XP(4) coordination that is intermediate between square-pyramidal and trigonal-bipyramidal. Mössbauer and optical absorption spectroscopy coupled with angular overlap model (AOM) calculations reveal that 1a and 1b have (3)B(1) ground states deriving from a (xz)(1)(z(2))(1) configuration. The zero-field splitting for this state is found to be 30-35 cm(-1). In contrast, the analogous dinitrogen complexes [FeX(N(2))(depe)(2)](+), X = Cl (2a) and Br (…
Synthesis and characterisation of [(C5Me4R)2NbS2]2M complexes (M = Fe, Co; R = Me, Et) : organometallic tetrathiometalates with niobocene ligands
1996
Abstract Irradiation of Cp 2 ∗ Nb(η 2 S 2 )H (Cp ∗ = C 5 Me 5 ) 1a in the presence of Fe(CO) 5 gives the CO-free complex [Cp 2 ∗ NbS 2 ] 2 Fe 2a . The core of 2a contains an FeS 4 tetrahedron which is ligated by two niobocene ligands as shown by X-ray diffraction analysis. In the reaction of 1a or Cp 2 x Nb(η 2 S 2 )H (CP x = C 5 Me 4 Et) 1b with Co 2 (CO) 8 , compounds 3a and 3b of the same type are formed. Electrochemical studies of 2a and 3a,b show that they undergo three reversible 1e − steps. The oxidation of 3b exerts a considerable influence on its absorption spectrum. A qualitative EHMO analysis is in agreement with a strong delocalisation of electron density over the whole NbS 2 …