Theoretical study of low lying electronic states of GdO

Low lying electronic states of GdO have been investigated by complete active space SCF (CASSCF) and multireference singly and doubly excited configuration interaction (MRSDCI) calculations using the model core potential (MCP) method. The 4f electrons of Gd were included explicitly in the valence space. Relativistic effects were incorporated in the MCP and basis sets for Gd at the level of Cowan and Griffin's quasirelativistic Hartree—Fock method. The ⁹Σ^? state (f⁷σ) was the ground state, and excited states, ⁹Δ, ⁹Π, 2⁹Σ^?, ⁷Σ^?, ⁷Δ, ⁷Π, and 2⁷E^?, lay between 0 ～ 22 300 cm^?1. The energy separations for these states agreed well with available experimental values. Calculated GdO bond lengths and vibrational frequencies for these states are in the ranges of 1.81–1.85 Å and of 800–880 cm^?1, respectively. Mulliken population analysis showed that the gross population of the 4f orbitals was 7.1 e for all these states, and that the 4f electrons were strongly localized on Gd atom. The effective charge distribution was approximated to be Gd⁺O^?. The σ and π bonding orbitals were mainly formed by Gd 5d and O 2p orbitals.     

The structure and vibrational features of proton disolvates in water–ethanol solutions of HCl: the combined spectroscopic and theoretical study

The infrared (IR) spectra of water–ethanol (EtOH) solutions of HCl are measured over a wide range of acid concentration at fixed H₂O―EtOH ratios (1 : 1, 1 : 2, and 1 : 40). In these systems, different proton disolvates with (quasi)symmetrical H‐bonds are formed. Their structure and vibrational features are revealed by the density functional theory method coupled with the polarizable continuum model of solvation. In dilute acidic solutions, the Zundel‐type H₅O₂⁺ ion is mainly formed. In concentrated HCl solutions, the ions (H₂O···H···O(H)Et)⁺ and (Et(H)O···H···O(H)Et)⁺ with the quasi‐symmetrical O···H⁺···O unit having O···O separation <2.45 Å appear. The first ion characterized by the IR‐intensive band around 1800 cm^?1 is mainly formed in the 1 : 1 water–ethanol systems. The second ion exists in the 1 : 2 and 1 : 40 water–ethanol systems. Its spectroscopic signatures are the groups of the IR‐intensive bands around 800 and 1050 cm^?1. In highly concentrated HCl solutions with the 1 : 40 water–ethanol ratio, a neutral Et(H)O···H⁺···Cl^? complex exists. Copyright © 2013 John Wiley & Sons, Ltd.     

Spectroscopic,structural and theoretical studies of 2‐methyl‐4‐nitroaniline (MNA) crystal. Electronic transitions in IR

Polarized FT‐IR, Raman, neutron scattering (IINS), and UV‐Vis‐NIR spectra of 2‐methyl‐4‐nitroaniline (MNA) crystal plates, powder, and solutions were measured in the 10–50 000 cm⁻¹ range. The FT‐IR spectrum of deuterated MNA (DMNA) in KBr pellet, the Raman spectrum of the DMNA powder as well as the EPR spectrum of the MNA powder were also recorded. Complete assignments of bands to normal vibrations have been proposed. Density functional theory (DFT) calculations of wavenumbers and potential energy distribution (PED) have been performed to strengthen the assignments. The analysis of vibrational and electronic spectra has revealed vibronic couplings in MNA molecules in solutions and in crystals. In the polarized FT‐IR spectra of the crystal five unusually large bands are observed in MIR and NIR regions. Their origin is discussed in terms of N H···O, C H···O, C H···H N hydrogen bonds, intermolecular charge transfers, electrostatic interactions, and ion radicals formation in the crystal. The role of a methyl group introduction to 4‐nitroaniline is analyzed. The crystal structure of MNA at the room temperature was re‐investigated. Copyright © 2008 John Wiley & Sons, Ltd.     

