Self-broadening in the fundamental bands of HF and HCl

Self-broadened lineshapes in the fundamental bands of HF and HCl have been measured with a high-resolution difference-frequency laser spectrometer. Self-induced broadenings, shifts, and collisional narrowings have been extracted by least-squares fitting several collisional profiles to the spectra. At low pressures, the collisional narrowing effect causes deviations of the lineshapes from the Voigt profile having a Doppler-fixed Gaussian component, and yields a measure of the diffusion constants of the molecules.     

Spectral intensities in the fundamental bands of HF and HCl

The transition intensities of the fundamental bands of natural isotopic HF and HCl vapors have been measured with Doppler-limited resolution using a tunable difference-frequency laser spectrometer. Precise values for the band intensities, vibrational moments and Herman-Wallis F factors have been obtained for H¹⁹F, H³⁵Cl and H³⁷Cl.     

Vibrational-rotational Einstein coefficients for HF/DF and HCl/DCl

The RKR potential functions have been combined with the best experimentally based dipole functions to calculate the Einstein coefficients for HF/DF and HCl/DCl. Calculations were done for the Δν = 1,2,3 transitions for a wide range of ν′ (?15 for HF/DF and ?8 for HCl/ DCl) and J′ (?25). Experimental tests involving comparison of P- and R-branch line intensities for high-J′ transitions of the HF (ν₁ → ν₀, ν₂ → ν₁ and ν₃ → ν₂ bands) and the Δν = 2 and Δν = 1 transitions for HF/DF and HCl are done to examine the reliability of the Einstein coefficients for the rotational and vibrational levels, respectively. Good agreement is obtained for HF/DF even for the high-J′ R-branch intensities which vary markedly with J′. But the data suggest improvement is needed in the dipole functions for HCl (and DCl).     

电子被HF和HCl分子散射总截面的计算

利用光学势方法计算了能量在１０ｅＶ—１０００ｅＶ范围内电子被Ｈ、Ｆ和Ｃｌ原子散射的总截面，并与已有的实验结果和理论计算进行了比较；又利用可加性规则（ａｄｄｉｔｉｖｉｔｙｒｕｌｅ）计算得到了电子被ＨＦ和ＨＣｌ分子散射的总截面，计算结果也与已有的实验结果和理论计算进行了比较     

HF分子电子基态和激发态的MRCI计算

应用舍Davidson修正的多参考组态相互作用（MRCI）方法,在aug-cc-pVTZ基组水平上对HF基态及最低的多个单重和三重电子激发态进行了势能扫描计算.结合群论原理及分子的离解极限,分析了电子态势能曲线的特征,得出激发态B¹S⁺对应的离解极限为H⁺+F^-（¹S）.基于势能曲线,数值求解核运动的径向Schrodinge方程,得到J=0时束缚电子态X¹S⁺,B¹S⁺,C¹P和D¹S⁺的振动能级和转动常数,继而进行数据拟合得到电子态的光谱常数,基态X¹S⁺:ω_e=4146.94 cm^-1,ω_ez_e=88.08 cm^-1,B_e=21.22 cm^-1,a=0.785 cm^-1;B¹S⁺态:ω_e=1131.37 cm^-1,ω_ex_e=17.28 cm^-1,B_e=3.96 cm^-1,a_e=0.0215 cm^-1,C¹P态:ω_e=2696.37 cm^-1,ω_ex_e=73.43 cm^-1,B_e=15.91 cm^-1,a_e=0.776 cm^-1,D¹S⁺态:ω_e=3104.22 cm^-1,ω_ex_e=118.92 cm^-1,B_e=17.25 cm^-1,a_e=0.992 cm^-1,拟合结果与实验值吻合的较好.     

