Spectra Of HF Research Articles

Mixing and memory effects on the far-infrared spectra of HF in liquid SF 6.

The present work is devoted to evaluate the importance of memory and mixing effects on the far-infrarerd spectrum of HF in liquid SF 6 at two different temperatures: 228 K and 273 K. The influence of these effects in the shape of the individual rotational lines forming the spectrum is analyzed. From a quantitative point of view, mixing effects are much greater than memory ones, but qualitatively the influence of both effects is similar, consisting in an enhancement of the absorption in the low frequency side of the spectrum and a reduction in the high frequency side. Moreover, mixing effects are the principal responsible for the observed asymmetry in the rotational lines making up the spectrum.

Memory and nonadditivity effects on the far-infrared spectra of DCl, HCl and HF in liquid SF 6

The far-infrared of DCl, HCl and HF in liquid SF 6 ( T=273 K) are studied by applying a previously reported non-Markovian line-by-line spectral theory in which memory and mixing effects are explicitly considered. We analyze the importance of both effects in terms of the rotational constant of the diatomic molecule. Moreover, the influence of mixing effects on the observed resolved rotational structure is discussed.

Photochemistry of water-fluorine complexes in solid argon: infrared spectra of HF--HOF, HO--HF, and FO--HF complexes

Codeposition of H 2 O and F 2 in excess argon on a cold window at 12±1 K gave new absorptions for the Lewis acid-base H 2 O--F 2 complex. Photolysis of this sample with 220-1000-nm light formed several new products. Ab initio calculations using HONDO 7.0 and the DZP basis set were performed to support the identification of new F 2 +H 2 O product complexes. HF--HOF, FH--FOH, and FH--OHF exhibited v s (HF) modes at 3877.9, 3781.3, and 3638.0 cm -1 , respectively

The infrared emission spectra of LiF and HF

The high resolution infrared spectrum of LiF has been measured in emission with the McMath Fourier transform interferometer at Kitt Peak. A total of 800 lines with ν = 1 → 0 to ν = 8 → 7 of the main isotopomer, 7LiF, and 250 lines with ν = 1 → 0 to ν = 3 → 2 of the minor isotopomer, 6LiF, were observed. These ro-vibrational transitions and the pure rotational transitions from the literature were fit to a set of Dunham coefficients Yij and a set of mass-reduced Dunham coefficients Uij. The same spectrum shows 13 pure rotational emission transitions of HF in the vibrational ground state with J = 13 → 12 to J = 25 → 24. These transitions were used to determine an improved set of rotational constants for HF. Key words: infrared spectra, LiF, HF.

“Clathrates” (?) of noble-gas fluorides

Reactions between gold pentafluoride and alkali-earth metals fluorides in non-aqueous hydrogen fluoride were investigated. Ca(AuF 6) 2, Sr(AuF 6) 2 and Ba(AuF 6) 2 were identified. The Raman spectra of the received compounds were examined in crystalline form and in the non-aqueous HF solution. It was found out, that bis-hexafluoroaurates had high solubility in non-aqueous HF. The Raman spectra of liquid system HFM II(AuF 6)KrF 2 were investigated. The compounds of variable composition on KrF 2, where n=1+4 (Ba, Sr) and n=1+3 (Ca) were crystallized from this system, if the solvent were evaporated slowly. ▪ The results of Raman spectra analyses of obtained compounds are presented. Interaction between KrF 2 and M II(AuF 6) 2 leads to essential increase of vibrational frequency of KrF bond (up to 35 cm −1) comparing with KrF 2 (462 cm −1) and to the splitting of vibrational bond. This interaction decreases with increase of n; the possible nature of interaction is discussed. The received compounds are characterized by higher thermal stability of the “bonded” KrF 2. If heated up to 350 K KrF 2 may be quantatively obtained from the salts. If heated quickly up to 370+380 K the salts decomposes with explosion. The energy aspect of the complex salts formation is discussed. The results of interaction between M II(AuF 6) 2 and xenon fluorides will be also presented.

Microwave spectrum and electric dipole moment of NeHF

Rotational spectra of 20NeHF and 22NeHF have been measured using a pulsed-nozzle Fourier-transform microwave spectrometer. The J = 2-1 and 1-0 transitions were observed, yielding B 0 = 4514.0949(15) MHz, D J = 0.59889(19) MHz, and μ = 0.3882(21) D for 20NeHF and B 0 = 4318.53739(93) MHz, D J = 0.54021(12) MHz, and μ = 0.3917(13) D for 22NeHF. The measured dipole moments provide an estimate of 〈 P 1(cos θ)〉 = 0.21 which can be related to the anisotropy of the NeHF intermolecular potential.

