共查询到20条相似文献,搜索用时 46 毫秒
1.
J. Dengler E. König L. F. Larkworthy G. Ritter S. K. Sengupta 《Hyperfine Interactions》1990,56(1-4):1443-1447
The incomplete spin transition between the low-spin (LS) (S=1/2) and the intermediate-spin (IS) (S=3/2) states in the iron (III) complex Fe(J-mph)NO (mph=4-methyl-o-phenylene), centered atT c≈212 K, has been studied with57Fe Mössbauer spectroscopy and magnetic susceptibility measurements between 80 K and 320 K. The lineshape of the Mössbauer spectra is well reproduced by a two state stochastic relaxation model resulting in values of about 2·106 s?1 to 7·106 s?1 for the IS→LS transition rate constantk IL. The kinetics of this spin transition can be described by an Arrhenius equation yielding activation energiesE IL=1.1 (2) kJ/mol andE LI=6.1 (2) kJ/mol for the IS→LS and LS→IS conversion, respectively. 相似文献
2.
S. Hörbäck Ann -Marie Pendrill Leslie Pendrill M. Pettersson 《Zeitschrift für Physik A Hadrons and Nuclei》1984,318(3):285-290
Doppler-free two-photon laser spectroscopic measurements in the deep red spectral region have been performed on the transition 42 S 1/2→42 D J in the naturally abundant isotopes 39 and 41 of atomic potassium. The 4D level isotope shift, ?81±12 MHz was obtained by combining the current results with data from Rydberg-state spectroscopy. Many-body perturbation theoretical calculations of the specific mass shift in the measured state are also presented. With the use of Brueckner orbitals the value ?70 MHz was obtained in substantial agreement with the experimental result. 相似文献
3.
Impact broadening and shifts of Ba transitions to parity forbidden Rydberg states have been measured using two-photon laser spectroscopy techniques. Broadening and shift rates for the 6sns 1S0 (10 < n < 19) and 6snd 1D2 (8 < n < 26) levels due to thermal collisional interactions with Xe, Kr and Ar as perturber gases are plotted. Perturbations due to configuration interactions are discussed. 相似文献
4.
U. Krönert St. Becker G. Bollen M. Gerber Th. Hilberath H. -J. Kluge G. Passler ISOLDE Collaboration 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(4):521-522
Resonance ionization mass spectroscopy (RIMS) and pulsed-laser induced desorption (PLID) have been combined in order to study the isotope shift (IS) and hyperfine structure (HFS) of184Au (T1/2=53 s) and183Au (T1/2=42 s) in the 6s2S1/2 → 6p2P1/2 (λ=267 nm) transition. The Au isotopes were obtained as daughters in the decay of184,183Hg produced and mass separated at the new ISOLDE-3 facility at CERN. It was found that the strong deformationβ 2}-0.25 setting in at186Au persists down to183Au. 相似文献
5.
Two-photon laser spectra of the Yb vapor have been obtained. Transitions to highly excited 4f14 6sns1S0 and 4f14 6snd 1D2 states are seen in direct two-photon excitation. Hybrid resonances involving 4f14 6s6p 1P01 and 4f14 5d6s 3D2 intermediate states lead to transitions to 4f14 6sns1S0, 4f14 6snp 3P02,1 and 4f14 6snd 1D2 levels. 相似文献
6.
S. G. Zemlyanoi D. V. Karaivanov Yu. P. Gangrsky K. P. Marinova B. N. Markov J. Badamsambuu 《Hyperfine Interactions》2010,196(1-3):107-113
Using the method of laser-induced fluorescence in an atomic beam we have measured the hyperfine splitting constants, A and B, of the ground and excited states of the optical transition 4f 76s 2 8S $_{1/2}\to 4f^{7}$ 6s6p 6P5/2 (564.58 nm) for 151???155Eu isotopes. For all isotopes, the magnetic dipole constants of the 6P5/2 atomic level are determined to a precision better than 0.04%. The A and B constants for the ground state 8S7/2 of the radioactive 152,154,155Eu were obtained for the first time with a precision better than 0.5%. Our data along with previous ground state hyperfine structure measurements for the stable europium isotopes allow us to determine the hyperfine anomaly for mentioned Eu isotopes. 相似文献
7.
