Iodine Dimer Research Articles

A formula of Tietz potential parameters and applying for scandium iodine, nitrogen iodine, rubidium hydride, nitrogen, and carbon monoxide molecules

Tietz potential has several applications in the study of diatomic molecules in the discussion of vibrational states, especially in the quantum mechanics studies of the oscillations. Tietz potential has multiple forms; one of the Tietz potential forms has four parameters of the spectroscopic fitting. The spectroscopic fitting parameters of the Tietz potential are the Tietz potential equilibrium bond length, the Tietz potential depth, the width of the potential, and the parameter that controls the values as ratio of the depth of the well. This work focuses on finding a formula between the four parameters of the spectroscopic fitting employing some of principles of the statistical mechanics. Based on the derived formula, we discuss the relationship of the equilibrium bond length of Tietz potential interaction as a function to the absolute temperature. Based on this discussion, the equilibrium bond length of Tietz potential interaction varies slowly with absolute temperature. Besides, equilibrium bond length of Tietz potential varies linearly with the radius of the particles of the system. Also, the equilibrium bond length of Tietz potential varies with the Tietz potential depth, the width parameter of Tietz potential, and the fourth parameter of the Tietz potential. The formula of the Tietz interaction is applied to five different dimers or molecules. The five considered molecules are nitrogen dimer, scandium iodine dimer, nitrogen iodine dimer, rubidium hydride dimer, and carbon monoxide molecule. Generally, it is found that the equilibrium bond length of Tietz potential interaction values varies from 1 to 5 Å for different absolute temperature intervals. Besides, it is found that the scandium iodine dimer has the largest value of the equilibrium bond length of Tietz potential interaction, while carbon monoxide dimer has the lowest value of the equilibrium bond length of Tietz potential interaction. Generally, the derived formula of the four parameters of the spectroscopic fitting of Tietz potential can be applied for multiple molecules and dimers.

Energies of some halogen molecules for the improved Tietz potential model

A solution of the radial Schrödinger equation for an improved Tietz potential function was obtained using the concept of the supersymmetric approach. The energy equation obtained for the non-relativistic wave equation was used to generate numerical values for chlorine dimer, iodine dimer and bromine dimer with the aid of their respective spectroscopic constants. The calculated results were compared with RKR values for each of the molecules. The calculated results were found to be in excellent agreement with the RKR values.

The Interplay Between Lead Vacancy and Water Rationalizes the Puzzle of Charge Carrier Lifetimes in CH3 NH3 PbI3 : Time-Domain Ab Initio Analysis.

The perovskite CH3 NH3 PbI3 excited-state lifetimes exhibit conflicting experimental results under humid environments. Using ab initio nonadiabatic (NA) molecular dynamics, we demonstrate that the interplay between lead vacancy and water can rationalize the puzzle. The lead vacancy reduces NA coupling by localizing holes, slowing electron-hole recombination. By creating a deep electron trap state, the coexistence of a neutral lead vacancy and water molecules enhances NA coupling, accelerating charge recombination by a factor of over 3. By eliminating the mid-gap state by accepting two photoexcited electrons, the negatively charged lead vacancy interacting with water molecules increases the carrier lifetime over 2 times longer than in the pristine system. The simulations rationalize the positive and negative effects of water on the solar cell performance exposure to humidity.

Structural Distortions and Charge Density Waves in Iodine Chains Encapsulated inside Carbon Nanotubes.

Atomic chains are perfect systems for getting fundamental insights into the electron dynamics and coupling between the electronic and ionic degrees of freedom in one-dimensional metals. Depending on the band filling, they can exhibit Peierls instabilities (or charge density waves), where equally spaced chain of atoms with partially filled band is inherently unstable, exhibiting spontaneous distortion of the lattice that further leads to metal-insulator transition in the system. Here, using high-resolution scanning transmission electron microscopy, we directly image the atomic structures of a chain of iodine atoms confined inside carbon nanotubes. In addition to long equidistant chains, the ones consisting of iodine dimers and trimers were also observed, as well as transitions between them. First-principles calculations reproduce the experimentally observed bond lengths and lattice constants, showing that the ionic movement is largely unconstrained in the longitudinal direction, while naturally confined by the nanotube in the lateral directions. Moreover, the trimerized chain bears the hallmarks of a charge density wave. The transition is driven by changes in the charge transfer between the chain and the nanotube and is enabled by the charge compensation and additional screening provided by the nanotube.

