Calculation of molecular constants for the X 1Σ g + , A 1Σ u + , B 1Πu, and a 3Σ u + electronic states of 39K2

The molecular constants are calculated for the X ¹Σ _g ⁺ , A ¹Σ _u ⁺ , B ¹Π_u, and a ³Σ _u ⁺ and electronic states of a potassium dimer. The wave functions and vibrational energies necessary for calculating the molecular constants are determined by solving the radial wave equation with the use of potential energy curves constructed by the semiempirical method. The vibrational terms, the rotational constants, and the centrifugal distortion constants calculated from the potential curves are compared with those determined from the experimental data.     

Lifetimes,population and deactivation mechanisms of theC 1 ∏ u , 23 ∏ g and 21∑ u + states of Na2

The UV and visible fluorescence of Na₂ molecules in a heat-pipe, excited by the frequency doubled radiation of a tunable mode-locked cavity-dumped cw dye laser was observed through a monochromator, using time-resolved single-photon counting. The effective lifetimes of the directly excitedC ¹ _u state and the collisionally populated 2³ _g and 2¹ _u ⁺ states have been measured as a function of sodium-vapor pressure and argon pressure which yields the radiative lifetimes, the population mechanisms and the collisional quenching cross sections of the three states.     

Perturbation Facilitated Optical-Optical Double Resonance spectroscopy of the 6Li233Σg+, 23Πg, 13Δg,b3Πu,and a3Σu+ states

The technique, Perturbation Facilitated Optical-Optical Double Resonance, has provided spectroscopic access to and molecular constants for the 3³Σ_g⁺ (v = 1–9), 2³Π_g (v = 0–24), 1³Δ_g (v = 3–14), b³Π_u (v = 0–17), and a³Σ_u⁺ (v = 0–6) states of the ⁶Li₂ molecule. Perturbation Facilitated Optical-Optical Double Resonance takes advantage of two weak spin-orbit perturbations, A¹Σ_u⁺ (v = 2, J = 33) ∼ b³Π_u (v = 9, F₁, N = 32) and A¹Σ_u⁺ (v = 9, J = 20) ∼ b³Π_u (v = 15, F₁, N = 19), to excite from X¹Σ_g⁺ (v = 0 or 1) into single rotation-vibration levels of ³Λ_u (F₁ fine structure component only) via the spin-mixed intermediate levels. The ³Λ_u (F₁ only) states are sampled in resolved fluorescence spectra from Perturbation Facilitated Optical-Optical Double Resonance-populated ³Λ_g levels.     

B 2Σ u + excited states of the N + 2 ion and the electron temperature in the discharge afterglow of an Ar-N2 mixture

The electron energy distribution function in the afterglow of a low-pressure discharge in an Ar-N₂ mixture was experimentally found. The values of electron temperature were determined. At the initial stage of plasma decay, the electron temperature was shown to be close to the nitrogen vibrational temperature. A study was made of the afterglow observed in the bands of the first negative system of N ₊ ² , and it is shown that this afterglow may be attributed to collisions of argon ions with nitrogen molecules found on higher vibrational levels.     

Formation of N2 C3Πu and B3Πg by dissociative recombination of Ar 2 + in Ar+N2 early afterglow

The hf pulse excited Ar + N₂ mixtures and early afterglow are investigated at total pressures from 266 to 1995 Pa using nitrogen of 0·05–0·5% concentration. The time-resolved intensity of Ar I atomic lines and N₂ (2nd pos., 1st pos. and 1st neg.) band systems exhibit an intense early afterglow (0·3 ms). Both the decay of electron densityn _e and that of molecular Ar ₂ ⁺ ions and enhancement of coefficient of dissociative recombination due to electron temperature decrease after the pulse lead to the formation of characteristic secondary maximum of Ar I spectral line and N₂ molecular band intensities in the momentt _m after cut-off the pulse. The values oft _m(B³_g)>t _m(C³_u)>t _m(Ar I) decrease with increasing total pressure and increase with growing concentration of N₂ in Ar. In the afterglow period the Ar ₂ ⁺ dissociatively recombine in 5p and 4p Ar states. As a result of radiative transitions the metastable Ar (³P_2,0) atoms are formed which consequently due to collisions with N₂ molecules create electronically excited N₂. With increasing nitrogen concentration this effect becomes less pronounced and at concentration of N₂ greater than 0·5% it is negligible.     

Interaction of Zn atoms in the 1 S and 3 P states with N2 molecules in the X 1Σ g + and A 3Σ u + states at moderate distances between the atom and molecule

An asymptotic method was used to derive analytical expressions for the matrix elements of interaction between the N₂ molecule in the X ¹Σ _g ⁺ and A ³Σ _u ⁺ electronic states and the Zn atom in the ¹ S and ³ P states. Quadrupole-quadrupole, dispersion, and exchange interactions were taken into consideration. The character of the set of diabatic vibronic potential energy surfaces of the system suggests that the energy transfer in the process N₂(A ³Σ _u ⁺ ) + Zn(¹ S) → N₂(X ¹Σ _g ⁺ ) + Zn(³ P) may prove to be rather effective.     

