Coriolis interaction in the local mode (n100;F2) combination states of GeH4

Coriolis interactions in local mode (n100) combination states of GeH₄ are studied. Three widely used local mode models, the normal mode model with Darling–Dennison resonance included (NMDD) model and the anharmonically coupled anharmonic oscillator (ACAO) model with two different kinds of bond stretching variable, were used to calculate the values of the interaction parameters. As a test of these three models, the Coriolis interaction parameters of the local mode (3100) combination bands of the ⁷⁴GeH₄,⁷²GeH₄ and ⁷⁰GeH⁴ species, recorded at a resolution of 0.015cm^-1 on a Bruker IFS120HR Fourier transform spectrometer, are compared with the calculated results. There is good agreement.     

Laser Stark spectroscopy of silyl fluoride in the 10-μm region: Analysis of the ν2 and ν5 bands

The v₂ = 1 and v₅ = 1 states of silyl fluoride are strongly mixed by Coriolis coupling. About 1100 Stark tuned resonances were measured in these bands using ¹²CO₂ and ¹³CO₂ lasers. These data were combined with 13 new millimeterwave measurements and 900 Fourier transform infrared measurements in a suitable model. Apart from the main Coriolis coupling ζ₂₅, it was necessary to include estimates of two further Coriolis terms to obtain a satisfactory interpretation of the data. Many vibration-rotation parameters and the dipole moments are determined.     

Spin alignment in the particle-rotor and cranking models

It is shown that the cranking model normally gives a smaller rotation-aligned spin for an odd quasiparticle than the particle-rotor model, especially at low rotational frequencies. The basic reason is found to be that the rotational frequency vector of the cranking model is “sharp”. This is an unphysical model property, and in the presence of a particle whose rotational motion is partly decoupled from the rotational motion of the average field its consequences become serious. A “sharp” rotational frequency corresponds to a neglect of the recoil effect that establishes coherence between the motion of the decoupled nucleon and the other nucleons and therefore is a prerequisite for the conservation of angular momentum. In conclusion the cranking model cannot be invoked to explain the so-called “Coriolis attenuation”, relative to the particle-rotor model, that is observed experimentally. Particle-rotor calculations are carried out into the backbending region of some well-deformed rare-earth nuclei, and the results indicate that the “Coriolis attenuation” effect is weak or absent at high rotational frequencies. However, the experimental $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$, unfavoured band of ¹⁶⁷Yb is found to exhibit an anomalous “downbending” behaviour.     

The influence of 1QP-state equilibrium deformations on E1 transition probabilities

E1 transition probabilities in ^{171, 173}Lu are calculated using equilibrium deformations of one-quasiparticle states deduced within the model applied. Pairing correlations and Coriolis coupling are also taken into account.     

Influence of Coriolis coupling on inelastic scattering of deuterons

Influence of Coriolis coupling on excitation of some Nilsson states in¹⁵⁵Gd,¹⁵⁷Gd and¹⁶⁷Er by inelastic scattering of 12·1 MeV deuterons is analysed. Expanded Nilsson potential with hexadecapolar deformation is used for the model calculations. Theoretical values of reduced transition probability,B(E2) are compared with experimental ones.     

Vibration-rotation spectra of CD3CCH

Rotational structure in the perpendicular fundamentals ν₆, ν₇, and ν₈, and in the parallel component of 2ν₉ of CD₃CCH are fully analyzed at a resolution of 0.2–0.3 cm^?1. The A₁-E Coriolis resonances between ν₄ and ν₇, and ν₅ and ν₈ are analyzed by computer contour simulations. These permit accurate location of the parallel fundamentals, and determination of the associated Coriolis interaction constants. The fundamental vibrations ν₅ and ν₈ in CD₃CCH lie only 4 cm^?1 apart, and constitute the closest accidental Coriolis resonance yet studied by the simulation technique. The force field of methyl acetylene, constrained according to the hybrid orbital model, is calculated, using the recently determined molecular structure, and fitting all observed data, many of which have been revised in a number of recent studies.     

High-spin states and rotation-particle coupling in 179W

The ¹⁷⁸Hf(α, 3n)¹⁷⁹W and ¹⁸¹Ta(p, 3n)¹⁷⁹W reactions are used to populate rotational states in ¹⁷⁹W. Particular attention is paid to the strongly perturbed positive-parity bands. The rotational energies within these bands are successfully explained within the unified model with pairing and Coriolis interactions included if the theoretical Coriolis matrix elements are reduced. The wave functions are calculated from a fit to the experimental energies and the theoretical and experimental transition probabilities are compared. Rotational bands built on the $\text{7}\text{2}$^?[514], $\text{1}\text{2}$^?[521] and $\text{5}\text{2}$^?[512] intrinsic states are also observed.     

Spin density polarization effects in the presence of Coriolis force on ion acoustic waves in quantum plasma

Ion acoustic solitary waves in a quantum plasma, which is slowly rotating around an axis at an angle θ with the direction of magnetic field, are investigated. Quantum hydrodynamic model is under consideration with the effects of rotations which are included via Coriolis force. Fermions are degenerate and have different spin density states, that is, up and down characterized via parameter α. Linear analysis is performed by applying Fourier transformation to derive dispersion relation. For nonlinear analysis, we apply reductive perturbation method to derive Korteweg de Vries equation (KdV). The effects of variations of Coriolis force, spin polarization, and quantum parameter on characteristics of solitary structure are discussed. These results are applicable to astrophysical and laboratory plasmas.     

The level structure of 189Os

The level structure of ¹⁸⁹Os has been studied by (d, p), (d, t) and (d, d') reaction spectroscopy at E_d = 12.1 MeV. Assignments of a number of levels at excitation energies below ≈ 1700 keV are given. The assignments are discussed in terms of a unified model based on the Nilsson model including pairing, rotational motion and attenuated Coriolis coupling. Deviations between predicted and experimental excitation energies and wave functions are generally found to be consistent with trends observed in ¹⁸⁷Os and in the odd W isotopes. Evidence for the existence of collective non-rotational states is found from the (d, d') reactions. Results of (³He, α) and high resolution γ-ray and conversion electron studies were also included at various stages of the investigation to supplement the data from the deuteron induced reactions. Comparisons between calculated and measured B(E2) values are found to indicate an intrinsic quadrupole moment of the ground-state band of ≈ 5.0 b, in agreement with values in adjacent even Os isotopes. Details of the Coriolis coupling calculations are given.     

On-line nuclear orientation of Au isotopes at KOOL

On-line low temperature nuclear orientation measurements were performed on shortlived¹⁸⁵Au,¹⁸⁶Au,^189mAu,^191mHg implanted in an iron matrix. As decay products¹⁸⁵IrFe and^191mAuFe were studied too. Besides magnetic moment determinations spectroscopic information on spin values of excited levels and mixing ratios of transitions in the daughter nuclei Pt and Au are presented. The results are interpreted in a Nilsson + Coriolis + pairing model.     

Angular-correlation study of the level scheme of 193Ir

The decay of ¹⁹³Os to ¹⁹³Ir has been studied by γγ angular correlations. Inconsistencies between previous angular correlations, internal conversion coefficients, and nuclear orientation angular distributions have been satisfactorily resolved by the present results. These data are used to derive a set of $\text{E2}\text{M 1}$ multipole mixing ratios of the transitions between low-lying states. The resulting electromagnetic transition moments are compared with calculations based on the Nilsson model with Coriolis mixing and on the interacting boson-fermion model.     

Inversion of the <Emphasis Type="Italic">K</Emphasis><Superscript>π</Superscript>=1<Superscript>−</Superscript> states in <Superscript>156</Superscript>Gd and <Superscript>170</Superscript>Yb

For the ¹⁵⁶Gd and ¹⁷⁰Yb nuclei, where the inversion of levels in the K^π=1^? bands is observed, the energies of rotational levels are calculated on the basis of the Coriolis interaction model for the states of two bands whose quantum numbers are K^π=1^?. New 0^? levels are introduced in ¹⁷⁰Yb, and the structure of ¹⁷⁰Er is refined. The interaction parameters calculated for six nuclei are considered within the structure predicted by the quasiparticle-phonon model.     

Nuclear orientation study of the decay of 171Lu

The levels and γ-ray transitions in ¹⁷¹Yb have been studied by radioactive decay of oriented ¹⁷¹ Lu. The orientation was produced using the hyperfine field in ferromagnetic gadolinium to polarize an ensemble of ¹⁷¹Lu nuclei at a temperature of 14mK. The directional distribution of the γ-rays was measured using high-resolution Ge(Li) detectors. Anisotropies of 30 γ-rays in ¹⁷¹Yb were measured. Multipole mixing ratios were deduced for most of the mixed γ-ray transitions and unambiguous spin assignments were made for several levels.The energy and structure of the rotational band levels, reduced E2 and M1 transition probabilities and E2/M1 mixing ratios were calculated using the semi-microscopic quasiparticle-phonon model with a Coriolis interaction. In general, good agreement is obtained between the theoretical predictions and experimental results.     

Vibration-rotation Hamiltonian for asymmetric Cs molecules adapted to very strong Coriolis resonance : Application to the microwave reinvestigations of the ν7 and ν9 states of HCOOH and DCOOH

Formic acid is a C_s asymmetric top molecule exhibiting an exceptionally strong Coriolis resonance between its ν₇ and ν₉ vibrational states. The usual molecular model composed of two Watson Hamiltonians coupled by linear and quadratic vibration-rotation coupling terms does not allow satisfactory interpretations of such rotational spectra by microwave spectroscopy. In this case, it is necessary to perform a more complete development of the vibration-rotation coupling part of the standard Hamiltonian operator. The first part of this paper gives details of these developments, yielding a new molecular model adapted to very strong Coriolis resonance for C_s asymmetric top molecules. This new model consists of two Watson Hamiltonians developed up to the sextic centrifugal distortion coefficients and linked by 10 coupling constants. In the second part of this paper, this model has been successfully tested on H¹²COOH and D¹²COOH. From careful microwave reinvestigations of the ν₇ and ν₉ states of these two molecules, numerous new important rotational lines of various μ_b type and intervibrational transitions of μ_c type have been assigned. Various tests are performed to estimate the quality of the results. A critical discussion of the numerical investigation revealed the limits of the new molecular model proposed for strong Coriolis resonance.     

Semi-decoupled bands in the even Hg isotopes

The odd-parity yrast states of the isotopes ^190–200Hg are studied in a model of two quasiparticles coupled to an oblate rotor and interacting by a surface delta interaction. The experimental energy spectra and the enhancement of E2 transition probabilities are well explained by the model. The pure Coriolis coupling problem (i.e., the problem obtained when the residual interaction is suppressed) is investigated in detail. It is shown that the main effect of the Coriolis force is to decouple the high-spin quasiparticle originating in the neutron $\text{1}\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ subshell from the system of the rotor and the low-spin quasiparticle. We study the coupling of a particle to an axially symmetric rotor, which has an intrinsic spin along its symmetry axis, and derive a good approximate solution to the problem.     

Level structure of 47Ti from the (d,p) reaction in 46Ti

The reaction ⁴⁶Ti(d, p) is studied at 10 MeV using the Aldermaston tandem Van de Graaff accelerator and a multichannel magnetic spectrograph. A total of 180 levels are observed up to an excitation of ≈ 7.2 MeV and the stripping angular distributions are analysed in terms of the DWBA theory of direct reactions using the NL/FR optical model potential. Spins, parities and spectroscopic factors are deduced for various levels. Summed spectroscopic factors and quasiparticle energies are obtained for shell model states. Properties of low-lying levels in ⁴⁷Ti are compared with the MBZ and Coriolis coupling models and also with those of the isotonic nuclei ⁴⁵Ca and ⁴⁶Sc.     

Properties of octupole-vibrational bands in the 160Dy nucleus

The mixing of octupole-vibrational bands in the ¹⁶⁰Dy nucleus is analyzed within a phenomenological model that involves Coriolis coupling. The energies of levels in the bands, the reduced probabilities for E1 transitions from the octupole-vibrational bands to the ground-state and γ bands, and the ratios of the reduced probabilities for these transitions to the neighboring levels of the ground-state band are calculated. Satisfactory agreement with available experimental data is reached.     

Coriolis coupling and electromagnetic properties of rotational bands in odd-A Yb nuclei

Influence of a Coriolis coupling on the properties of¹⁷³Yb has been studied using the quasi-particle-phonon model of Soloviev. The energy and structure of the rotational levels, reduced E 2 and M 1 transition probabilities and E 2/M 1 multipole mixing ratios have been calculated. A comparison between theory and experiment is on the whole successful.     

The effects of the microscopical theory of the Coriolis forces on nuclear beta-decay155Eu →155Gd

The wave functions yielded by the microscopical non-adiabatic treatment of the Coriolis interaction proposed in Dubna by Pyatov, Chernej and Baznat have been used in order to calculate the beta decay observables of some allowed transitions of the¹⁵⁵Eu nucleus. The Coriolis interaction effects are important especially for the absoluteft values (an important improvement is obtained) and for theβ-γ circular polarization correlation.