Experimental and theoretical FT‐IR and FT‐Raman spectroscopic analysis of N1‐methyl‐2‐chloroaniline

In this work, the experimental and theoretical vibrational spectra of N1‐methyl‐2‐chloroaniline (C₇H₈NCl) were studied. FT‐IR and FT‐Raman spectra of the title molecule in the liquid phase were recorded in the region 4000–400 cm^?1 and 3500–50 cm^?1, respectively. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method (B3LYP) with the 6‐311++G(d,p) basis set. The vibrational frequencies were calculated and scaled values were compared with experimental FT‐IR and FT‐Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. ¹³C and ¹H NMR chemical shifts results were compared with the experimental values. The optimized geometric parameters (bond lengths and bond angles) were given and are in agreement with the corresponding experimental values of aniline and p‐methyl aniline. Copyright © 2008 John Wiley & Sons, Ltd.     

Electric field dissociation of H+ 2: close-coupled scattering calculations

Close-coupling scattering calculations have been carried out to predict the magnitude of electric fields required to dissociate specific vibration—rotation levels in H⁺ ₂. Results for electric fields up to 40 kV cm^?1, which may dissociate levels up to 25 cm^?1 below the dissociation limit, are presented. The results are used to simulate spectra which are compared with experimental spectra. A method for extracting the eigenphase sum from a coupled channel scattering calculation is described in the appendix and used in the calculations.     

A vibrational spectroscopic investigation of rhodanine and its derivatives in the solid state

Raman and infrared spectra are reported for rhodanine, 3‐aminorhodanine and 3‐methylrhodanine in the solid state. Comparisons of the spectra of non‐deuterated/deuterated species facilitate discrimination of the bands associated with N H, NH₂, CH₂ and CH₃ vibrations. DFT calculations of structures and vibrational spectra of isolated gas‐phase molecules, at the B3‐LYP/cc‐pVTZ and B3‐PW91/cc‐pVTZ level, enable normal coordinate analyses in terms of potential energy distributions for each vibrational normal mode. The cis amide I mode of rhodanine is associated with bands at ∼1713 and 1779 cm⁻¹, whereas a Raman and IR band at ∼1457 cm⁻¹ is assigned to the amide II mode. The thioamide II and III modes of rhodanine, 3‐aminorhodanine and 3‐methylrhodanine are observed at 1176 and 1066/1078; 1158 and 1044; 1107 and 984 cm⁻¹ in the Raman and at 1187 and 1083; 1179 and 1074; 1116 and 983 cm⁻¹ in the IR spectra, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Molecular structure and IR spectra of bromomethanes by DFT and post-Hartree-Fock MP2 and CCSD(T) calculations

The molecular parameters (geometries, rotational constants, dipole moments) and vibrational IR spectra (harmonic wavenumbers, absolute intensities) of bromomethanes (CH₃Br, CH₂Br₂, CHBr₃, CBr₄) are predicted by a density functional theory with the hybrid Becke3-LYP functional (DFT) and post-Hartree-Fock methods (MP2, CCSD(T)) using a 6-311G(2d,2p)-type basis set. The MP2 calculations are carried out with different numbers of frozen core orbitals to find how the number of bromine orbitals used for electron correlation influences the predicted molecular parameters and IR spectra of the species in question. Three options were used: (a) all electrons (full), with both the core and valence orbitals considered; (b) partial frozen core option (pfc), when the orbitals up to 3p of bromine were frozen; and (c) full frozen core option (ffc), when all core orbitals up to 3d were frozen. The CCSD(T) calculations for geometric parameters were carried out with both the pfc and ffc options, while for the prediction of the IR spectra only the ffc option was used. In addition, the calculations at the DFT and MP2(pfc) levels with inclusion of f functions on carbon and bromine atoms in bromomethanes (and also the CCSD(T)(pfc) calculations for CH₃Br) were carried out to predict the changes in the geometric parameters and/or vibrational IR spectra of the molecules upon inclusion of f functions The geometries of bromomethanes (particularly the CBr bond lengths) are predicted better by the DFT and CCSD(T) calculations when the f functions (in particular on bromine atom) are included, while the MP2 calculations without f functions are good enough for correct predictions of the molecular geometries. The molecular parameters and vibrational IR spectra of bromomethanes in question and their deuterated species predicted by the DFT, MP2(ffc) and CCSD(T)(ffc) with the 6-311G(2d,2p) basis set agree well with the available experimental data.     