Molecule opacities of X~2Σ~+, A~2Π, and B~2Σ~+ states of CS~+

Carbon sulfide cation(CS~+) plays a dominant role in some astrophysical atmosphere environments. In this work, the rovibrational transition lines are computed for the lowest three electronic states, in which the internally contracted multireference configuration interaction approach(MRCI) with Davison size-extensivity correction(+Q) is employed to calculate the potential curves and dipole moments, and then the vibrational energies and spectroscopic constants are extracted. The Frank–Condon factors are calculated for the bands of X~2~+Σ~+–A~2Π and X~2Σ~+–B~2Σ~+systems, and the band of X~2Σ~+–A~2Π is in good agreement with the available experimental results. Transition dipole moments and the radiative lifetimes of the low-lying three states are evaluated. The opacities of the CS~+ molecule are computed at different temperatures under the pressure of 100 atms. It is found that as temperature increases, the band systems associated with different transitions for the three states become dim because of the increased population on the vibrational states and excited electronic states at high temperature.     

Polarization spectroscopy of Na2 A1Σu+-b3Πu ← X1Σg+ intercombination bands

The A¹Σ_u⁺ ∼ b³Π_u perturbation of Na₂ in several high vibrational levels has been studied by polarization spectroscopy. Deperturbed molecular constants are given for the mutually interacting v_A = 26 ∼ v_b = 28 and v_A = 34 ∼ v_b = 34 vibrational levels.     

Ab initio nonadiabatic calculation of the sensitivity coefficients for the X 1Σ g + → B 1Σ u + ; C 1Πu lines of H2 to the proton-to-electron mass ratio

Ab initio nonadiabatic calculations of the wavelengths λ_ij of the individual lines of the Lyman X ¹Σ _g ⁺ → B ¹Σ _u ⁺ and Werner X ¹Σ _g ⁺ → C ¹Π_u series of molecular hydrogen and corresponding sensitivity coefficients K _ij = dlnλ_ij/dlnγ have been performed. These quantities are necessary for testing a possible change in the proton-to-electron mass ratio γ = m _p/m _e in the process of cosmological evolution. The basic contribution to K _ij comes from the difference between the average kinetic energies of vibrations of combined states. Nonadiabatic interactions are important for a small number of locally-perturbed rovibrational levels of the B ¹Σ _u ⁺ and C ¹Π _u ⁺ states, for which change in K _ij that is caused by nonadiabatic effects reaches 14%, which can lead to a significant systematic shift in the estimate of the parameter γ.     

Weathering of Martian and Earth surface studied by Mössbauer spectroscopy

Martian regolith and Earth’s basaltoid samples have been investigated by means of Mössbauer spectroscopy. The identification of the same minerals: olivine, pyroxene, magnetite, hematite and confrontation of the Fe^3?+?/Fe^2?+?, Fe^3?+?/Fe_tot, Fe^2?+?/Fe_tot ratios are presented. Co-existence of olivine and hematite in Martian regolith, absent in presented by authors terrestrial samples has been tentatively explained.     

Zn-substitution effects on the low-energy quasiparticles in Bi2Sr2CaCu2O8+δ studied by angle-resolved photoemission spectroscopy

We have performed high-resolution angle-resolved photoemission spectroscopy on Bi₂Sr₂Ca(Cu_1−xZn_x)₂O_8+δ (x=0.0, 0.05) to study the Zn-substitution effects on the low-energy quasiparticles. We found that the Zn substitution causes the reduction of the quasiparticle intensity and the superconducting gap, while it does not affect the normal-state band dispersion, the Fermi surface, or the quasiparticle lifetime. This indicates that the Zn substitution locally destroys or hinders the superconducting pairing and as a result decreases the superfluid density, but does not affect the long-range coherence among quasiparticles.     