HF分子电子基态和激发态的MRCI计算

应用含Davidson修正的多参考组态相互作用(MRCI)方法, 在aug-cc-pVTZ基组水平上对HF基态及最低的多个单重和三重电子激发态进行了势能扫描计算. 结合群论原理及分子的离解极限, 分析了电子态势能曲线的特征, 得出激发态B1对应的离解极限为H++F-(1S). 基于势能曲线, 数值求解核运动的径向Schrödinger方程, 得到J=0时束缚电子态X1, B1C1和D1的振动能级和转动常数, 继而进行数据拟合得到电子态的光谱常数, 基态X1e=4146.94 cm-1, exe =88.08 cm-1, e=21.22 cm-1, e=0.785 cm-1; B1态：e=1131.37 cm-1,exe =17.28 cm-1, e=3.96 cm-1, e=0.0215 cm-1, C1态e=2696.37 cm-1, exe =73.43 cm-1, e=15.91 cm-1, e=0.776 cm-1, D1态e=3104.22 cm-1, exe =118.92 cm-1, e=17.25cm-1, e=0.992cm-1, 拟合结果与实验值吻合的较好.     

Microscopic calculations of ferroelectric instability in perovskite crystals

First-principles calculations are performed relating to the stability of a series of perovskite crystals with respect to transition to the ferroelectric and the antiferroelectric state. The calculations employ the generalized Gordon-Kim method, in which the total charge density of an ionic crystal is represented as a superposition of the densities of the individual ions. In the spirit of the nonequilibrium thermodynamics of Leontovich the charge density of an individual ion is calculated in the presence of external auxiliary fields which deform this density. Multipole deformations up to quadrupole are taken into account. The actual magnitude of the deformation is found by minimizing the total energy of the crystal in the Thomas-Fermi-Dirac approximation. The calculated values of the ion shifts in the ferroelectric phase for BaTiO₃, and also the electron contribution to the dielectric constant ε _∞ and the dynamic Born effective charges Z ^eff are found to be in good agreement with the experimental data. The proposed method allows one to obtain an analytical expression for ε _∞, Z ^eff, and the dynamic vibration matrix. It is shown that these expressions formally coincide with the expressions arising in the phenomenological models of the polarized and deformed ion. Analysis of the expressions obtained confirms the validity of the classical theory of ferroelectrics of displacement type for perovskite crystals. Zh. éksp. Teor. Fiz. 114, 333–358 (July 1998)     

Investigation of negative ion states in HCl and HF by configuration interaction methods

Multi-reference configuration interaction calculations are employed for the study of Born-Oppenheimer potential energy curves in HF/HF^- and HCl/HCl^-. Large gaussian basis sets including negative ion functions as well as diffuse s, p and d AOs are employed thereby. In HCl^- a repulsive 2Σ⁺ state emerges from the calculations approximately 4·2 eV above the HCl X ¹Σ⁺ ground state; no such entity could be observed in HF^- in the energy range treated. All other CI roots which produce potential curves parallel to and above the X ¹Σ⁺ curve are found to possess quite diffuse charge distributions in the basis set variations undertaken and can therefore not be considered resonant states but rather as discrete representations of free-electron species in the HX + e^- continuum. For large internuclear distances the HF^- and HCl^- curves lie below those of the neutral species, whereby the crossing between the X ²Σ⁺ ionic and X ¹Σ⁺ curves are calculated to occur at 3·2 a ₀ in HCl/HCl^- and 2·6 a ₀ in HF/HF^-. Finally it is argued that non-adiabatic effects involving the low energy HX^- continuum states in the Born-Oppenheimer approximation and the bound HX^- species at large internuclear separations (with continuation inside the HX potential well) are ultimately responsible for observed electron scattering resonances, in accordance with recent work of Domcke and Cederbaum and of Nesbet.     

Line narrowing effect on the retrieval of HF and HCl vertical profiles from ground-based FTIR measurements

Collision-induced line narrowing, which has been discovered in the 1950s and investigated thoroughly in the laboratory since then, has yet never been taken into account in the spectroscopic remote sensing of the atmosphere. This work investigates the effect of collision-induced line narrowing onto the retrieval of HCl and HF vertical profiles from ground-based solar absorption FTIR measurements made at the NDSC station of the Jungfraujoch (46.5^°N, 8^°E and 3580 m above see level). The retrievals are performed with the Atmosphit software, recently developed at the Université Libre de Bruxelles. It is presented in this paper for the first time and is validated against the widely used SFIT2 software. The impact of the line narrowing onto the retrieval of HCl and HF vertical profiles is examined relying on careful information content and error budget analyses. We report that the effect is relatively weak for HCl but significant for HF. Confirmation of the need to take the line narrowing into account for the retrieval of vertical profiles from ground-based FTIR spectra is given by comparison with data from the HALOE space borne instrument, rather insensitive to this spectroscopic effect.     