Structural and spectroscopic studies of iodine dimer radical anion hydrated clusters: an approach using a combination of stochastic and quantum chemical methods

Structures of I2(−)(H2O)5 clusters after evaluation by simulated annealing and subsequent DFT calculation respectively.

Atomic Structures of CH3NH3PbI3 (001) Surfaces

We report on the atomic structures of methylammonium (MA) lead iodide (CH3NH3PbI3) perovskite surfaces, based on a combined scanning tunneling microscopy and density functional theory calculation study. A reconstructed surface phase with iodine dimers, coexisting with the pristine zigzag phase, was found at the MA-iodine-terminated (001) surfaces of the orthorhombic perovskite films grown on Au(111) surfaces. The reorientation of surface MA dipoles, which strengthens the interactions with surface iodine anions, resulting in a slight energy reduction of 34 meV per unit cell, is responsible for the surface iodine dimerization. According to our calculation, the surface MA dipoles weaken the surface polarity and are therefore considered to be stabilizing the surface structures.

I + (H2O)2 → HI + (H2O)OH Forward and Reverse Reactions. CCSD(T) Studies Including Spin-Orbit Coupling.

The potential energy profile for the atomic iodine plus water dimer reaction I + (H2O)2 → HI + (H2O)OH has been explored using the "Gold Standard" CCSD(T) method with quadruple-ζ correlation-consistent basis sets. The corresponding information for the reverse reaction HI + (H2O)OH → I + (H2O)2 is also derived. Both zero-point vibrational energies (ZPVEs) and spin-orbit (SO) coupling are considered, and these notably alter the classical energetics. On the basis of the CCSD(T)/cc-pVQZ-PP results, including ZPVE and SO coupling, the forward reaction is found to be endothermic by 47.4 kcal/mol, implying a significant exothermicity for the reverse reaction. The entrance complex I···(H2O)2 is bound by 1.8 kcal/mol, and this dissociation energy is significantly affected by SO coupling. The reaction barrier lies 45.1 kcal/mol higher than the reactants. The exit complex HI···(H2O)OH is bound by 3.0 kcal/mol relative to the asymptotic limit. At every level of theory, the reverse reaction HI + (H2O)OH → I + (H2O)2 proceeds without a barrier. Compared with the analogous water monomer reaction I + H2O → HI + OH, the additional water molecule reduces the relative energies of the entrance stationary point, transition state, and exit complex by 3-5 kcal/mol. The I + (H2O)2 reaction is related to the valence isoelectronic bromine and chlorine reactions but is distinctly different from the F + (H2O)2 system.

ChemInform Abstract: Phenol and Aniline Oxidative Coupling with Alkenes by Using Hypervalent Iodine Dimer for the Rapid Access to Dihydrobenzofurans and Indolines.

AbstractThe highly reactive hypervalent iodine dimer [Ph(CF3COO)I]‐O‐[I(OCOCF3)Ph] is shown to promote the oxidative phenolic coupling with styrenes to afford different benzofuran derivatives.

Phenol and Aniline Oxidative Coupling with Alkenes by Using Hypervalent Iodine Dimer for the Rapid Access to Dihydrobenzofurans and Indolines

The highly reactive hypervalent iodine dimer [Ph(CF3COO)I]-O-[I(OCOCF3)Ph] is shown to promote the oxidative phenolic coupling with styrenes to afford different benzofuran derivatives.

Quantum Chemical Study on UV−vis Spectra of Microhydrated Iodine Dimer Radical Anion

UV-vis spectral properties of I(2)(*-).nH(2)O systems are reported based on ab initio quantum chemical calculations. Second order Moller-Plesset perturbation theory is applied for geometry search and time dependent density functional theory is applied to study excited state properties. Relativistic corrections are considered for all the calculations. Geometry search is carried out applying simulated annealing combined with Monte Carlo sampling method. Strong optical absorption band of these hydrated clusters, I(2)(*-).nH(2)O in the UV-vis region is assigned to sigma(g) --> sigma(u)* type valence electron transition in contrast to charge transfer to solvent spectra in I(-).nH(2)O systems. Simulated optical absorption profile of I(2)(*-).8H(2)O system is in excellent agreement with the reported aqueous phase spectrum of iodine dimer radical anion.