Molecular structure,vibrational spectroscopic,first‐order hyperpolarizability and HOMO,LUMO studies of 3‐hydroxy‐2‐naphthoic acid hydrazide

The Fourier‐transform infrared spectrum of 3‐hydroxy‐2‐naphthoic acid hydrazide (3H2NAH) was recorded in the region 4000–400 cm⁻¹. The Fourier‐transform Raman spectrum of 3H2NAH was also recorded in the region 3500–10 cm⁻¹. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 3H2NAH were carried out by density functional theory (DFT/B3LYP) method with 6‐31G(d,p) as basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The values of the electric dipole moment (µ) and the first‐order hyperpolarizability (β) of the investigated molecule were computed using ab initio quantum mechanical calculations. The UV spectrum was measured in ethanol solution. The calculation results also show that the 3H2NAH molecule might have microscopic nonlinear optical (NLO) behavior with non‐zero values. A detailed interpretation of the infrared and Raman spectra of 3H2NAH is also reported based on total energy distribution (TED). The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT‐IR and FT‐Raman spectra for the title molecule have also been constructed. Copyright © 2009 John Wiley & Sons, Ltd.     

The infrared spectrum of OH-compensated defect sites in C-doped MgO and CaO single crystals

The IR spectra of OH-compensated point defects in MgO (and CaO) single crystals of various purity grades were reinvestigated. Three distinct groups of IR bands appear in the O-H stretching region: A, B and C around 3550 cm^?1 (3650 cm^?1), 3300 cm^?1 (3450 cm^?1) and 3700cm^?1 (3750cm^?1). They are assigned as follows: band A to the fully compensated, band B to the half compensated and band C to the overcompensated cation vacancies, [O?V”_catH?]^×, [O?V”_cat], and [O?O?V”_catH?$\text{]}\text{?}$, respectively.Upon cooling to 80 K the band A shows a complex behavior partly due to the formation of Ha molecules by charge transfer and concommittant O^? formation: [? (H₂)”_cat?]^×. The O^? represent defect electrons or positive holes in the O^2? matrix.Bands A and B show a characteristic multiplet splitting which is caused by local lattice strains coming from carbon atoms on near-by interstitial position. The intensity ratios between the multiplet components remain constant regardless of temperature pretreatments up to 1470 K, but strong variations of the integral intensities are observed. These are caused by the highly mobile C atoms entering and leaving reversibly the cation vacancy sites as a function of temperature and of the quenching speed. When the C atoms push the H₂ molecules onto interstitial sites, an H-H stretching signal appears around 4150cm^?1.     

Low-frequency librational vibrations,boson peak,and interchain interactions in a vitreous polymer

The IR and Raman spectra of plasticized poly(methyl methacrylate) (PMMA) are measured and analyzed in the frequency range 10–120 cm^?1, in which the absorption and scattering due to the individual (85–90 cm^?1) and correlated librational vibrations (15–20 cm^?1, boson peak) preceding the appearance of relaxation dynamics manifest themselves. It is demonstrated that the presence of the boson peak as an indication of the solid-state behavior of the polymer material in the low-frequency spectra is associated with the correlation of librational vibrations not only inside macromolecules (in segments corresponding in length to the Kuhn segment) but also in segments of neighboring chains.     

