M4,5N4,5N4,5 auger electron spectrum of Ba metal

The Al Kα excited M_4,5N_4,5N_4,5 Auger spectrum of Ba has been measured from the metallic sample evaporated on a Ag substrate. The spectrum has been decomposed into individual line components after the background subtraction. The decomposed spectrum has been compared with the theoretical spectrum calculated for the 4d^?2 final state configuration in the mixed coupling scheme applying jj-coupling for the initial state and intermediate coupling for the final state. The most prominent structure of the spectrum shows the two 4d-hole coupling, but the structure which is caused by the Auger transitions M_,45N_2,3V has also been observed. The screening of the core holes in Ba metal seems to be produced by (5d6s) electrons. The simple excited atom model HF-calculations give an Auger kinetic energy shift (metal-free atom) of 16.7 eV, which is comparable to the experimental value 14–18 eV.     

Study of L2,3M4,5M4,5 Auger spectra of Zn and Cu in molecular ZnCl2 and (CuCl)3 vapours

L_2,3M_4,5M_4,5 Auger electron spectra of Zn and Cu have been measured in molecular ZnCl₂ and (CuCl) ₃ vapours. The spectra have been analyzed and compared with the corresponding free-atom spectra. It is found that the main features of the spectra are atomic-like. The energies are shifted by 0.55 eV in ZnCl₂ and by 3.2 eV in (CuCl)₃ towards higher kinetic energy compared with the corresponding free-atom spectra. For the intensity ratios between the L₃ and L₂ groups, the values 2.8 and 3.7 are obtained for Zn and Cu, respectively. These intensity ratio, together with energy considerations based on free-atom Dirac—Fock calculations and observed Auger shifts, indicate that the L₂L₃M_4,5 Coster—Kronig process is energetically possible in (CuCl)₃ molecular clusters but not in ZnCl₂. The satellite structure in the spectra studied also supports this conclusion.     

Solid-state shifts in the L3M4,5M4,5 Auger spectra of the elements Cu TO Se

The kinetic-energy shifts between atomic and solid-state L₃M_4,5M_4,5 Auger electron spectra of Cu, Zn, Ga, Ge, As, and Se are determined with the aid of semiempirically calculated atomic and experimental solid-state Auger energies. The shift values are calculated by applying the thermochemical model to the Auger process. Good agreement is found between the calculated and experimental values.     

Comparison of light rare earths N4,5-level soft X-ray and auger electron appearance-potential spectra

Appearance-potential Spectroscopy (APS) probes the binding energy of core levels and local conduction band states of atoms in the surface region. Soft X-ray APS (SXAPS) and Auger electron APS (AEAPS), respectively, measure the differential X-ray fluorescence and secondary electron yields as a function of incident electron energy. We have obtained the N_4,5-level SXAPS and AEAPS spectra of La, Ce, Pr, Nd and Sm metals. Both spectra exhibit multiplet structure below the expected 4d excitation threshold and a broad, 10–20 eV wide peak above the threshold followed by small peaks of decreasing intensity. The data are used to gain an understanding of the decay mechanism following the excitation of the core levels in these spectroscopies. The strong similarity observed between the SXAPS and AEAPS indicates that the characteristic emission and not the bremsstrahlung dominates the spectral lineshape in APS.     

The M4,5- VV Auger spectrum of silver: An interpretation based on quasi-atomic final states

The M_4,5- VV Auger spectrum of silver has been studied under high-resolution conditions. The relative energies and intensifies of the Auger lines calculated for a 4 d⁸ final state configuration account well for the experimental spectrum. This quasi-atomic behaviour is due to the fact that the effective two-hole Coulomb interaction is larger than the bandwidth. The influence of the solid state on the width of the Auger lines is discussed.     

