Cadmium Diiodide Research Articles

Dimethylaniline-Based Hybrid Compounds of Cadmium Diiodide: Synthesis, Crystal Structure, and Physical Properties

In this work, synthesis, crystal structure, and selected properties of two new organic–inorganic compounds based on cadmium iodide with 2,5- and 2,6-dimethylaniline: CdI2(2,5-DMA)2 1 and CdI2(2,6-DMA)2 2, respectively, were investigated. Both compounds were obtained using the same methodology, and their crystal structures were determined from powder (1) and single-crystal (2) X-ray diffraction experiments. The examined materials crystallize in the noncentrosymmetric space group Fdd2 and contain large polarizable iodine ions and electron-rich aromatic ligands. Second harmonic generation (SHG) tests performed with urea as a reference revealed high SHG efficiency of powdered samples 1 and 2. SHG signals measured for samples 1 and 2 are, respectively, around 10 and 8 times larger than the signal for urea. The experimental part was supplemented with theoretical calculations of the second-order electric susceptibility tensor components, χijk(2). Calculated values of the χ113(2) tensor component around 1.2–1.4 pm·V–1 suggest that both materials are relatively efficient second harmonic generators. Fibrous morphology of the materials was revealed by scanning electron microscopy (SEM), and the observed bending of the fibers suggested their significant flexibility. Samples 1 and 2 were also characterized by spectroscopic techniques (IR, RS, UV–Vis-DRS) and their thermal stability and decomposition rates were researched using XRPD and TG/DSC, revealing that both investigated materials are thermally stable up to around 100 °C.

EMISSION CHARACTERISTICS OF GAS DISCHARGE PLASMA ON MIXTURES OF CADMIUM DIODIDE VAPOR, HELIUM AND XENON

The results of studying the spectral, integral, and resource characteristics of gas-discharge plasma radiation on multicomponent mixtures (cadmium diiodide with helium and xenon atoms) are presented. The creation of a gasdischarge plasma and the excitation of the components of the working mixture were carried out by a pulse-periodic (pulse repetition rate of 18…20 kHz, pulse duration ~ 150 ns) barrier discharge. Radiation in the visible spectrum of exciplex molecules of cadmium monoiodide, cadmium atoms, xenon was detected. The regularities in changes in the emission characteristics of the plasma are established depending on the repetition rate of the pump pulses, the component and quantitative composition of the mixtures. Research data is of interest for creating a gas-discharge source that radiates simultaneously in the violet, green, red, and infrared spectral ranges.

Spectroscopic diagnostics of a high-frequency dielectric barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and small additions of xenon

Diagnostics of the emission spectra of a gas-discharge plasma of a barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and small additions of xenon is carried out. A gas-discharge plasma was created and the components of the working mixture were excited by a high-frequency barrier discharge at a sinusoidal voltage pulse repetition rate of up to 140 kHz. Emission of exciplex molecules of cadmium monoiodide with a maximum emission at a wavelength of λ = 655 nm and xenon iodide with a maximum of radiation at wavelengths λ = 253 and λ = 320 nm, excimer molecules of iodine, lines of atoms of cadmium, iodine, neon and xenon was revealed. It was found that at temperatures of the mixtures under study above 150 0C, the predominance of radiation from exciplex molecules of cadmium monoiodide is observed. The reason for the increased brightness of the emission of exciplex molecules of cadmium monoiodide in mixtures of cadmium diiodide vapor with neon and xenon additive is established. The regularities in the spectral characteristics of radiation in the mixtures under study are discussed. A high-frequency barrier discharge of atmospheric pressure in mixtures of cadmium diiodide vapor with neon and xenon is of interest for creating a multi-wavelength excilamp in the UV and visible spectral ranges

Optical characteristics and parameters of gas discharge plasma on a mixture of cadmium diodide vapor with helium and small addition of nitrogen

Наведено результати дослідження спектральних, інтегральних і ресурсних характеристик випромінювання газорозрядної плазми атмосферного тиску на багатокомпонентних сумішах дийодиду кадмію з гелієм і малої добавки молекулярного азоту. Створення газорозрядної плазми і збудження компонент робочої суміші здійснювалося імпульсно-періодичним (частота проходження імпульсів 18–20 кГц, тривалість імпульсів 150 нс) бар’єрним розрядом. Виявлено випромінювання у видимій області спектру ексиплексних молекул монойодиду кадмію, атомів кадмію. Встановлено закономірності в змінах оптичних характеристик плазми в залежності від частоти проходження імпульсів накачки, компонентного і кількісного складу сумішей. Представлено обговорення результатів досліджень. Дані досліджень представляють інтерес для створення ексиплексних газорозрядних джерел видимого випромінювання з максимумом випромінювання на довжині хвилі λ=650 нм.