Vertical detachment energy of I2•−⋅nCO2 clusters (n=1–8): Experiment versus theory

We report vertical detachment energy (VDE) of I(2) (-)nCO(2) clusters (n=1-8) based on first principle calculations with atomic basis functions. Calculated VDE values of these solvated clusters are in excellent agreement with the reported measured values following photoelectron spectroscopy of size selected I(2) (-)nCO(2) clusters. Bulk VDE of iodine dimer radical anion in solvent CO(2) is predicted as 5.29 eV applying a simple model of extrapolation.

Study on sublimation of solid electrolyte (AgI)0.5‐(AgPO3)0.5with Knudsen effusion mass spectrometry

Knudsen high-temperature mass spectrometry was used to study the process of sublimation of a solid electrolyte (AgI)(0.5-)(AgPO(3))(0.5). Monoatomic iodine ions were found to be the dominant species in the electron ionization mass spectra below 600 degrees C. With an increase in temperature, the relative content of phosphorus oxide ions, mainly [PO](+) and [P(4)O(10)](+), increased. Under further heating, we observed silver iodide and iodine dimer ions together with phosphorus dimer and tetramer ions and clusters [IPO(2)](+), [IP(2)](+), [I(3)P](+). Using the experimental logarithmic dependencies of ion signal intensities versus the reciprocal absolute temperature of the effusion cell, the apparent sublimation enthalpies Delta(s)H of the ions giving the most intense signals were estimated.

In vivo imaging of cartilage degeneration using μCT-arthrography

In vivo imaging of cartilage degeneration in small animal models is nowadays practically impossible. In the present study, we investigated the use of micro-computed tomography (microCT) in combination with a negatively charged ionic iodine dimer (ioxaglate) for in vivo assessment of cartilage degeneration in a small animal model. Cartilage degeneration was induced in the right knee of rats by injection of mono-iodoacetate (MIA). We imaged the rat knees with ioxaglate enhanced microCT-arthrography at 4, 16 and 44 days after MIA injection. Subsequently, microCT-arthrographic findings were evaluated and compared with quantitative histology of the patellar cartilage. In vivo microCT-arthrography clearly detected cartilage degeneration in the rat knee-joints, in which the ioxaglate diffused into the degenerated cartilage layer. Higher microCT-attenuation values and smaller total volumes of the cartilage layer were detected at longer time periods after MIA injection, which is quantitatively confirmed by histology. In vivo microCT-arthrography is a valuable tool for detection of minor cartilage alterations and distinguishes different stages of cartilage degeneration in a small animal model. Since microCT, at the same time, also visualizes osteophyte formation and changes in the underlying subchondral bone structures, the technique will be very useful for longitudinal overall assessment of the development of (osteo)arthritis and to study interventions in small animal models.

Structure, energy, and IR spectra of I2∙−.nH2O clusters (n=1–8): A theoretical study