Magnetic properties and molecular quadrupole moment of HF and HCl by molecular-beam electric-resonance spectroscopy

The radio-frequency spectra of HF and H³⁵Cl in an external electric and magnetic field are measured using a high-resolution molecular-beam electric-resonance spectrometer. The measurements are in the lowest vibrational state (v = 0) and the first rotational state (J = 1). The spectra are analyzed using a standard Hamiltonian. The magnetic properties of the molecules are derived using methods introduced by Ramsey. The results, corrected for the effects of molecular vibrations, are:

     

12.

Molecular dynamics calculations for HCl in a matrix of solid Ar     

Shuichi Nosé  Michael L. Klein 《Molecular physics》2013,111(5):1063-1071

We present the results of molecular dynamics calculations on HCl molecules, matrix-isolated in solid fcc argon, using the recently proposed M2 potential of Hutson and Howard. The power spectrum of the centre of mass velocity autocorrelation function of the HCl molecules is in good agreement with the experimental far infrared spectrum. Although there is considerable rotational motion of the HCl molecules, the Cl-H bond vector shows a preference for the crystallographic ?111? direction rather than the ?110? direction suggested by the dimer structure.     

13.

Theoretical investigation into dipole-moment functions of HF, HCl, and HBr molecules at small internuclear separations     

M. A. Buldakov  E. V. Koryukina  V. N. Cherepanov  Yu. N. Kalugina 《Russian Physics Journal》2006,49(11):1230-1235

Ab initio calculations of the dipole moment functions are performed within the united atom approximation in the first-order perturbation theory for the ground electronic states of HF, HCl and HBr molecules in the range of small internuclear separations. The calculation results are used for correction of the semi-empirical dipole-moment functions of these molecules obtained earlier. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 71–75, November, 2006.     

14.

First-principles calculations of the dielectric and vibrational properties of ferroelectric and paraelectric BaAl2O4     

《Physics letters. A》2014,378(26-27):1867-1870

First-principles calculations have been conducted to study the structural, dielectric, and vibrational properties of ferroelectric and paraelectric BaAl₂O₄. High-frequency and static dielectric constants, and phonon frequencies at the Brillouin zone center are reported. Both BaAl₂O₄ polymorphs are promising infrared-transparent materials due to their low electronic dielectric constants. The ferroelectric and paraelectric BaAl₂O₄ have much smaller permittivity compared to the classical ferroelectric materials. From an atomic nanostructure standpoint, the abnormally low permittivity of BaAl₂O₄ polymorphs is mainly related to low coordination numbers of Ba (9) and Al (4).     

15.

Comparative study of NH₄OH and HCl etching behaviours on AlGaN surfaces     

Rakesh Sohal  Piotr Dudek 《Applied Surface Science》2010,256(7):2210-2214

A controlled AlGaN surface preparation method avails to improve the performance of GaN-based HEMT devices. A comparative investigation of chemical treatments by (1:10) NH₄OH:H₂O and (1:10) HCl:H₂O solutions for AlGaN surface preparation by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) is reported. The XPS data clearly reveal that the native oxide on AlGaN was composed of Al₂O₃, Ga₂O₃ and NO compounds. These compounds were etched off partially or completely by both the chemical treatments, namely NH₄OH or HCl solutions, independently. The HCl treatment etches out Al₂O₃ completely from native oxide unlike NH₄OH treatment. The HCl treatment results in larger amount of carbon segregation on AlGaN surfaces, however it removes all oxides’ compounds faster than NH₄OH treatment. The AFM results reveal the improvement of surface morphology by both the chemical treatments leading to the surface roughness RMS values of 0.24 nm and 0.21 nm for NH₄OH and HCl treated AlGaN layers, respectively.     

16.