Molecular Structure of Monomeric Cadmium-Dihalides, CdCl2, CdBr2, CdF2, CdI2

The geometrical parameters, namely, bond lengths and bond angles of cadmium dihalides were calculated from different levels of computation and experimentally. Several ab initio studies have been carried out. Most of them were assuming linearity for CdCl2. On the other hand, computational studies show that the monomeric cadmium dihalides were assigned linear geometries [1, 2]. In this work we have calculated the equilibrium structure of the Cadmium dihalides using the interionic force model. The computed bond lengths and bond angles are in a good agreement with measured values from electron diffraction (ED) and quantum chemical calculations such as, LDF and QCISD. Supposing linearity of the molecules their 3  bending frequencies were estimated from electron diffraction, except cadmium diiodide molecule that was fitted to 1  mode frequency. We have made use of the simplifying features that have previously been established in similar studies of other ionic compounds which are the transferability of parameters describing the halogen ion [3, 4, 5]. It has been shown that the interionic force model is capable of the molecular structures of cadmium dihalides. Keywords: Cadmium Dihalides, Interionic Force Model, chloride, fluoride, bromide, iodide DOI: 10.7176/JSTR/5-8-10

Synthesis and crystal structure of the coordination compound of cadmium diiodide monohydrate with quinoxaline

The coordination compound [CdI2(Quinox)2(H2O)] has been synthesized by the reaction between CdI2 and quinoxaline (Quinox, C8H6N2) in a water–ethanol (1: 5) solution, and its crystal structure has been determined. Crystals are orthorhombic, space group Pnma, a = 13.069(1) A, b = 15.218(1) A, c = 9.423(1) A, V = 1874.0(3) A3, ρcalcd = 2.284 g/cm3, Z = 4. The cadmium atom is located in the plane m and has a distorted trigonal bipyramidal coordination; two crystallographically nonequivalent iodine atoms and the O(H2O) atom are in the equatorial plane, and the two nitrogen atoms of two symmetric Quinox ligands are in the axial vertices (Cd(1)–N(1), 2.490(3) × 2 A; Cd(1)–I(1), 2.7533(6) A; Cd(1)–I(2), 2.7280(7) A). The angles at the cadmium atom are 157.1 (2)° between the axial nitrogen atoms and 107.9(1)°–130.8(1)° between the equatorial atoms (maximum value corresponds to the ICdI angle). The complexes are linked into supramolecular strips via O–H…N hydrogen bonds.

Cadmium and Mercury Complexes Containing Trinuclear Titanium Imido‐Nitrido Metalloligands

Several heterometallic nitrido complexes have been prepared from the reaction of the trinuclear imido-nitrido titanium complex [{Ti(η5-C5Me5)(μ-NH)}3(μ3-N)] (1) with cadmium and mercury derivatives. Treatment of 1 with cadmium dichloride or cadmium diiodide in toluene afforded the adducts [X2Cd{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] [X = Cl (2), I (3)]. Complex 2 reacted with lithium reagents [LiR] in toluene to give the cube-type derivatives [RCd{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}] [R = CH2SiMe3 (4), C≡CSiMe3 (5), C5H4(SiMe3) (6), N(SiMe3)2 (7)]. The amido complex 7 reacted with 1 equiv. of 1 to give the corner-shared double-cube complex [Cd{(μ3-N)(μ3-NH)2Ti3(η5-C5Me5)3(μ3-N)}2] (8) by means of bis(trimethylsilyl)amine elimination. Treatment of 1 with mercury(II) iodide in toluene gave the adduct [I2Hg{(μ3-NH)3Ti3(η5-C5Me5)3(μ3-N)}] (9), which reacted with [K{N(SiMe3)2}] to afford [Hg{(μ3-N)2Ti3(η5-C5Me5)3(μ-NH)(μ3-N)}]2 (10) through the amido mercury intermediate [{(Me3Si)2N}Hg{(μ3-N)Ti3(η5-C5Me5)3(μ-NH)2(μ3-N)}] (11). Compound 11 and the analogous alkyl derivative [(Me3SiCH2)Hg{(μ3-N)Ti3(η5-C5Me5)3(μ-NH)2(μ3-N)}] (12) were characterised by NMR spectroscopy upon the treatment of 1 with [Hg{N(SiMe3)2}R] [R = N(SiMe3)2, CH2SiMe3]. Complex [Hg{(μ3-N)Ti3(η5-C5Me5)3(μ-NH)2(μ3-N)}2] (13), with one bridging mercury atom between two titanium trinuclear systems, was obtained upon treatment of HgI2 with the potassium derivative [K(μ4-N)(μ3-NH)2{Ti3(η5-C5Me5)3(μ3-N)}]2. Complexes 3, 5 and 8 were characterised by single-crystal X-ray diffraction analysis.