Microwave and infrared electric-resonance optothermal spectroscopy of HF–HCl and HCl–HF

Microwave and infrared spectra of HF–HCl and HCl–HF have been obtained using a molecular-beam electric-resonance optothermal spectrometer, which operates by quadrupole-field focusing of polar molecules onto a bolometer detector. The HF–HCl microwave measurements extend to Ka=1, the previous Ka=0 results of Janda, Steed, Novick, and Klemperer, allowing the determination of the Ka dependence and asymmetry of the Cl quadrupole coupling constant. For the metastable HCl–HF isomer no previous spectroscopic measurements have been reported. Here, microwave spectra are observed for the Ka=0 and 1 states and interpreted in terms of an L-shaped hydrogen-bonded structure for the complex, with a 3.235 Å center-of-mass separation between the HF and HCl subunits. The DJ distortion constant indicates that the harmonic stretching force constant for HCl–HF is ∼35% larger than that of HF–HCl. Infrared spectra of the Ka=0–0 and 1–0 subbands of the H–F stretching band for HF–HCl and of the Ka=0–0 subband of the H–F stretch for HCl–HF are also reported. The vibrational predissociation linewidths depend on vibration, Ka state, isotopic species, and isomer excited.

Tunneling and shape resonance phenomena in the UV photoelectron spectra of HF and DF

The band shapes of the transitions HF + ( 2Σ +) ← HF ( 1Σ +) and DF + ( 2Σ +) ← DF ( 1Σ +) in UV photoelectron spectroscopy show both discrete and continuous character. A band shape simulation is presented using accurate potential energy curves computed with the Hartree-Fock method employing extensive configuration interaction and including a detailed rotational analysis. From the excellent agreement between observed and calculated band shapes, spectral features can be assigned as remarkable illustrations of tunneling and shape resonance phenomena.

Laser magnetic resonance rotational spectroscopy of the hydrogen halide molecular ions: H 35Cl + and H 37Cl +

Pure rotational spectra of the X 2Π vibronic ground states of H 35Cl + and H 37Cl + molecular ions have been measured by far-infrared laser magnetic resonance (LMR). The spectrometer, which contains an intracavity transverse dc discharge, is described in some detail. The theoretical formalism used to analyze the LMR spectra of HF +, HCl +, and HBr + is presented. The constants B, q, h, b, eQq 0, eQq 2, g 1, and g R were determined from a least-squares regression analysis of the J = 7 2 ← 5 2 and J = 9 2 ← 7 2 transitions in H 35Cl + and H 37Cl +. Values obtained for the molecular parameters support a model of HCl + with the electron density strongly localized on chlorine and with hydrogen exhibiting a substantial positive charge.

The eigenvalue-independent partitioning technique in Fock space: An alternative route to open-shell coupled-cluster theory for incomplete model spaces

Our recent open-shell coupled-cluster (CC) theory for incomplete model spaces, having valence holes and valence particles, is cast in an alternative form having computational advantages. An eigenvalue-independent partitioning technique in Fock space converts the CC equations for each m-hole, n-particle model space of dimension N (m,n) to a non-Hermitian eigenproblem of larger dimension, whose N (m,n) roots are the energies of interest. This alternative strategy works even in the presence of intruders, as is demonstrated by applying it to the main and satellite peaks of the IP and Auger spectra of HF and to the excitation energies of N 2.

Non-markovian far-infrared spectra of HF in liquid SF6

Non-markovian far-infrared spectra calculations for dilute solutions of HF in liquid SF6 at two different temperatures are presented in the range 0 to 250 cm-1. The fine rotational structure appearing in these spectra is discussed as function of the parameters involved in the theoretical absorption coefficient. A comparison with the spectra of other diatomic polar molecules (HCl, DCl) is also reported.

Equilibrium structures and vibrational frequencies for diatomic molecules. An assessment of the CCSDT-1 method, incorporating coupled-cluster single, double, and linearized triple excitations

The coupled-cluster single, double, and linearized triple excitation (CCSDT-1) model has been used to predict the infrared spectra of HF, N 2, CO, and OH −. Double zeta plus polarization (DZ + P) and triple zeta plus double polarization (TZ + 2P) basis sets were used. Comparisons with experiment and with configuration interaction (CI) methods are made.

Tunneling and shape resonance phenomena in the UV photoelectron spectra of HF and DF

The UV photoelectron spectroscopic band shape of the transitions HF +( 2Σ +)←HF( 1Σ +) and DF +( 2Σ +)←DF( 1Σ +) shows both discrete and continuous structure. Previously observed features are shown to be a remarkable illustration of tunneling and shape resonance phenomena.