Investigation of N 2 + (C 2Σ u + → X 2Σ g + fluorescence excited through auger decay of the 1s −1π* resonance

A theoretical investigation of N ₂ ⁺ (C ²Σ _u ⁺ → X ²Σ _g ⁺ molecular fluorescence excited through the Auger decay of the 1s ^?1π* resonance is carried out. The fluorescence cross sections are calculated with due regard for the dependence of the matrix element of the C → X dipole transition on the internuclear distance, the interference between channels of excitation via different vibrational levels v _r of the 1s ^?1π* resonance, the rotational structure of the fluorescence band, and the predissociation of the N ₂ ⁺ C ²Σ _u ⁺ v′ ≥3) states. The calculated cross sections are in good agreement with the experimental results of recent measurements. The results of the calculations have demonstrated that the observed dependence of the cross section of the (C ²Σ _u ⁺ (v′) → X ²Σ _g ⁺ (v″) fluorescence on the excitation energy and the fluorescence wavelength for a group of bands with equal values of the difference Δv = v′ ? v″ is associated with transitions between the vibrational levels of the electronic states involved in the excitation and subsequent cascade decay of the 1s ^?1π* resonance: N₂ (v ₀ = 0) → N*₂(1s ^?1π*(v _r)) ? N ₂ ⁺ : (C ²Σ _u ⁺ (v′) → X ²Σ _g ⁺ (v″).     

The vibrational structure of bromocyanoacetylene cation in the X̃2π and Ã2π electronic states studied by emission and laser exci

The vibrational frequencies of bromocyanoacetylene cation in its ground and first excited electronic states have been obtained by recording and analysing the emission and laser excitation spectra of the òπ-X̃²π transition. In the emission experiments the ions are produced rotationally cooled to ca. 10 K by means of a supersonic free jet and in the laser excitation measurements to ca. 100 K by Penning ionisation followed by collisional relaxation. The resulting narrowing of the vibronic bands in the spectra is such that the vibrational frequencies of most of the fundamentals could be inferred to within ± 2 cm⁻¹.     

Time spectroscopy in theA 1 ∑ u + state of Li2. Perturbations by thea 3Π u state

We have employed time-resolved LIF spectroscopy in order to investigate perturbations in theA ¹ ∑ _u ⁺ state of the three isotopic Li₂ molecules. After a systematic check of more than 2000 individual rotation-vibration levels, 46 levels were found whose anomalous lifetimes can be interpreted by perturbations with thea ³ Π _u state. As almost all perturbed levels possess shortened lifetimes the predissociating nature of thea ³ Π _u state, caused by interaction with thex ³ ∑ _u ⁺ continuum, is revealed. On the basis of the Kovács-Budo theory of accidental predissociation we have fitted the molecular constants of thea ³ Π _u state, thex ³ ∑ _u ⁺ potential curve and the electronic parts of the perturbation matrix elements do that the observed lifetimes of all levels in the 78 investigatedA ¹ ∑ _u ⁺ ?a³ Π _u term-crossing regions can be understood.     

Iron-metal multilayers studied by Mössbauer spectroscopy,RBS and X-ray diffraction

Fe/M (M = Ag, Zn and Sn) multilayers prepared by a vacuum evaporation method are studied by Mössbauer spectroscopy (MS), Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD). For the case of an M = Ag multilayer, MS reveals that Fe in the multilayer remains as an-phase down to the layer thickness of 10 nm. This result is in agreement with the RBS result that Fe and Ag form a completely discrete layer structure without any mutual mixing. For the case of M = Zn and Sn, RBS reveals that a considerable mixing has taken place between Fe and Sn during the specimen preparation. MS on Fe/Sn specimens with different layer thickness shows that an alloy phase of about 5 nm thickness is formed at the interface. Structural as well as magnetic properties of the alloy phase are discussed based on MS at different temperatures and on reported results of the intermetallic compound FeSn.     

Relative probabilities of spontaneous transitions in v″ progressions of the G1Σ g + , v′→B 1Σ u + , v″ bands of the H2 molecule

The probabilities of spontaneous transitions in v″ progressions of the G ¹Σ _g ⁺ →B ¹Σ _u ⁺ bands of the H₂ molecule (the 3D→2B electronic transition in notations of G.H. Dieke) are, for the first time, experimentally studied. The line strength ratios were measured for 78 G ¹Σ _g ⁺ , v′, J′→B ¹Σ _u ⁺ , v″, J″ electronic-vibrational-rotational spectral lines having a common upper level but belonging to different bands of v″ progressions (the vibrational branching coefficients). For this purpose, the intensities of lines of the P and R branches, emitted by a low-pressure plasma and corresponding to different values of the rotational (J′=0–11) and vibrational (v′=0–3 and v″=0–7) quantum numbers, were used. It was found that the changes in the vibrational branching coefficients with variation of v′ and v″ are significant (up to a factor of 20). For most bands studied, the dependences of the vibrational branching coefficients on the rotational quantum number J′ of an upper level are rather weak and do not exceed 30%. It was established that the difference between the experimental values of ratios of the vibronic transition probabilities (summed over J″) and the results of calculation in the adiabatic approximation strongly depends on v′, reaching a factor of 25 for a transition from the v′=2 level. At the same time, the discrepancy between the experimental data and the results of nonadiabatic ab initio calculations lies between 1.0 and 2.3.