Laser Stark spectroscopy of the ν4 band of CH3C15N: Fermi resonance with 3ν83

Laser Stark spectra for the ν₄ band of CH₃C¹⁵N have been measured by using CO₂ and N₂O lasers. Almost 650 resonances have been assigned to about 140 ro-vibrational transitions with J′ ≤ 34 and K ≤ 11. An anomaly of the rotational structure around K = 7 has been proved to be due to a Fermi interaction by analyzing each K subband separately. Observed data have been fitted to a model which includes ν₄-3ν₈³ Fermi coupling by the method of least squares. The standard deviation of observed from calculated frequencies is 4.6 MHz. Molecular constants derived are also listed.     

New infrared integrated band intensities for HC3N and extensive line list for the ν5 and ν6 bending modes

The infrared spectrum of cyanoacetylene (also called propynenitrile) has been investigated from 400 to 4000 cm⁻¹ at a resolution of 0.5 cm⁻¹. Integrated intensities of the main bands and a number of weaker bands have been obtained with an uncertainty better than 5%. Inaccurate values in previous studies have been identified in particular concerning the intensity of the strong ν₅ stretching band at 663.2 cm⁻¹. Former results on the temperature dependence of integrated intensities have also been revisited.Synthetic spectra calculation has been performed for the ν₅ and ν₆ bands on the basis of the best available high resolution data. It has been shown that the GEISA line parameters for HC₃N are not sufficient to reproduce the band intensities and some hot band features observed in our experimental spectra at room temperature. As a first step, the model spectra has been improved by including a number of missing hot subbands and by calculating accurately the hot band relative intensities. Finally, a perfect agreement between calculated and observed spectra was achieved on the basis of a global analysis of HC₃N levels up to 2000 cm⁻¹ combined with the new integrated intensity measurements. A new extensive line list for the ν₅ and ν₆ bending modes of HC₃N has been compiled.     

Line parameters and shapes of high clusters: R branch of the ν3 band of CH4 in He mixtures

The IR absorption spectra of CH₄ in pure gas and in mixture with helium were studied in the region of ν₃ band at higher J line clusters R(17)-R(22). The frequencies and intensities of rotation-vibration lines were estimated from the experimental spectra at Doppler shape conditions. The line frequencies and intensities were calculated and used for the attribution of overlapped lines in clusters. The calculated line intensities are close to the experimental values. The calculated frequency structure of the higher J manifolds are somewhat wider than the observed one. The shapes of helium-broadened line clusters were compared with those calculated accounting for line mixing. The relaxation matrix W, which is necessary in shape calculations, was constructed using semiclassical collision rate constants. The calculated shapes are in satisfactory accordance with the measured ones.     

High-resolution infrared atmospheric spectra of ozone in the 10-μm region: Analysis of ν1 and ν3 bands-assignment of the (ν1 + ν2) − ν2 band

1988 lines of ozone have been observed in the atmospheric spectrum in the region 1060 to 1220 cm^?1, 1394 of them have been assigned to the ν₁ band, and 480 to the ν₃, particularly corresponding to ΔK_?1 = 2. The analysis has been performed using the Watson Hamiltonian, taking account of the strong Coriolis coupling between the 001 and 100 levels. The constants for the latter two states, the spectra and a listing of the observed and calculated wave-numbers, with their assignment, are given. In addition, 114 lines of the “hot” band (ν₁ + ν₂) ? ν₂ have been observed and assigned and are reported.     

High resolution spectroscopy of the ν4 band of methane

The fundamental ν₄ band of methane in the 1292–1306 cm^?1 region has been investigated at high resolution using a tunable diode laser. Line center frequency separations and relative line intensities have been measured. A comparison is presented with recent theoretical calculations showing a satisfactory agreement both in line frequency assignment and in line intensity.     

