Autoionizing and highly excited states in the spectrum of triply ionized tin Sn IV

Transitions from autoionizing states in the spectrum of Sn IV in the range 200–630 Å, occurring due to the excitation of electrons from the inner 4d ¹⁰ shell, are investigated with high resolution. The transitions from the 4d ⁹5p ², 4d ⁹5s6p, and 4d ⁹5snf (up to n = 9) configurations are identified and their autoionization widths are measured. Transitions from the highly excited 4d ¹⁰ ns (n = 8–10), 4d ¹⁰6p, and 4d ¹⁰7d configurations are also revealed and the ionization potential of Sn IV is refined. The data obtained are compared with the results of calculations by the Hartree-Fock and semiempirical methods.     

Electron-transfer-mediated decay and interatomic Coulombic decay from the triply ionized states in argon dimers

We report the first observation of electron-transfer-mediated decay (ETMD) and interatomic Coulombic decay (ICD) from the triply charged states with an inner-valence vacancy, using the Ar dimer as an example. These ETMD and ICD processes, which lead to fragmentation of Ar(3+)-Ar into Ar(2+)-Ar(2+) and Ar(3+)-Ar+, respectively, are unambiguously identified by electron-ion-ion coincidence spectroscopy in which the kinetic energy of the ETMD or ICD electron and the kinetic energy release between the two fragment ions are measured in coincidence.     

Energies and Auger widths of the triply excited states of He-

Some triply excited states of He^- ion are studied using the saddle-point complex-rotation method. The energies and Auger widths of these resonances are calculated with the relativistic corrections and mass polarization taken into account. The total Auger width is obtained by coupling the important open channels and summing over the other channels. These results are in good agreement with other theoretical and experimental data in the literature.     

离化态氧原子的激发光谱的研究

在串列加速器上利用束箔-方法和带有CCD的光谱仪测量装置,在2～2.5 MeV束能下采用Spectrapro-500i光谱单色仪,在200 nm～800 nm波长范围测量了离化态氧原子的500多条光谱线.实验发现了许多弱谱线的跃迁能级,这些跃迁谱线以前带有光电倍增管或电子倍增器的单色仪很少测量到这些弱谱线的跃迁.本文报道在200nm～300nm范围已确定的部分光谱线和跃迁能级,这些跃迁主要属于OⅡ到OⅣ离化态原子的3p 4S3/2,3p 2 S1/2,3p 4P1/2,3p 4P3/2,3p 4P 5/2,3p 2D3/2,3p 2D5/2,3d 2D5/2,3d 2F5/2,3d2F7/2,4p 3D1,4p 3D2,5d 2D5/2等能级的跃迁,光谱分辨0.015 nm.     

Energies and widths of triply excited states of lithiumlike oxygen and neon

Seven low-lying triply exited states of lithium-like oxygen and neon are calculated with the multichannel saddle-point and saddle-point complex-rotation methods. The term energies are given for these excited states, along with level shifts and partial Auger widths from dominant decay channels. The mass polarization effect and relativistic corrections are included. The radiative transition rates are also calculated. These results are compared with other theoretical data in the literature. Received: 25 May 1998 / Revised: 28 July 1998 / Accepted: 25 August 1998     

Highly excited rovibrational states of HNC

The emission spectrum of HCN has been recorded at 1463 K using hot gas molecular emission (HOTGAME) spectroscopy in the wavenumber region of 2900–3500 cm⁻¹ with a resolution of 0.01 cm⁻¹. The dense emission spectrum was analyzed with the spectrum analysis software SyMath™ implemented in the Mathematica™ computer algebra system. This work reports the analysis of the band series up to v₂ = 8 and of the band series up to v₂ = 6.36 rovibronic (v₁, v₂, l, e/f, v₃) substates of HCN including all l = 0, 2, 4, 6, 8 sublevels of the highly excited bending combination mode have been characterized for the first time and for the 22 known vibrational sublevels it was possible to improve the existing spectroscopic constants substantially. 18 (v₁, v₂, l, v₃) vibrational sublevels are located for the first time relative to the 00⁰0 state. The analysis reported here includes rovibrational states up to very large rotational excitations of J = 60–80. For the combination states the rotational states have been determined up to J = 86 which corresponds to 7000 cm⁻¹ rotational excitation energy, this state is only 2000 cm⁻¹ below the isomerization barrier. It was possible to determine for the first time the L_v high order rotational constant for many states reported in this work.     