Structural Characterization of RF‐Sputtered a‐C:N Thin Films by Raman,IR, and X‐ray Reflectometry Spectroscopies

Abstract

Amorphous carbon nitride thin films (a‐C:N) were deposited from a carbon target, at room temperature onto silicon substrates, by reactive RF sputtering in a gas mixture of argon and nitrogen. The structural properties of these films have been studied by Raman, infrared (IR), and X‐ray reflectometry spectroscopies. Both the IR and Raman spectra of the a‐C:N films reveal the presence of C–C, C?C, C?N, and C≡N bonding types. The Raman spectra analysis shows, an increase of the C≡N triple bonds content when the concentration of nitrogen C(N₂) in the gas mixture is increased. The Raman intensities ratio between the disorder (D) and graphitic (G) bands increases with C(N₂) suggesting an increased disorder with the incorporation of nitrogen in the carbon matrix. The effect of C(N₂) on the density of a‐C:N films was also investigated by X‐ray reflectometry measurement. The increase of the nitrogen concentration C(N₂) was found to have a significant effect on the density of the films: as C(N₂) increases from 0 to 100%, the density of the a‐C:N films decreases slightly from 1.81 to 1.62 g/cm³. The low values of density of the a‐C:N films were related (i) to the absence of C–N single bonds, (ii) to the increase of disorder introduced by the incorporation of nitrogen in the carbon matrix, and (iii) to the presence of the bands around 2350 cm^?1 and 3400 cm^?1 associated with the C–O bond stretching modes and the O–H vibration, respectively, suggesting a high atmospheric contamination by oxygen and water. The presence of these bands suggests the porous character of the studied samples.     

Solvation of AgTFSI in 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid investigated by vibrational spectroscopy and DFT calculations

In this paper we investigate the solvation of silver bis(trifluoromethylsulfonyl)imide salt (AgTFSI) in 1‐ethyl‐3‐methylimidazolium TFSI [EMI][TFSI] ionic liquid by combining Raman and infrared (IR) spectroscopies with density functional theory (DFT) calculations. The IR and Raman spectra were measured in the 200–4000 cm⁻¹ spectral region for AgTFSI/[EMI][TFSI] solutions with different concentrations ([AgTFSI] <0.2 mole fraction). The analysis of the spectra shows that the spectral features observed by dissolution of AgTFSI in [EMI][TFSI] solution originate from interactions between the Ag⁺ cation and the first neighboring TFSI anions to form relatively stable Ag complexes. The ‘gas phase’ interaction energy of a type [Ag(TFSI)₃]²⁻ complex was evaluated by DFT calculations and compared with other interionic interaction energy contributions. The predicted spectral signatures because of the [Ag(TFSI)₃]²⁻ complex were assessed in order to interpret the main IR and Raman spectral features observed. The formation of such complexes leads to the appearance of new interaction‐induced bands situated at 753 cm⁻¹ in Raman and at 1015 and 1371 cm⁻¹ in IR, respectively. These specific spectral signatures are associated with the ‘breathing’ mode and the S–N–S and S–O stretching modes of the TFSI anions engaged in the complex. Finally, all these findings are discussed in terms of interaction mechanisms enabling the electrodeposition characteristics of silver from AgTFSI/[EMI][TFSI] IL‐based electrolytic solutions. Copyright © 2015 John Wiley & Sons, Ltd.     

The He(I) photoelectron spectroscopy of heavy group IV—VI diatomics

The He(I) photoelectron spectra of the Group IV—VI diatomics GeO, GeS, GeSe, GeTe, SnS, SnSe, and SnTe are presented. The outermost valence structure of these molecules is similar to that observed in the lighter series CO, CS, etc. of this valence isoelectronic group; in each case a relatively sharp peak is assigned to ionization from the nominally non-bonding 3σ orbital and a broader band to ionization from the bonding 1π orbital. At higher binding energies the spectra exhibit several peaks where only a single peak is expected, from the (2σ)^?1 hole state. This structure is assigned to correlation peaks resulting from configuration interaction among hole states of ²Σ⁺ (Ω = $\text{1}\text{2}$) symmetry. Semi-empirical CNDO—MO calculations have been performed for these molecules, and the results are used to interpret the observed trends. In addition, a simple molecular orbital model is employed to estimate the importance of spin—orbit coupling in the valence electronic structure of the heavy IV—VI ions.     