Calculated energy levels and intensities for the ν1 and 2ν2 bands of HDO

A Hamiltonian taking explicitly into account both Fermi and Coriolis interactions has been set up for triatomic molecules of symmetry C_s and used to reproduce, very satisfactorily, the available rotational energy levels of the {(100), (020)} interacting states of HDO, providing us with realistic wavefunctions as well as precise rotational constants and vibrational energies. Then, to calculate line intensities, these wavefunctions were used together with suitably chosen transition moment operators expanded up to degree 2 in $\text{J}$ and having the correct symmetry in the C_s group, leading to hybrid bands of both A and B type., Using this formalism, it has been possible to determine, from the fit of the existing experimental intensities, the coefficients appearing in the expansions of the transition moment operators of the 2ν₂ and ν₁ bands of HDO. In this way, we have improved upon the F-factor formalism which needs much more parameters to reproduce the line intensities with the same precision. Finally, using the transition moments as well as the wavefunctions and energy levels deduced from the diagonalization of the Hamiltonian matrix, we have calculated the whole spectrum of the ν₁ and 2ν₂ bands of HDO.     

Korrelationseffekte in den Auger-Spektren von Edelgasen

The possibility of studying correlation effects through Auger electron spectrometry has been shown recently by Krause, Carlson and Moddeman in the case of theK Auger spectrum of neon. As a further example we have measured theM _4,5 Auger spectrum of krypton with high resolution. Correlation effects have been found via the strong deviations of relative intensities of Auger diagram lines (e.g.M _4,5 N ₁ N _2,3(¹ p ₁)) from theoretical values and via the occurence of double Auger transitions, where one electron is emitted and another is excited. A critical examination of high resolution Auger spectra of noble gases, which has been measured so far, has shown that several non diagram lines can be assigned to double Auger transitions of the above kind.     

S0 and S1 spectroscopy of jet cooled 9-cyano-10-methylanthracene: The methyl group as a molecular rotor

Jet-cooled fluorescence excitation and dispersed fluorescence spectra of 9-methylanthracene (MA), 9-cyanoanthracene (CA) and 9-cyano-10-methylanthracene (CMA) have been measured. The spectra of MA and CMA near the S₀-S₁ origin reveal a prominent torsional progression due to the hindered methyl group rotation and its torsional vibration against the aromatic ring frame. Additionally, the laser induced fluorescence LIF excitation spectrum of CMA shows the splitting of many vibrational modes.Observed positions and relative intensities of the methyl internal rotational bands were interpreted in terms of transitions calculated based on the quantum mechanical one-dimensional rotor. The low-frequency vibrational bands were interpreted also with the all electron quantum mechanical calculations within the RHF/6-31G(d,p), CIS/3-21G and CIS/6-31G(d,p) approximations. It is predicted that in the case of MA the eclipsed geometry (one C-H in the plane of the ring) is most stable in both S₀ and S₁ states. Conformation of the methyl group in CMA is suggested to change upon S₁ ← S₀ excitation (π/12 phase shift of the methyl group). The predicted energy barrier for methyl group rotation in the S₀ state of CMA is considerably higher (72 cm⁻¹) than that in the S₁ state (22 cm⁻¹). Following the present quantum mechanical calculations, the carbon atom of the methyl group belongs to the aromatic plane in the S₀ ground state but it deviates from this plane in the S₁ excited state. These in turn suggest that the calculated barrier for methyl group rotation in CMA has a 6-fold symmetry in the S₀ ground state and roughly a 4-fold symmetry in the S₁ state.     

Search for correlation effects in theM 4, 5 N 4, 5 N 4, 5 Auger spectrum of xenon

TheM _{4, 5} N _{4, 5} N _{4, 5} Auger spectrum of xenon has been measured with high resolution. Theoretical line intensities and relative line energies for this spectrum have been calculated applyingjj coupling to the initial states and intermediate coupling and configuration interaction to the final states. Two facts indicate that correlation effects are only small in the present case: The application of configuration interaction gives only small changes in line intensities and the experimental line intensities are found to be in good agreement with theoretical results, calculated without configuration interaction.     

High resolution infrared spectrum of the ν2 + ν3 and ν1 + ν2 bands of ozone

The vibration-rotation bands ν₁ + ν₂ and ν₂ + ν₃ of ozone appearing in the 5.7 μm region have been recorded at a resolution of 0.019 cm^?1 with a SISAM spectrometer. The rotational levels of the (110) and (011) vibrational states have been fitted using a Hamiltonian which takes into account the Coriolis interaction between these two states. The rotational and coupling constants deduced from this study have been used to calculate a list of the vibration-rotation lines which is of interest for high resolution studies of atmospheric spectra in the 1670–1890 cm^?1 region.     