High-resolution laser-atomic-beam spectroscopy has been used to determine isotope shifts in five transitions between low-lying states of Sr I. With these results and existing data a parametric analysis of level isotope shifts has been performed. The transition isotope shifts have been separated into field shift and mass shift contributions with a King-plot procedure using model-independent nuclear charge equivalent radiiR k from muonic x-ray measurements. Values for the mean-square nuclear charge radiiδ〈r 2 〉 have been calculated from the field shifts in the optical transitions 5s 2 1 S 0-5s5p 3 P 1 and 5s5p 3 P 0-5s6s 3 S 1 and compared with correspondingδ〈r 2 〉 values evaluated from muonic x-ray data. 相似文献
8.
The Doppler-free two-photon absorption method performed with a narrowbandc w dye laser permitted high resolution measurements of transitions from the Ba I ground state 6s 2 1 S 0 to several highly excited states. The lifetimes and hyperfine splittings of these states as well as the isotope shifts of the transitions have been determined accurately. The lifetime values are in agreement with transition probability data; the hyperfine splitting results show considerable configuration interaction effects. A detailed discussion of the isotope shifts is given. 相似文献
9.
Very accurate measurements of then 2 S 1/2 (n=9–30),n 2 P 1/2,3/2 (n=9–50) andn 2 D 3/2, 5/2 (n=5, 8–32) energy levels in Cs I have been performed in the wavelength-range 6,379 Å<λ<7,432 Å with a high-precision vacuum-wavemeter using either Doppler-free two-photon spectroscopy or Doppler-limited one-photon spectroscopy with a frequency-doubling crystal. Thermionic detectors were used throughout the experiments. By fitting the experimental energy values to extended Rydberg-Ritz formulas, accurate quantum defect data and series limits are given. The ionization energyE i =31,406.4710(7) cm?1 was adopted to be the best fit value, differing significantly from most recent evaluations of other authors, but agreeing well with former, less accurate measurements performed in our laboratory. 相似文献
10.
Penning electron distributions arising from the ionization of Na and K by He (1s 2s 1,3 S)-metastables in thermal collisions, as well as the absolute cross section for Penning ionization of Na by He (23 S) and relative cross sections for ionization of Na and K by He(21 S) and He(23 S) are measured. It is shown that under fairly general conditions the well depth ε* of the interaction potential between the metastable and the target particle can be obtained directly from the measured electron distributions. ε*-values are reported for the moleules He(1s 2s 1,3 S)-Na(2 S), K(2 S) (2,2Ω), and for He(1s 2s 1,3 S)-Hg(1 S)(1,3Ω). These latter values are obtained from previously published measurements and are to be considered preliminary. Further, additional evidence is given, that Penning ionization with metastables is an electron exchange process. 相似文献
11.
Two efficient and isotope-selective resonant two-photon ionization techniques for loading barium ions into radio-frequency (RF)-traps are demonstrated. The scheme of using the strong dipole-allowed transition 6s 2? 1S0→6s6p? 1P1 at λ=553 nm as a first step towards ionization is compared to the established technique of using a weak inter-combination line (6s 2? 1S0→5d6p? 3D1,λ=413 nm). An increase of two orders of magnitude in the ionization efficiency is found favoring the transition at 553 nm. This technique can be implemented using commercial all-solid-state laser systems and is expected to be advantageous compared to other narrowband photo-ionization schemes of barium in cases where highest efficiency and isotope-selectivity are required. 相似文献
12.