TiVI真空紫外光谱

用1m法向入射光谱仪观察三电极真空火花发射的Ti五次离化光谱。在24～200nm波段内观察到157条TiVI的新谱线。根据新归属的TiVI谱线定出11个新能级,并对5个有疑问的能级值作了修正。     

Highly excited alpha-cluster states in 34S

The elastic-scattering reaction ³⁰Si + $ \alpha$ was studied using the Thick Target Inverse Kinematics technique. Data were taken at a ³⁰Si beam energy of 150MeV in a reaction chamber filled with ⁴He gas, corresponding to the excitation region of 12-24MeV in ³⁴S . The data were treated in the framework of a simplified R -matrix approach, and energies, widths and spin assignments were obtained for 111 resonances in an approximative manner. The structure is discussed within the concept of $ \alpha$ -cluster structure in the quasi-continuum of ³⁴S and is compared to recent data for ³²S .     

Doubly excited states in the beam-foil Li spectrum

Beam-foil excited spectra of Li atoms and ions have been investigated in the wavelength range 2000–6000 Å. Line widths and lifetimes are given for the lines at 3155 Å, 3144 Å, and 5539 Å, the two latter representing transitions between doubly excited states.     

Analysis of autoionizing Rydberg states in the vacuum ultraviolet absorption spectrum of HCl and DCl

The photographic absorption spectrum of HCl and DCl above the first ionization limit (750 – 950 Å) has been analyzed. Two Rydberg series converging to the second ionization limit (²Σ⁺) have been identified. No analyzable rotational structure was observed, indicating that the autoionization rate is faster than the rotational period. The symmetries of the Rydberg states cannot be determined conclusively, but several possibilities are discussed.     

Analysis of autoionizing Rydberg states in the vacuum ultraviolet absorption spectrum of HBr and DBr

The photographic absorption spectrum of HBr and DBr above the first ionization limit (800–1000 Å) has been analyzed. No analyzable rotational structure was observed, indicating that the autoionization rate is faster than the rotational period. Two Rydberg series converging to the second ionization limit (²Σ⁺) have been identified, one with n^* = 2.75, 3.74, ,14.7, and the other with n^* = 2.35, 3.38. The symmetries cannot be determined conclusively, but the most probable assignment for the first series is 4pσ 4pπ⁴nsσ (¹Σ⁺) N = 6, 7, , 18, and for the second, 4pσ 4pπ·npσ and/or npπ[¹Σ⁺, ¹Π] N = 5, 6. Assuming that the intensity maxima assigned are band origins of vibronic states, a new ionization limit can be determined for HBr⁺(²Σ⁺): T₀ = 123 373 ± 20 cm⁻¹.     

Level structure and lifetimes of excited states in 48Ti

The properties of excited states in ₂₂⁴⁸Ti₂₆ populated by means of the ⁴⁵Sc(α, pγ)⁴⁸Ti reaction were investigated. The Doppler-shift attenuation method was employed to determine the mean lives of 16 levels up to an excitation energy of 4073 keV. Proton-γ coincidence techniques were used to record simultaneously the Doppler-shifted de-excitation γ-rays emitted at 26 and 154 degrees to the incident beam direction. A comprehensive level and decay scheme is proposed. Detailed shell-model calculations have been made of M1 and E2 transition matrix elements for depopulation of states whose lifetimes have been measured. Salient nuclear structure aspects of this “self-cross-conjugate” nucleus are examined in light of critical comparisons of measured and calculated Ml and E2 reduced transition probabilities.     