The ν2 + ν4 and 2ν2 isotropic Raman bands of 12CH4

The purely isotropic Raman spectrum of the ν₁ band, the ν₂ + ν₄ band (enhanced through interaction with ν₁), and the 2ν₂ band of ¹²CH₄ was obtained with a spectral resolution of 0.30–0.35 cm^?1 from exposures with different orientations of the linearly polarized exciting light. The ν₂ + ν₄ and 2ν₂ bands show partially resolved rotational structure. The spectra are interpreted in terms of a model which takes explicitly into account vibrational and rovibrational interactions with other vibrational states, using molecular constants determined primarily from infrared spectra. The computed contours are in excellent agreement with the experimental ones and the observed and calculated peak wavenumbers agree within one tenth of the spectral resolution limit, except for a small region near the ν₁ band. The good overall agreement represents an independent check on the overall correctness of the previously reported molecular constants. A detailed discussion is given of the contributions to the intensities of individual transitions from the three transition moment matrix elements, which in an isolated-band model are the intensity parameters of the ν₁, 2ν₄, and 2ν₂ isotropic bands, respectively.     

Analysis of the ν9 band complex of dicyanoacetylene and application of a theory of relative intensities to all subbands

The band complex near 107 cm⁻¹ consisting of the fundamental ν₉ of dicyanoacetylene (NC-CC-CN) and its associated hot bands has been analysed from the high resolution infrared spectrum. It turned out that two sets of bands from levels (v₉=0-8) and (v₇=1; v₉=0-5) were observable. Including cases where separate e- and f-transitions have been observed, the total number of identified series exceeds 90. The calculations were made with a global rovibrational analysis program adapted for linear sixatomic molecules. We have developed general procedures for calculation of the relative intensities of all allowed transitions between two vibrational polyads in the electronic ground state of a linear molecule, taking into account the wavefunction mixing due to essential or accidental resonances. This supports the assignment procedure in the present case and allows us to understand the dramatic effects on the intensities of different subbands. A good agreement between calculated and observed intensities is obtained with one single intensity parameter for the whole set of subbands.     

Diode laser measurements of NH3, ν2-band spectral lines

High-resolution absorption spectra of the NH₃, ν₂ band in the 800- to 1200-cm^?1 region have been measured using ir tunable diode lasers. One hundred lines of 18sP-, aP-, aQ-, sQ-, aR-, and sR-branch multiplets have been resolved. Absorption line separations have been measured and line frequencies assigned using high-precision literature data. For all the transitions observed, relative line intensities have been calculated and compared to literature data; for three lines, the absolute intensities have been measured.     

Self-broadening parameters in the ν3 band of 14N216O

Self-broadening parameters of lines belonging to the R branch of the N₂O ν₃ band up to R(70) have been measured using a vacuum grating spectrometer. Line intensities were also deduced from the deconvoluted spectrum. Interpretation of the experimental results is achieved using two semiclassical models.     

Laser stark spectroscopy of the ν4 + ν8 − ν8 band of CH3C15N: Fermi resonances with 4ν84, 4ν82, and (ν7 + ν8)2

Laser Stark spectra for the ν₄ + ν₈ ? ν₈ parallel band of CH₃C¹⁵N were measured by using CO₂ and N₂O lasers in the 10-μm region. About 300 resonances have been assigned to 102 rovibrational transitions with J′ <- 16 and ?9 ≤ kl ≤ +9. Anomalies observed around kl = ?6 and +8 were proved to be due to the Fermi interactions with 4ν₈² and 4ν₈⁴, respectively. Another Fermi interaction with (ν₇ + ν₈)² was necessary to account for the anomaly around kl = ?6. Observed data were analyzed by the method of least squares, and precise molecular constants have been obtained.