The authors report theoretical results on structure, bonding, energy, and infrared spectra of iodine dimer radical anion hydrated clusters, I(2) (-).nH(2)O (n=1-8), based on a systematic study following density functional theory. Several initial guess structures are considered for each size cluster to locate minimum energy conformers with a Gaussian 6-311++G(d,p) split valence basis function (triple split valence 6-311 basis set is applied for iodine). It is observed that three different types of hydrogen bonded structures, namely, symmetrical double hydrogen bonding, single hydrogen bonding, and interwater hydrogen bonding structures, are possible in these hydrated clusters. But conformers having interwater hydrogen bonding arrangements are more stable compared to those of double or single hydrogen bonded structures. It is also noticed that up to four solvent H(2)O units can reside around the solute in interwater hydrogen bonding network. At the maximum six H(2)O units are independently linked to the dimer anion having four double hydrogen bonding and two single hydrogen bonding, suggesting the hydration number of I(2) (-) to be 6. However, conformers having H(2)O units independently linked to the iodine dimer anion are not the most stable structures. In all these hydrated clusters, the odd electron is found to be localized over two I atoms and the two atoms are bound by a three-electron hemi bond. The solvation, interaction, and vertical detachment energies are calculated for all I(2) (-).nH(2)O clusters. Energy of interaction and vertical detachment energy profiles show stepwise saturation, indicating geometrical shell closing in the hydrated clusters, but solvation energy profile fails to show such behavior. A linear correlation is observed between the calculated energy of interaction and vertical detachment energy. It is observed that formation of I(2) (-)-water cluster induces significant shifts from the normal O-H stretching modes of isolated H(2)O. However, bending mode of H(2)O remains insensitive to the successive addition of solvent H(2)O units. Weighted average energy profiles and IR spectra are reported for all the hydrated clusters based on the statistical population of individual conformers at room temperature.

Production of XeI(B) and I2(B) molecules in the plasma of a steady electric discharge in Xe/I2 mixtures

The production of excited xenon iodides and iodine dimers in the plasma of a longitudinal dc glow discharge is investigated. The discharge was ignited in iodine vapor and Xe/I2 mixtures at xenon pressures of P(Xe)=0.1–1.5 kPa and deposited powers of 10–100 W. The current-voltage characteristics of a glow discharge, the plasma emission spectra in the spectral range of 200–650 nm, and the intensities of spectral lines and molecular bands are studied as functions of the deposited power and the xenon partial pressure in a Xe/I2 mixture. It is found that the discharge plasma emits within the spectral range of 206–343 nm, which includes the 206-nm resonant line of atomic iodine and the XeI(B-X) 253-nm and I2(B-X) 343-nm molecular bands. The power deposited in the plasma and the xenon pressure P(Xe) are optimized to achieve the maximum UV emission intensity. The 7-W total UV power emitted from the entire surface of the cylindrical discharge tube is achieved with an efficiency of ≤5%.

Role of Shallow Electron Traps in the Fast Transient Optical Phenomena of Alkali Halide Crystals

We present additional evidences that the same shallow electron traps-atomic alkali impurity centres [M + ] c 0 e - are responsible for both classes (A and B) of the transient IR-absorption bands: (A) bands with maximum at 0.27-0.36 eV in NaCl, KCl, KBr, KI and RbCl (due to shallow electron traps or bound polarons) and (B) bands with maximum at 0.15-0.36 eV in NaI, NaBr, NaCl:I, KCl:I, KBr:I, RbCl:I and RbBr:I (due to on-centre STE or on-centre STE localised at iodine dimer). Both classes of the IR bands have the same location, similar shape (both exactly coincide for KCl:I and KCl at 10 or 80 K), half-width, vibration structure. It is established that the same Mollwo-Ivey plot curves E o =a/d n (d is the nn anion-cation distance, n is the exponent, a is the constant) take place for both IR band classes, if we plot instead of the IR band peak energy values the more definite values of the IR band zero-phonon line energy E 0 (for NaCl, KCl, KBr, RbCl and KCl:I) and/or the IR band low-energy edge E 0 (±0.03 eV) values (for NaBr, NaI, NaCl:I, KBr:I, RbCl:I and RbBr:I). Two types of the [M + ] c 0 e - centres are predominant: (i) [Na + ] c 0 e - in KX and RbX host crystals, for which the relation E 0 ≃6.15/d 2.74 is valid, and (ii) [Li + ] c 0 e - in NaX host crystals for which the relation E 0 ≃29.4/d 4.72 is valid. The Mollwo-Ivey relation E 0 ≃18.36/d 2.70 is valid as well for the F' band in NaCl, KCl, KBr, KI, RbCl, RbI, if we use the F' centre optical binding energy E o values. Under irradiation at 77 or 4.2 K the shallow trapped electron centres ([M + ] c 0 e - and F' centres) and their associations with the V k -type centres, i.e., dipolar pairs {[M + ] c 0 e - …V k } and {F'…V k } are created. Such a quasi-molecular electronic transients have a very wide lifetime spectrum (τ ≥ 1 ns) and can play a great role in the intense pulse excitation experiments.