Ab Initio calculations of the lattice dynamics and the ferroelectric instability of the BiFeO3 multiferroic     

A. F. Ravinski  V. V. Triguk  I. I. Makoed 《Physics of the Solid State》2014,56(9):1799-1805

The pressure dependences of the vibration frequencies of the bismuth ferrite crystal lattice in the ferroelectric and paraelectric rhombohedral phases have been calculated from first principles in terms of the LSDA + U approximation. It has been found that there is a linear relationship between the magnetic moments of iron cations and the band gaps calculated using the same parameters of the correlation interaction. An analysis of the pressure dependences of the frequencies of the transverse optical phonons indicates their high stability in both the paraelectric and ferroelectric phases, which is not typical for classical displacive-type ferroelectrics.     

17.

An effective Hamiltonian for diatomic molecules: Ab initio calculations of parameters of HCl+     

J.M Brown  E.A Colbourn  J.K.G Watson  F.D Wayne 《Journal of Molecular Spectroscopy》1979,74(2):294-318

The form of the effective Hamiltonian for a diatomic molecule in an electronic state intermediate between Hund's cases (a) and (b) is reexamined. The derivation is performed in three stages: (i) an electronic contact transformation removes the effects of matrix elements which couple different electronic states; (ii) a vibrational contact transformation removes matrix elements coupling different vibrational states; and (iii) a spin-rotational contact transformation removes indeterminacies in the final Hamiltonian. Expressions for the effective parameters resulting from these transformations are presented. The Hamiltonian is in a convenient form for fitting to experimental data, and the formulas for the parameters assist in the comparison with ab initio calculations. The relations between the present parameters and those employed in the computer program of Zare, Schmeltekopf, Harrop, and Albritton [J. Mol. Spectrosc.46, 37–66 (1973)] are given, and make it possible to correct a previous misunderstanding regarding the value of the spin-rotation parameter γ_e in the X²Π state of HCl⁺. The parameters obtained for this state are compared with ab initio calculations which take account of first-order perturbations within the state and second-order perturbations from the A²Σ⁺ state and from the four states of the configuration … $\text{σ}{}^2\text{π}{}^2\text{σ}{}^1$. The A²Σ⁺ state is the dominant perturber, but the contributions from the other states are not negligible. For example, their contribution to γ_e is larger than the first-order contribution.     

18.

Refractive index,band gap energy,dielectric constant and polarizability calculations of ferroelectric Ethylenediaminium Tetrachlorozincate crystal     

《Journal of Physics and Chemistry of Solids》2015

Single crystal of Ethylenediaminium Tetrachlorozincate has been grown by slow evaporation method. The single crystal XRD study confirms the orthorhombic structure of the crystal. The presence of functional group vibrations are ascertained through FTIR and Raman studies. In optical studies, the insulating behaviour of the material is established by Tauc plot. The refractive index and the real dielectric constant of the crystal are calculated. The electronic polarizability in the high frequency optical region is also calculated from the dielectric constant values by using the Clausius–Mossotti equation. The large value of dielectric constant is identified through dielectric studies and it points to the ferroelectric behaviour of the material. Further an experimental study confirms the ferroelectric behaviour of the material. The total polarizability of the crystal owing to the space charge, dipole, ionic and electronic polarizability contributions is obtained experimentally, and it matches well with the theoretically obtained value from Penn analysis. Further, Plasmon energy and Fermi energy of the material are also calculated using Penn analysis.     

19.

First-principles effective Hamiltonian calculations of the electrocaloric effect in ferroelectric BaxSr1−xTiO3     

《Physics letters. A》2020,384(4):126093

     

20.

Noble-gas broadening of vibration-rotation lines belonging to diatomic molecules—II. Theoretical calculations of HCl lineshifts and widths     

C. Boulet  P. Isnard  A. Levy 《Journal of Quantitative Spectroscopy & Radiative Transfer》1973,13(9):897-909

The Anderson-Tsao-Curnutte theory is generalized to account for the vibrational dependence of line shifts and widths in the case of noble-gas-broadened HCl lines. Buckingham's intermolecular potential is used and good agreement with experimental values is obtained. Comparison is made with Herman and Tipping's semi-empirical potential. The conditions under which the theory should be applied are pointed out, especially cutoff procedures, trajectory shapes, and velocity averaging.     