Bis(diethylenetriamine)cadmium(II) diiodide

In the title compound, [Cd(dien)2]I2, where dien = diethyl­enetriamine (C4H13N3), the CdII ion is in a distorted octa­hedral coordination environment. In the crystal structure, inter­molecular N—H⋯I hydrogen bonds link cations and anions into a three-dimensional network.

Spectral characteristics of a barrier discharge in cadmium dihalide vapor-inert gas mixtures

Spectral characteristics of a barrier-discharge plasma produced in atmospheric-pressure mixtures of cadmium diiodide and cadmium dibromide vapors with neon, krypton, and xenon at a repetition rate of sine voltage pulses up to 130 kHz are studied. The emission from the discharge is studied within the spectral range 200–900 nm with a resolution of 0.05 nm. Emission of exciplex molecules CdI(B → X) and CdBr(C, B → X), and cadmium and inert gas atoms is revealed, as well as emission of exciplex molecules XeI(B → X, A) and XeBr(B → X, A) in xenon-containing mixtures. The emission of xenon halides prevails in the spectra at a mixture temperature up to 200°C. With a further temperature increase, the emission of cadmium halides becomes dominating. It is ascertained that the most intense emissions of CdI(B → X) and CdI2/CdBr2/Xe/Kr and CdBr(B → X) molecules are observed, respectively, in CdI2/CdBr2/Xe/Kr and CdI2/CdBr2/Xe mixtures. The cadmium dihalide-inert gas mixtures are of interest for the use as a radiating gas in a multiwavelength and broadband excilamp emitting in the UV and visible spectral ranges.

Spectroscopic diagnostics of barrier-discharge plasma in mixtures of cadmium diiodide vapor with gases

The spectral characteristics of the emission of atmospheric-pressure gas-discharge plasma in mixtures of cadmium diiodide vapor with gases (Ne, Ar, Kr, Xe, and N2) were investigated along with the time characteristics of the voltage and current. The gas-discharge plasma was produced and excited by a barrier discharge at a repetition rate of sine voltage pulses of up to 140 kHz. The discharge emission was analyzed in the spectral range 200–900 nm with a high resolution (0.05 nm). Radiation from exciplex CdI(B-X) molecules and excimer I2* molecules was revealed, as well as the atomic lines of cadmium, iodine, and inert gases. In a mixture with xenon, radiation from exciplex molecules XeI(B-X, B-A) was also found. This radiation prevailed in the spectra at mixture temperatures up to 150°C. The further increase of the temperature leads to the prevalence of the CdI(B-X) radiation. It was found that the most intense CdI(B-X) radiation is observed in mixtures CdI2/Xe(N2)/Ne. Regularities in the spectral characteristics of the emission of the gas-discharge plasma are discussed.

Reactive and charge transfer processes in electronically inelastic collisions between ground state cadmium(II) diiodide molecules and lithium ions in the 0.10–4.00 keV energy range by crossed molecular beams

Charge transfer processes leading to different excited states of lithium atoms in the collision system CdI 2 ( 1 Σ g + ) + Li + ( 1 S g ) have been studied by crossed molecular beams techniques. Absolute emission cross-sections for the different exit channels have been measured as a function of the collision energy in the 0.10–4.00 keV energy range. Also the excitation function for the collision induced dissociation process leading to Cd (5 3P 1) has been obtained. Ab initio structure calculations performed at the second order Möller–Plesset level furnish a picture of the non-adiabatic effects for some of the electron transfers experimentally observed.