Structure and dynamics of N2–IH

The ground state rotational spectra and internal dynamics in five isotopomers N214–IH, N214–ID, N215–IH, N14N15–IH, and N15N14–IH of the nitrogen–hydrogen iodine dimer have been investigated by pulsed-nozzle, Fourier-transform microwave spectroscopy. Analysis of the recorded spectra yields rotational, centrifugal distortion, nuclear quadrupole and spin-rotation coupling constants for the five isotopomers. The spectroscopic constants are interpreted in terms of a ground-state NN–IH structure using the parameters rcm, kσ, and the oscillation angles θN2 and θHI of the N2 and IH moieties. For N214–IH, the values rcm=4.197 872(67) Å, kσ=1.461 52(32) N/m, θN2=25.61(22)°, and θHI=23.454 6(91)° are obtained. The rotational transitions of N214–IH, N214–ID, and N215–IH show a doubling, which is a consequence of tunneling associated with the interchange of the two nitrogen nuclei. The experimental findings are compared with results from ab initio calculations.

Laser-induced fluorescence of molecule in an undergraduate student laboratory

An experiment on laser-induced fluorescence of the iodine dimer is reported. The experiment, meant for an advanced undergraduate physics laboratory, requires relatively simple and inexpensive apparatus yet it introduces students to essential laser spectroscopy methods. Observation of the molecular spectrum demonstrates basic principles of quantum mechanics. Molecular parameters such as bond length, force constant, anharmonicity of the interatomic potential etc may be obtained from the analysis of the data. Finer phenomena, such as intensity distribution of spectral lines or collisional energy transfer between rotational levels, can also be studied. Apparatus, specific results and various stages of data analysis are described in the paper.Streszczenie (In Polish). Przedstawiamy doswiadczenie dotyczace badania widma czasteczki przez obserwacje fluorescencji wzbudzonej swiatlem laserowym. Doswiadczenie to, przeznaczone dla pracowni dydaktycznych, zapoznaje studentów z metodami spektroskopii laserowej, mimo ze wymaga stosunkowo prostej i taniej aparatury. Obserwowane widmo czasteczkowe unaocznia podstawowe zasady mechaniki kwantowej. Analiza wyników doswiadczenia pozwala wyznaczyc takie parametry czasteczki jak dlugosc wiazania, stala silowa, anharmonicznosc potencjalu czasteczkowego itd. Mozliwa jest tez obserwacja subtelniejszych zjawisk, takich jak rozklad natezen linii widmowych lub zderzeniowy przekaz energii wzbudzenia miedzy poziomami rotacyjnymi. Artyku przedstawia uklad doswiadczalny, przykladowe wyniki pomiarów oraz kolejne etapy analizy otrzymanych rezultatów.

Infrared transient absorption and electronic state of localized self-trapped excitons in KCl:I.

The infrared transient absorption and electronic state of the on-center-type self-trapped exciton (STE) localized at an iodine dimer in KCl:I were investigated. The polarization properties and vibronic structure of the absorption band indicate that the electronic state of the on-center-type STE is rather extended so that the splitting of the 2p-like sublevels is very small.

The Transient Absorption Due to Self-Trapped Excitons Localized at Iodine Dimers in Alkali Halide Crystals

The transient absorption spectra of a self-trapped exciton (STE) localized at iodine dimers (I 2 2- * ) in iodine-doped alkali chloride and bromide crystals (AX:I; A=Na, K, Rb; X=Cl, Br) have been investigated. The absorption bands due to electron-transitions appear below 1 eV, and the bands due to hole-transitions around 1.5 and 3.0 eV. The absorption bands due to the electron-transitions are located in much lower energy region than those of intrinsic STEs in nominally pure alkali chloride or bromide crystals. The bands due to the hole-transitions are very similar to those of V k (I 2 - ) centers in alkali iodide crystals. These results suggest that the STE localized at iodine dimers is in the “on-center” configuration and its electronic state is diffused in comparison with that of “off-center” type STE.