Hartmuth Arenhövel 《Zeitschrift für Physik A Hadrons and Nuclei》1981,300(1):25-30
The hyperfine structure (hfs) splittings of the metastable 1s2s 3 S 1 state of7Li+ have been measured with combined laser optical pumping and microwave resonance. A lowenergy Li+ ion beam, optically excited by an intersecting laser beam, passed a waveguide where radio frequency transitions were induced. The resulting population transfer among the hfs levels of the3 S 1 was detected via the change in intensity of the fluorescence light from a second crossing region of laser light and ion beam located past the waveguide. The magnetic hfs constantA(7Li+, 1s2s 3S1) was measured and compared with theory. A deviation of the two transition frequenciesν(F=3/2?F=5/2) andν(F=1/2?F=3/2) from the interval rule is due to a depression of theF=3/2 hfs sublevel, caused by mixing of the 23 S 1 and 21 S 0 states via hyperfine interaction. This shift was never observed so far in a two-electron spectrum, because of absence ofI>1/2 isotopes in He, the only two-electron atom investigated spectroscopically with high precision. The size of the shift is in fair agreement with a theoretical estimate. 相似文献
13.
The impact broadening of strontium 5sns 1 S 0, 5snd 1 D 2 and 5snd 3 D 2 levels by He and Xe have been studied by measuring the collisional half-widths of Doppler-free two-photon absorption lines from the 5s 2 1 S 0 ground state in a thermionic diode. Large inelastic contributions to the broadening rates of the levels have been found where the moduli of the quantum defects of different level series are close to each other. A similar but continuousn-mixing behaviour along the series has also been found in our recent investigation on the broadening of Rb levels by noble gases. The broadening rates of the very high levels in Sr were found to be independent on the principal quantum number and the angular momentum of the levels and in good agreement with our recent broadening data of the Rb-He and Rb-Xe systems and the data for Na-He and Na-Xe found by the Columbia group. 相似文献
14.
P. Villwock S. Siol Th. Walther 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(1-2):251-255
We report on the cooling of neutral mercury in a magneto-optical trap utilizing the spin forbidden 1S0 → 3P1 transition at 253.7 nm. We trapped two Hg isotopes, i.e. the bosonic 202Hg and the fermionic 199Hg isotope, respectively. The temperature of the cold atom cloud was determined to be approximately 300 μK using a modified TOF-method. It is currently limited by the quality of the laser lock. Trapped neutral Hg has many interesting avenues such as a time standard and high precision measurements. Here, we discuss the possibilities of photo-association spectroscopy and the generation of ultra-cold Hg2 dimers. 相似文献
15.
V. N. Knyukshto E. I. Sagun A. M. Shul’ga S. M. Bachilo É. I. Zen’kevich 《Optics and Spectroscopy》2000,88(2):205-216
It is shown that steric interactions of volume substituents in the β-positions of pyrrole rings and the nitro group in mono-and di-meso-phenyl-substituted of octaethylporphyrins and their chemical dimers containing the electron-acceptor NO2 group in the ortho-position of the phenyl ring at 295 K favor the direct overlap of molecular orbitals of the interacting subunits, resulting in the efficient quenching of fluorescence due to the direct electron transfer from the S1 level to the lower-lying state via the “through-space” mechanism. The electron transfer in these compounds in nonpolar media (the rate constant k et S =(3.2–9.5)×109 s?1 is nonadiabatic, whereas in strongly polar solvents (k et S =2×1011 s?1) the adiabatic effects can be manifested. In compounds containing the NO2 group in meta-or para-positions of the phenyl ring, the nonadiabatic electron transfer from the S 1 level occurs less efficiently both in polar [k et S =(0.2–5)×1010 s?1] and nonpolar media [k et S =(0.1–1.0)×107 s?1]. In this case, the electron transfer involves molecular orbitals of phenyl (the “through-bond” mechanism), and its efficiency depends on the orbital electron density in the meta-and para-positions of the phenyl ring. Based on the experimental data obtained and analysis of the electron transfer within the framework of the Marcus theory, the energy scheme of relaxation processes of the electronic energy in the compounds under study involving charge transfer states is suggested. 相似文献
16.