Vibrational spectroscopic studies of the structure of di‐amino acid peptides. Part II: cyclo(L‐Asp‐L‐Asp) in the solid state and in aqueous solution

Solid‐state protonated and N,O‐deuterated Fourier transform infrared (IR) and Raman scattering spectra together with the protonated and deuterated Raman spectra in aqueous solution of the cyclic di‐amino acid peptide cyclo(L ‐Asp‐L ‐Asp) are reported. Vibrational band assignments have been made on the basis of comparisons with previously cited literature values for diketopiperazine (DKP) derivatives and normal coordinate analyses for both the protonated and deuterated species based upon DFT calculations at the B3‐LYP/cc‐pVDZ level of the isolated molecule in the gas phase. The calculated minimum energy structure for cyclo(L ‐Asp‐L ‐Asp), assuming C₂ symmetry, predicts a boat conformation for the DKP ring with both the two L ‐aspartyl side chains being folded slightly above the ring. The CO stretching vibrations have been assigned for the side‐chain carboxylic acid group (e.g. at 1693 and 1670 cm⁻¹ in the Raman spectrum) and the cis amide I bands (e.g. at 1660 cm⁻¹ in the Raman spectrum). The presence of two bands for the carboxylic acid CO stretching modes in the solid‐state Raman spectrum can be accounted for by factor group splitting of the two nonequivalent molecules in a crystallographic unit cell. The cis amide II band is observed at 1489 cm⁻¹ in the solid‐state Raman spectrum, which is in agreement with results for cyclic di‐amino acid peptide molecules examined previously in the solid state, where the DKP ring adopts a boat conformation. Additionally, it also appears that as the molecular mass of the substituent on the C^α atom is increased, the amide II band wavenumber decreases to below 1500 cm⁻¹; this may be a consequence of increased strain on the DKP ring. The cis amide II Raman band is characterized by its relatively small deuterium shift (29 cm⁻¹), which indicates that this band has a smaller N H bending contribution than the trans amide II vibrational band observed for linear peptides. Copyright © 2009 John Wiley & Sons, Ltd.     

Ab Initio Study on Structures and Vibrational Spectra of M+(H2O)Ar2 (M = Cu,Au)

Previous investigations have shown that it is difficult to acquire the infrared (IR) spectra of M⁺(H₂O) (M?=?Cu, Au) using a single IR photon by attaching an Ar atom to M⁺(H₂O). To explore whether the IR spectra can be obtained using the two Ar atoms tagging method, the geometrical structures, IR spectra and interaction energies are investigated in detail by ab initio electronic structure calculations for M⁺(H₂O)Ar₂ (M?=?Cu, Au) complexes. Two conceivable isomeric structures are found, which result from different binding sites for two Ar atoms. CCSD(T) calculations predict that two Ar atoms are most likely to attach to Cu⁺ for the Cu⁺(H₂O)Ar₂ complex, while the Au⁺(H₂O)Ar₂ complex prefers the isomer in which one Ar atom attaches to an H atom of the H₂O molecule and the other one is bound to Au⁺. Moreover, the calculated binding energies of the second Ar atom are smaller than the IR photon energy, and so it is possible to obtain the IR spectra for both Cu and Au species. The changes in the spectra caused by the attachment of Ar atoms to M⁺(H₂O) are discussed.     