Étude des mélanges eau–HF par spectroscopie infrarouge à transformée de Fourier

An analysis of the ir spectra of HF–H2O mixtures containing from 10 to 97% of HF has been used to determine the evolution of the ionic species of HF. The results indicate that water and the ions H3O+F−, H3O+, and F− are present in the solutions containing less than 46% w/w of HF. In the solutions containing at least 50% w/w of HF, bands characteristic of the ion HF2− start appearing and their intensity increases with the concentration of HF, up to a concentration of 90%. As well, polymers of (HF)n have been detected in the solutions containing the highest concentration of HF. These results can be used to explain the electrochemical behaviour of solutions of HF–H2O.

Kx-ray spectra of solid and gaseous fluorine compounds excited by 2-MeV/amu Ar and Mg ions

The $K\ensuremath{\alpha}$ satellite and hypersatellite spectra of alkali-metal and alkaline-earth fluorides, excited by 80-MeV Ar ions, and the $K\ensuremath{\alpha}$ satellite spectra of a variety of gaseous fluorine compounds, excited by 48-MeV Mg ions, have been measured with a curved-crystal spectrometer. Analysis of these spectra using primary vacancy distributions deduced from spectra of Ne and HF, excited by the same projectiles, yielded rate constants for $L$-vacancy filling. The rate constants obtained from the satellite and hypersatellite distributions of the solid compounds are about the same (30\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ a.u.), but those obtained for the gaseous compounds are much smaller. A two-step mechanism involving electron transfer from outer levels of surrounding atoms to high-$n$ states of the target atom, followed by subsequent $L$ Auger decay is proposed.

Application of the Protonic Model Potential Approach to the Infrared Spectra of HX and Hydrogen Bonded HX−2 Species

AbstractThe application of the protonic model potential approach to calculations of the infrared spectra of HF, HCl, HF−2, and HCl−2 is examined and compared with experimental results.

K-shell excitation of HF and F2studied by electron energy-loss spectroscopy

The fluorine K-shell (1s) excitation spectra of HF and F2 have been studied by small-angle inelastic scattering of 2.5 keV electrons. The F2 spectrum exhibits a dramatic 1s to sigma * shape resonance 14.5 eV below the F 1s ionisation threshold which is qualitatively different from the 1s to sigma * transitions observed in all other first-row diatomics. An empirical correlation between experimental term values for both sigma * and pi * K-shell shape resonances and the sum of the atomic numbers of the heavy atoms in a series of first-row molecules is demonstrated and tested with respect to the energy of the 1s to sigma * transition in F2. The sigma * and pi * energies of a variety of molecules have been predicted using this relationship. In contrast to F2, the HF spectrum is more atom-like, exhibiting a moderately intense 1s to sigma * transition followed by the np Rydberg series. The equivalent-core analogy is applied to the HF and F2 results to predict excitation and ionisation energies of NeH and NeF.

XPS valence bands of Ti, Zr, Nb, Mo and Hf

The XPS valence band spectra of polycrystalline Ti, Zr, Nb, Mo and Hf have been measured with a resolution of 0.6 eV. The spectra were compared with theoretical densities of states. Good agreement is achieved if the partial densities of states are considered and a many body line shape function and life time broadening are taken into account. The sigularity index α determined at various core lines as well as the experimentally determined relative valence band cross sections are reported.

The energy distributions of atoms sputtered from HfC

The energy spectra of Hf and C atoms sputtered from an HfC target with a 6 keV Xe + beam have been measured. It was found that the target constituents of widely different masses were sputtered with energy distributions of the same form. The results are compared with the collision cascade theory for compound targets.

On resonances in HF

The author discusses a probable explanation of the totally inconsistent nature of some previously published Feshbach resonance spectra of hydrogen fluoride which has been provided by the recent work of Brion and Hitchcock (1980). He has obtained new electron transmission spectra of HF in the energy range 12.8 to 16.0 eV, which confirm the earlier HF- resonance data of Spence and Noguchi (1975) and which reveal several previously unobserved resonance structures. These new structures are energetically coincident with the higher lying members of a series of peaks recently found in the F-/HF dissociative attachment cross section. He explains the anomalous scattering from the HF-2 Pi ( nu =0) resonance level in terms of the mixing of the b 3 Pi and B 1 Sigma parent Rydberg states which has been observed in optical absorption spectra. Finally, he points out a possible mechanism for a Lyman- alpha laser.