	HF	H35Cl
$\text{g}{}_{\mathrm{J}}$	0.74104(15)	0.45935(9)
$\text{χ}{}_{\mathrm{|}}\text{- χ}{}_{\mathrm{\delta }}\text{(}\text{kHz/(kG)}{}^2\text{)}$	0.132(6)	?0.048(18)
$\text{(χ}{}_{\mathrm{|}}\text{- χ}{}_{\mathrm{\delta }}\text{)}{}^{\mathrm{d}}\text{(10}{}^{\mathrm{?6}}\text{erg/G}{}^2\text{·mole}\text{)}$	1.342(25)	3.49(10)
$\text{(σ}{}_{\mathrm{|}}\text{- σ}{}_{\mathrm{\delta }}\text{)}{}_{\mathrm{H}}\text{(}\text{ppm}\text{)}$	24(9)	21(5)
$\text{(σ}{}_{\mathrm{|}}\text{- σ}{}_{\mathrm{\delta }}\text{)}{}_{\mathrm{H}}{}^{\mathrm{d}}\text{(}\text{ppm}\text{)}$	?96(9)	?148(7)
$\text{(σ}{}_{\mathrm{|}}\text{- σ}{}_{\mathrm{\delta }}\text{)}{}_{\mathrm{<mtext>hal</mtext>}}\text{(}\text{ppm}\text{)}$	108(9)	300(24)
$\text{(σ}{}_{\mathrm{|}}\text{- σ}{}_{\mathrm{\delta }}\text{)}{}_{\mathrm{<mtext>hal</mtext>}}{}^{\mathrm{d}}\text{(}\text{ppm}\text{)}$	?1(9)	?4(25)
$\text{θ (10}{}^{\mathrm{?26}}\text{esu cm}{}^2\text{)}$	2.36(3)	3.74(12)

Molecular dynamics calculations for HCl in a matrix of solid Ar

We present the results of molecular dynamics calculations on HCl molecules, matrix-isolated in solid fcc argon, using the recently proposed M2 potential of Hutson and Howard. The power spectrum of the centre of mass velocity autocorrelation function of the HCl molecules is in good agreement with the experimental far infrared spectrum. Although there is considerable rotational motion of the HCl molecules, the Cl-H bond vector shows a preference for the crystallographic ?111? direction rather than the ?110? direction suggested by the dimer structure.     

Theoretical investigation into dipole-moment functions of HF, HCl, and HBr molecules at small internuclear separations

Ab initio calculations of the dipole moment functions are performed within the united atom approximation in the first-order perturbation theory for the ground electronic states of HF, HCl and HBr molecules in the range of small internuclear separations. The calculation results are used for correction of the semi-empirical dipole-moment functions of these molecules obtained earlier. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 71–75, November, 2006.     

First-principles calculations of the dielectric and vibrational properties of ferroelectric and paraelectric BaAl2O4

First-principles calculations have been conducted to study the structural, dielectric, and vibrational properties of ferroelectric and paraelectric BaAl₂O₄. High-frequency and static dielectric constants, and phonon frequencies at the Brillouin zone center are reported. Both BaAl₂O₄ polymorphs are promising infrared-transparent materials due to their low electronic dielectric constants. The ferroelectric and paraelectric BaAl₂O₄ have much smaller permittivity compared to the classical ferroelectric materials. From an atomic nanostructure standpoint, the abnormally low permittivity of BaAl₂O₄ polymorphs is mainly related to low coordination numbers of Ba (9) and Al (4).     