共掺杂金红石TiO2的电子结构和红外光谱研究

本文对大别山双河、碧溪岭地区硬玉石英岩中的金红石进行了Fourier变换红外光谱(FTIR)分析, 结果显示所有金红石颗粒分别在3280 cm^-1和3295 cm^-1 出现强的吸收峰. 基于前人提出H在金红石结构中以孔道中心(CC)和八面体共边(BOE)方式存在的两种模型, 本文采用第一性原理计算方法研究了掺杂(Al, H)和(Fe, H)时金红石相TiO₂的晶体结构和电子结构. 根据O—H键的振动频率和O—H…O键中O—O之间距离的经验关 关键词： 2')" href="#">金红石相TiO₂ 孔道中心 电子结构 第一性原理     

二乙酰分子内价轨道4ag+4bu的电子动量谱学研究

在高分辨率(ΔE=115eV, Δp≈01a.u.)电子动量谱仪上获得了二乙酰分子(d iacetyl)最内价轨道4ag_g+4bu_u的电离能谱和动量谱的实验结果， 并用Hartree-Fock和密度泛函理论方法做了理论计算.实验结果与理论计算符合较好. 关键词： 二乙酰 内价轨道 电离能 电子动量谱     

Electrochemical Synthesis and Structure of Poly(2‐methyl‐1‐naphthylamine) Films

A novel polymer, poly(2‐methyl‐1‐naphthylamine), which was synthesized electrochemically at various temperatures from a solution containing 2‐methyl‐1‐naphthylamine, acetic acid and sodium acetate, was characterized by IR spectroscopy. The structural conclusions were based on comparisons of polymer spectra with the IR‐spectrum of the monomer, 2‐methyl‐1‐naphthylamine. IR spectroscopy indicates that the electropolymerization proceeds via the –NH₂ groups and that the poly(2‐methyl‐1‐naphthylamine) structure consists of imine (–N?C) and amine (–NH–C) links between naphthalene rings as well as a free methyl groups in the chains. An analysis of the “substitution pattern” region in the polymer's spectra suggests that the polymer molecules were formed via mixed N–C(4), N–C(5) and N–C(7) linkages between repeated units. The ratio of between the 1645 and 1620 cm^? 1 peak areas decreases with increased temperature during synthesis, indicating that 25°C is the best temperature to obtain higher molecular weights.     

A Raman spectroscopic study of the uranyl carbonate rutherfordine

The molecular structure of the uranyl mineral rutherfordine has been investigated by the measurement of its Raman spectra at 298 and 77 K and complemented with infrared spectra. The infrared spectra of the (CO₃)²⁻ units in the anti‐symmetric stretching region show complexity with three sets of carbonate bands observed. This, combined with the observation of multiple bands in the (CO₃)²⁻ bending region in both Raman and IR spectra, suggests that both monodentate and bidentate (CO₃)²⁻ units are present in the structure in accordance with the X‐ray crystallographic studies. Complexity is also observed in the IR spectra of (UO₂)²⁺ anti‐symmetric stretching region and is attributed to non‐identical UO bonds. Both Raman and infrared spectra of the rutherfordine show the presence of both water and hydroxyl units in the structure, as evidenced by IR bands at 3562 and 3465 cm⁻¹ (OH) and 3343, 3185 and 2980 cm⁻¹ (H₂O). Raman spectra show the presence of four sharp bands at 3511, 3460, 3329 and 3151 cm⁻¹. Copyright © 2007 John Wiley & Sons, Ltd.     

Fourier‐transform infrared and Raman spectra,vibrational assignment and density functional theory calculations of 1,4,5‐triazanaphthalene

The Fourier‐transform infrared (FT‐IR) (4000–50 cm⁻¹) and Raman spectra (3500–100 cm⁻¹) of 1,4,5‐triazanaphthalene in polycrystalline state were measured. Comparison between the spectra by two techniques, a series of density functional theory (DFT) calculations and the spectral behaviour upon deuteration were used for the assignment of the vibrational spectra of the title compound. The calculated vibrational wavenumbers by the B3LYP density functionals are generally consistent with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd.