Lifetime measurements of some levels belonging to the 3p <Emphasis Type="Bold">5</Emphasis>nd ( , 5, 6, 7) configuration of ArI

Lifetimes of some 3p^5nd (n = 4, 5, 6, 7) levels of neutral argon have been measured by high frequency deflection technique with a delayed coincidence single photon counting arrangement. The measurements have been performed under conditions where pressure dependent effects are negligible. Lifetimes of some of the levels have been measured for the first time. The results have been compared with other experimental and theoretical values. Received 7 August 2002 / Received in final form 20 December 2002 Published online 24 April 2003     

Pulsed jet rotational spectra of the propylene oxide-neon molecular adduct

Rotational transitions of the propylene oxide-²⁰Ne and propylene oxide-²²Ne molecular adducts have been measured, in the frequency region from 4 to 18 GHz, using a pulsed jet Fourier Transform microwave spectrometer. The transition frequencies were used to refine the rotational and distortion spectroscopic constants obtained from the previous free jet millimetre wave measurements of the complex. No splittings due to the methyl group internal rotation were detected.     

Lifetime measurement of some excited states belonging to the 3p<Superscript>4</Superscript>nd (n=4–6) configuration of ArII

The radiative lifetimes of eight levels belonging to the 3p⁴nd (n=4–6) configuration of ArII have been measured using high frequency deflection technique together with a delayed coincidence single photon counting arrangement. Lifetimes of some of the levels have been measured for the first time. The results have been compared with other experimental and theoretical values.      

Experimental lifetime of some level belonging to the 5p46d configuration of XeII

Lifetimes of eight levels belonging to the 5p⁴6d configuration of singly ionized xenon have been measured by high frequency deflection technique with a delayed coincidence single photon counting arrangement. The results have been compared with other experimental and theoretical values. The lifetimes of the 6d ²F_3/2 and 6d ⁴F_3/2 levels have been measured for the first time.     

Lifetimes of rotational levels in170W

Lifetimes of the first 2⁺, 4⁺ and 6⁺ levels in¹⁷⁰W have been measured by the recoil-distance method based on the Doppler effect, using the¹⁵⁵Gd (²⁰Ne, 5n)¹⁷⁰W reaction. The following conclusions can be drawn from the results: if there are any deviations from the predictions of the rotational model for the lifetimes of the 4⁺ and 6⁺ states, they are smaller than 8.5 %; if this model accurately describes the nucleus¹⁷⁰W, the intrinsic quadrupole moment of this nucleus is: Q₀=5.93±0.06 barns, and its deformation is: β=0.240±0.003. The value of Q₀ is compared with the predictions of various calculations for the tungsten isotopes.     

Lifetime measurements in 56Co

Lifetimes of six excited states in ⁵⁶Co below 1.75 MeV have been measured by the Doppler-shift attenuation method. The levels were excited via the ⁵⁴Fe(³He, pγ) reaction with 10.4 MeV ³He particles. Gamma rays were measured in a 45 cm³ Ge(Li) detector in coincidence with protons backscattered near 180°. Reduced transition probabilities extracted from measured lifetimes compare favourably with shell model predictions of McGrory.     

Contact density and number of 5s electrons inβ-Sn

Lifetimes and feeding times of high spin states in ¹⁵⁶ Er have been measured employing the recoil distance method in the reaction ¹²³ Sb(³⁷ Cl,4n) at bombarding energies of 158 and 166 MeV. The yrast states up to spin 20 ? were found to be collective. These levels are fed, however, from long-lived high spin states, causing time delays up to ～ 100 ps, the existence of which is interpreted as a signature for an oblate shape at high spin.     

Atomic states of lithium by the beam-foil technique in the spectral range 400–1900 Å

⁶Li⁺-ions accelerated electrostatically to energies of 200–390 keV are electronically excited by the beam-foil technique. The emitted light is analyzed with a Seya-Namioka VUV monochromator in the wavelength range 400–1900 å. All Li II and Li III lines known from theory — in one case emitted by an=9 level — are detected, several of them for the first time. Lifetimes of 20 Li II levels, some not measured previously, are determined after correction for cascades. The accuracy of the experimental values for several lifetimes is better than that of theoretical predictions.     

Measurements and Hauser-Feshbach analysis of the10B(16O,6Li)20Ne reaction

States in²⁰Ne were populated by the¹⁰B(¹⁶O,⁶Li) reaction, and levels were observed up to 11 MeV in excitation energy. Cross sections were measured at 7° (lab) for bombarding energies from 44.4 to 46 MeV in 400 keV intervals. The reaction appears to be predominantly due to compound nucleus formation, and good agreement was found between the measured cross sections and Hauser-Feshbach calculations, assuming the known spin values of²⁰Ne.     

Lifetimes of (2p53s1,3P) levels of Na II

Lifetimes of the resonance levels (2p⁵3s^1,3P) of Na II have been measured by the beam-foil method. The experimental accuracy is better than that of available theoretical predictions.     

Investigation of22Na excited states

Fourteen²¹Ne(p, γ)²²Na resonances have been observed in the rangeE _p =300–1,300 keV. Theγ-decay of all these resonances has been investigated by means of a 38 cm³ Ge(Li) detector. Energies and branching ratios of several bound states have been determined. TheQ-value was determined as 6,738.5±1.7 keV. Lifetimes of seven states were determined with the Doppler-shift attenuation method. The observed upper limit (τ _m ≦4 fs) of the lifetime for the 4,071 keV state, regarded as the analogue of the third excited state in²²Ne, and the transition observed from this state to the 1,528 keV state do not support the proposed rotational band structure of the²²Na low-lying states.     

Spektroskopische Untersuchung unelastischer Stöße zwischen Ionen oder metastabilen Atomen der Edelgase und Alkalimetallatomen bei thermischen Stoßenergien

The present work deals with the spectroscopic investigation of Penning ionization and nonresonant charge exchange due to thermal-energy collisions of metastable atoms or ions of the inert gases He, Ne with atoms of alkali metals K, Rb, Cs in a low temperature plasma of the corresponding binary mixtures. The rate constants of these reactions and partial rate constants of exciting several alkali metal ion levels were determined by the kinetics of the decay of ionized and excited particles in the afterglow of a pulsed discharge. Measured Penning and charge exchange constants are in order of 10^10-9 cm³ sec^?1. Partial Penning constants in the He? Cs system exhibit a small dependence of the energy defect of reaction, whereby an important part of collisions results in excited Cs⁺-states. On the contrary, energy transfer by charge exchange in He? Rb, Cs systems distinguishes by a significant energy defect dependence. Charge exchange from He⁺ to Rb₀ leads above all to He(2³S₁)-atoms and normal Rb⁺-ions. It follows from the metal ion spectrums, that Penning ionization and charge exchange of the investigated systems under utilized conditions represent as processes of selective excitation of alkali metal ions in afterglow and stationary discharge.     

Transition probabilities in the Ni-Zn region

Lifetimes of low-lying nuclear levels of^61,63Ni,^60,62Cu,^63,65,67Zn and^65,66Ga have been measured by means of the delayed coincidence technique. A comparison of the results with available theoretical predictions is given. Properties of low-lying levels of odd Ni- and odd Zn-isotopes are compared.     

Lifetimes of levels in 25Na and 26, 27Mg excited via the 26Mg bombardment of 3H

Lifetimes have been measured for nine levels in ²⁵Na, the first two excited states of ²⁷Mg, and the First excited state of ²⁶Mg by bombarding a Ti³H target with 40 MeV ²⁶Mg ions. Mean lifetimes were determined by fitting the Doppler-broadened γ-ray lineshapes with lineshapes calculated using experimentally-measured stopping powers. The ²⁵Na results are compared to predictions of recent shell-model calculations.     

Vibrational relaxation of KrF* and XeCl* by rare gases

A steady-state, chemiluminescence technique has been used to measure effective rate constants for vibrational relaxation as a function of vibrational level for KrF^* in collisions with He, Ne, and Ar and XeCl^* with Ar. The effective rate constants reported include contributions to relaxation due to intersystem crossing between theB andC states, in addition to direct relaxation within theB state. The relevance of these results to the understanding of previous measurements in KrF and XeCl lasers is discussed.     

Experimental and theoretical lifetimes in Yb III

Lifetimes of three levels belonging to the configuration 4f ¹³5d with J = 1 in Yb III have been measured for the first time using the time-resolved laser-induced fluorescence method. Experimental transition probabilities have been deduced for the transitions between the levels studied and the ground state. The comparison of the experimental lifetimes with theoretical data, deduced within the relativistic Hartree-Fock (HFR) approach, underlines the dramatic importance of an adequate consideration of core-polarization effects in the theoretical model and the sensitivity of one of the lifetime values to small correlation effects. Received 2 April 2001     

Hyperfine structure in 21Ne using laser-induced absorption line narrowing

Using Absorption Line Narrowing (A.L.N.) in three-level atomic systems in interaction with two quasi-resonant single-mode laser, we have measured the magnetic and eletric hyperfine constants of the 1s₄, 1s₅, 2s₂ and 2p₄ levels of ²¹Ne.     

Lifetimes of high-spin yrast states in 154Er

Lifetimes for high-spin levels (between about 10 and 30 ?) in ¹⁵⁴Er have been measured by the recoil-distance method. Non-collective, moderately collective and collective E2 transitions from states with lifetimes between at most 10 and 400 ps have been found. All available data on this nucleus are discussed within the framework of the oblate coupling scheme with the addition of collective degrees of freedom.     

Lifetimes in73Se

Lifetimes of 8 levels in⁷³Se have been measured by the recoil distance Doppler shift technique via the reaction⁶⁰Ni(¹⁶O, 2pn)⁷³Se. Energies of negative and positive parity states as well asE 2 transition strengths are compared with theoretical values obtained from a symmetric rotor plus particle model and a triaxial rotor model.     

γ-Spectroscopy of 89 215 Ac126 and proton pairing inN=126 isotones

Theγ-decay of 5 excited states along the yrast line has been observed in²¹⁵Ac by inbeamγ-spectroscopy. Lifetimes andg-factors of 3 isomeric levels have been measured. The data show that pairing dominates the structure ofN=126 isotones.