H. Myint R.M. Hill W.R. Hindmarsh 《Journal of Quantitative Spectroscopy & Radiative Transfer》1979,22(5):489-497
The Lorentzian half-widths of the Ca λ4227 Å (4s21S0?4s4p1P1) line in the impact regime have been measured by low resolution spectroscopy. They were determined from measurements of the total absorption of both a white source and an emission line of the same transition. The absorption cells contained calcium at about 410°C with a perturbing gas of argon at pressures of up to about 50 cm of Hg. Corrections were applied to account for the width of the emission line and the non-transparency of the absorption cells. High resolution measurements of absorption profiles from a grating spectrometer are also described and the results of both methods are compared. 相似文献
17.
H.P. von Arb F. Dittus H. Heeb H. Hofer F. Kottmann S. Niggli R. Schaeren D. Taqqu J. Unternährer P. Egelhof 《Physics letters. [Part B]》1984,136(4):232-236
The lifetime of the 2S state in (μ?4He)+ ions has been measured at He-gas pressures between 50 Torr and 6 atm (T=300 K). We observed both X-rays from the two-photon 2S→1S transitions as well as delayed Kα X-rays associated with radiative quenching. The quenching rate is strongly pressure dependent; it is predominantly a quadratic function of pressure with a measured three-body rate coefficient k=(5.9±0.8)×10?32cm6/s. At 6 atm, we find τ2S<250 ns because of the absence of two-photon transitions. 相似文献
18.
Exact quantum-electrodynamic calculations of the interelectron interaction corrections are performed for the 1s 1/22s 1/2 1 S 0, 1s 1/22p 1/2 3 P 0, and 1s 1/22s 1/2 3 S 1 configurations in He-like ions and for the (1s 1/2)22s 1/2 and (1s 1/2)22p 1/2 configurations in Li-like ions for all charges of nuclei 10≤Z≤92. The calculations are performed in the Coulomb calibration. The Coulomb-Coulomb and the Coulomb-Breit parts are calculated exactly, and the Breit-Breit part of the correction is calculated by neglecting the retardation. The calculations are the most exact of those available by now. 相似文献
19.
U. Klingbeil J. Kowalski F. Träger H. -B. Wiegemann G. zu Putlitz 《Zeitschrift für Physik A Hadrons and Nuclei》1979,290(2):143-148
The isotope shift40Ca-43Ca in the 4s 2 1 S 0-4s4p 3 P 1 intercombination line as well as the hyperfine structure splitting of the 4s4p 3 P 1 state of43Ca have been remeasured by saturation spectroscopy with a tunable stabilizedcw dye laser and an atomic beam of natural Ca as absorber. The nuclear charge radius of43Ca obtained here reconciles our result with the radius obtained from measurements in muonic Ca-atoms and in the Ca resonance line. It reconfirms the fact that the charge radius of43Ca is considerably smaller than the ones of both neighbouring even isotopes. The discrepancy of our previous measurement for this charge radius was due to a wrong assignment of so far unobserved absorption lines of probably molecular origin occuring in the neighbourhood of the atomic resonances under study. 相似文献
20.
E. V. Gryzlova A. I. Magunov S. I. Strakhova 《Bulletin of the Lebedev Physics Institute》2010,37(12):381-385
The effect of the resonant structure in the continuous spectrum induced by an external laser field due to the coupling of continuum states with the 1s4s 1 S level in helium on cross sections of elastic and inelastic scattering of probe radiation on an atom in the metastable 1s2s 1 S state at an energy above the ionization threshold is theoretically studied. Explicit expressions for the angular distribution and the degree of polarization of scattered photons as functions of probe and laser radiation characteristics are derived in the rotating wave approximation. Frequency, angular, and polarization dependences of the cross sections of scattering into final 1s 2 1 S, 1 s2s 1 S, and 1s4s 1 S atomic states are calculated. 相似文献