Bis(alkylcyclopentadienyl)cadmium Complexes and Alkylcyclopentadienyl(mesityl)cadmium: Synthesis and Structure

Cadmium diiodide tetrahydrofuran adduct was prepared from the elements in tetrahydrofuran and converted to bis(alkylcyclopentadienyl)cadmium complexes with sodium tetraisopropylcyclopentadienide or sodium l,2,4-tri(tert-butyl)cyclopentadienide. Both products are fluxional in solution, and for bis{tri-(tert-butyl)cyclopentadienyl}cadmium η 1 ,η 1 -bonding has been observed in the solid state. With 1 equiv each of sodium l,2,4-tri(tert-butyl)cyclopentadienide and mesitylmagnesium bromide the aryl complex mesityl{tri(tert-butyl)cyclopentadienyl}cadmium could be obtained from cadmium diiodide in moderate yield.

An excimer source of visible light

A gas-discharge excimer radiation source in the visible spectral region has been developed on the basis of a mixture of cadmium diiodide vapors and helium excited by a repetitively pulsed barrier discharge. The source radiation spectrum consists mainly of superimposed spectral bands of emission of cadmium iodide in the range 470–700 nm. The mean radiation power from the source surface (114.5 cm2) is 55 W, the pulse power is 105 kW, and the efficiency is ∼10%. Approximately 90% of the radiation power is concentrated in the red region, which is much higher than in high-pressure sodium lamps at comparable energies deposited into the working mixtures. Such sources can be used to efficiently control photosynthesis and the growth and development of plants and algae.

Optical characteristics of barrier discharge plasma based on mixtures of cadmium diiodide vapors with gases

The spectral, integrated, and working life characteristics of the radiation from atmospheric pressure gas discharge plasma based on multicomponent mixtures (cadmium diiodide with helium and small admixtures of molecular nitrogen and xenon) are analyzed. A pulsed barrier discharge (pulse repetition rates 5000, 5500, and 6000 Hz; pulse duration ∼150 ns) is used both to produce the gas discharge plasma and to excite the components of the working mixture. Visible radiation is detected from excimer molecules of cadmium monoiodide and cadmium, xenon, and krypton atoms. Regular features are found in the variations of optical plasma characteristics with pumping pulse repetition rate and with component and quantitative mixture composition.

Influence of adsorption on the transverse photovoltage arising in cadmium diiodide crystals under X-ray irradiation

The influence of a gas atmosphere (O2 or air) on the transverse photovoltage (TPV) induced by X-ray irradiation in CdI2 specimens is studied. It is shown that the TPV measured at 295 K in a vacuum grows almost linearly with X-ray dose rate R. In a gas atmosphere, the TPV is of opposite sign and tends to saturation when R exceeds 200 R/min. After evacuation of the system, the TPV value increases, attains a maximum, and then abruptly drops (changing sign) to the initial “vacuum” value. Based on the results of this study and published data, it is shown that such behavior of the TPV in CdI2 is related to X-ray-stimulated chemisorption proceeding by the acceptor mechanism.

Inelastic Collisions of Slow Electrons with Cadmium(II) Iodide Molecules

Inelastic collisions of electrons with cadmium diiodide molecules were studied by the extended crossed-beam technique. Cross sections for dissociative excitation of spectral lines of the excited atom and the singly charged ion of cadmium were measured at an incident electron energy of 30 eV. The obtained results are compared with data on direct excitation cross sections in e–Cd collisions.

Molecular structure of cadmium diiodide from combined electron diffraction and vibrational spectroscopic analysis

The molecular geometry and molecular dynamics of CdI 2 was studied by joint electron diffraction/vibrational spectroscopic analysis. The thermal average ( r g) bond length is 2.582 ± 0.005 Å. The equilibrium configuration of the molecule is linear and the equilibrium bond length is estimated to 2.570±0.006 Å.

The enthalpy increments of solid and liquid cadmium di-iodide

The enthalpy increments of solid and liquid cadmium di-iodide have been measured from 477 to 859 K in a diphenyl ether drop calorimeter. In addition, differential scanning calorimetry revealed no indications of phase transformations apart from the solid-liquid transition. From these data thermodynamic functions for the solid and liquid phases have been calculated.

Photodissociation of Cadmium Diiodide

Photodissociation of cadmium diiodide was studied. The nascent vibrational distribution of CdI(X2Σ) on the photodissociation of CdI2 at 308 nm was determined by the laser‐induced fluorescence (LIF) technique. The temporal variation in the density of CdI(X2Σ) radicals was monitored and it was shown that second‐order recombination reactions were important under our experimental conditions. Both the ground and the highly excited states of cadmium atoms were generated on photodissociation of CdI2. The multiphoton absorption process for the production of highly excited Cd atoms is discussed.