Comparative study of NH4OH and HCl etching behaviours on AlGaN surfaces

A controlled AlGaN surface preparation method avails to improve the performance of GaN-based HEMT devices. A comparative investigation of chemical treatments by (1:10) NH₄OH:H₂O and (1:10) HCl:H₂O solutions for AlGaN surface preparation by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) is reported. The XPS data clearly reveal that the native oxide on AlGaN was composed of Al₂O₃, Ga₂O₃ and NO compounds. These compounds were etched off partially or completely by both the chemical treatments, namely NH₄OH or HCl solutions, independently. The HCl treatment etches out Al₂O₃ completely from native oxide unlike NH₄OH treatment. The HCl treatment results in larger amount of carbon segregation on AlGaN surfaces, however it removes all oxides’ compounds faster than NH₄OH treatment. The AFM results reveal the improvement of surface morphology by both the chemical treatments leading to the surface roughness RMS values of 0.24 nm and 0.21 nm for NH₄OH and HCl treated AlGaN layers, respectively.     

Ab Initio calculations of the lattice dynamics and the ferroelectric instability of the BiFeO3 multiferroic

The pressure dependences of the vibration frequencies of the bismuth ferrite crystal lattice in the ferroelectric and paraelectric rhombohedral phases have been calculated from first principles in terms of the LSDA + U approximation. It has been found that there is a linear relationship between the magnetic moments of iron cations and the band gaps calculated using the same parameters of the correlation interaction. An analysis of the pressure dependences of the frequencies of the transverse optical phonons indicates their high stability in both the paraelectric and ferroelectric phases, which is not typical for classical displacive-type ferroelectrics.     

An effective Hamiltonian for diatomic molecules: Ab initio calculations of parameters of HCl+

The form of the effective Hamiltonian for a diatomic molecule in an electronic state intermediate between Hund's cases (a) and (b) is reexamined. The derivation is performed in three stages: (i) an electronic contact transformation removes the effects of matrix elements which couple different electronic states; (ii) a vibrational contact transformation removes matrix elements coupling different vibrational states; and (iii) a spin-rotational contact transformation removes indeterminacies in the final Hamiltonian. Expressions for the effective parameters resulting from these transformations are presented. The Hamiltonian is in a convenient form for fitting to experimental data, and the formulas for the parameters assist in the comparison with ab initio calculations. The relations between the present parameters and those employed in the computer program of Zare, Schmeltekopf, Harrop, and Albritton [J. Mol. Spectrosc.46, 37–66 (1973)] are given, and make it possible to correct a previous misunderstanding regarding the value of the spin-rotation parameter γ_e in the X²Π state of HCl⁺. The parameters obtained for this state are compared with ab initio calculations which take account of first-order perturbations within the state and second-order perturbations from the A²Σ⁺ state and from the four states of the configuration … $\text{σ}{}^2\text{π}{}^2\text{σ}{}^1$. The A²Σ⁺ state is the dominant perturber, but the contributions from the other states are not negligible. For example, their contribution to γ_e is larger than the first-order contribution.     

Refractive index,band gap energy,dielectric constant and polarizability calculations of ferroelectric Ethylenediaminium Tetrachlorozincate crystal

Single crystal of Ethylenediaminium Tetrachlorozincate has been grown by slow evaporation method. The single crystal XRD study confirms the orthorhombic structure of the crystal. The presence of functional group vibrations are ascertained through FTIR and Raman studies. In optical studies, the insulating behaviour of the material is established by Tauc plot. The refractive index and the real dielectric constant of the crystal are calculated. The electronic polarizability in the high frequency optical region is also calculated from the dielectric constant values by using the Clausius–Mossotti equation. The large value of dielectric constant is identified through dielectric studies and it points to the ferroelectric behaviour of the material. Further an experimental study confirms the ferroelectric behaviour of the material. The total polarizability of the crystal owing to the space charge, dipole, ionic and electronic polarizability contributions is obtained experimentally, and it matches well with the theoretically obtained value from Penn analysis. Further, Plasmon energy and Fermi energy of the material are also calculated using Penn analysis.     

Noble-gas broadening of vibration-rotation lines belonging to diatomic molecules—II. Theoretical calculations of HCl lineshifts and widths

The Anderson-Tsao-Curnutte theory is generalized to account for the vibrational dependence of line shifts and widths in the case of noble-gas-broadened HCl lines. Buckingham's intermolecular potential is used and good agreement with experimental values is obtained. Comparison is made with Herman and Tipping's semi-empirical potential. The conditions under which the theory should be applied are pointed out, especially cutoff procedures, trajectory shapes, and velocity averaging.