Microwave spectrum of 3-bromopropene in the excited torsional states

The microwave spectra in the excited states of the CC torsion for the ⁷⁹Br and ⁸¹Br isotopic species of 3-bromopropene were measured in the frequency region 15.3–23.7 GHz. The a-type R-branch and b-type Q-branch rotational transitions in the first and second excited states of one conformer, skew, have been assigned and analyzed. Analysis of the spectrum yields the rotational constants and the nuclear quadrupole coupling constants. From relative intensity measurements the energy differences associated with the CC torsion, between the ground and first excited state, the ground and second excited state have been found to lie 109 and 206 cm^?1, respectively.     

Grating tuned Ti:Sa laser for in-source spectroscopy of Rydberg and autoionizing states

Due to the large absorption cross section for optical transitions into Rydberg and autoionizing states compared to non-resonant ionization, these states are of particular interest for use in efficient laser resonance ionization excitation schemes as used in Resonant Ionization Laser Ion Sources (RILIS). In order to identify these atomic states extensive laser spectroscopy has to be performed. The lasers employed at TRIUMF’s laser ion source are birefringent filter tuned titanium:sapphire (Ti:Sa) lasers which are designed for long term frequency stability rather than continuous tuning. The design and characteristics of a grating tuned, high repetition rate, pulsed Ti:Sa laser for spectroscopy applications are presented. This laser allows fast scans of up to 40 THz with a laser linewidth of approximately 6 GHz. First tests were performed by scanning across the Rydberg series of gallium.     

Radiative lifetimes for excited states in doubly ionized elements (21 ≤ Z ≤ 30) of astrophysical interest

Beam-foil technique has been applied to measurements of radiative lifetimes of 23 terms or levels, all belonging to the 3dⁿ4p (n = 0 to 9) configurations, in Sc(III), Ti(III), V(III), Cr(III), Mn(III), Fe(III), Ni(III) and Zn(III). The experimental lifetimes are in good agreement with lifetimes derived from oscillator-strength calculations, based upon the scaled Thomas-Fermi method, for ultraviolet lines in the spectra of the doubly ionized transition elements.     

Microwave spectrum of methylene fluoride in excited vibrational states

The rotational spectra of ¹²CH₂F₂ in seven of the nine fundamental vibrational states and also in overtone and combination states involving the ν₄ mode were observed and assigned. Coriolis interactions between ν₃ and ν₇, ν₂ and ν₈, ν₃ and ν₉, and ν₅ and ν₇ were analyzed by using approximate expressions for the rotational levels. An effective Hamiltonian with the Coriolis term in the off-diagonal block was applied to stronger interaction between ν₃ and ν₉. Fermi resonance between ν₃ and 2ν₄ was found to be negligible. The ground state spectra of ¹²CH₂F₂ and of ¹³CH₂F₂ were remeasured to improve the accuracy of the rotational and centrifugal distortion constants. The Coriolis coupling constants and the energy differences between two vibrational levels in resonance, which were obtained through an analysis of the satellite spectra, are compared with the results derived from a normal coordinate analysis.     

Stark spectrum of barium in highly excited Rydberg states

We present observations of Stark spectra of barium in highly excited Rydberg states in the energy region around n = 35. The one-photon excitation concerns the π transition. The observed Stark spectra at electric fields ranging from 0 to 60 V·cm-1 are well explained by the diagonalization of the Hamiltonian incorporating the core effects. From the Stark maps, the anti-crossings between energy levels are identified experimentally and theoretically. The time of flight spectra at the specified Stark states are recorded, where the deceleration and acceleration of barium atoms are observed. This is very consistent with the prediction derived from the Stark maps from the point of view of energy conservation.     

The microwave spectrum of trifluoroacetonitrile in excited vibrational states

The microwave transitions J → J + 1 have been observed in the symmetric top molecule trifluoroacetonitrile, CF₃CN, for molecules excited into several of the low-lying vibrational states. Measurements made in the degenerate states v₇ = 1 v₈ = 1 have been fitted to the formula derived by Grenier-Besson and Amat (1) for transitions J → J + 1 in degenerate vibrational states of molecules with C_3v symmetry. The measurements for the state v₈ = 1 have been extended to 150 GHz where it is shown that the above formula becomes inadequate to describe accurately the observed spectrum.