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1.
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   

2.
Pressure shifts of the 3snd 1D2 Rydberg states to n = 23 have been measured for He, A and Xe and found to agree with previous results for 2P states of alkalis. Improved term values for the energy levels from n = 13 to 23 have been obtained.  相似文献   

3.
More than two thousand Stark resonances of the ν4 and 2ν2 band transitions of 14NH3 and 15NH3 were observed at Doppler-limited resolution with a CO laser. Fourier transform infrared spectroscopy on 15NH3 is also carried out. Thirty-six new microwave transitions including seven perturbation-enhanced transitions are observed in the v4 = 1 excited vibrational state of 14NH3 and 15NH3. Accuracies of all available spectroscopic data on the v4 = 1 and the v2 = 2 states are evaluated and analyses of the vibration-rotation spectra are performed. The Coriolis interaction between the closely lying v4 = 1 a (antisymmetric level) and v2 = 2 s (symmetric level) states is explicitly included in the analysis. Smaller Coriolis interactions between the v4 = 1 a and the v2 = 1 s states and between the v2 = 2 s and the v2 = v4 = 1 a states (i.e., (v1, v2, v3, v4) = (0 1 00 11)) are also taken into consideration. The accuracy in determination of the principal molecular constants is 10?6. The parameters thus obtained reproduce the frequencies of the vibration-rotation transitions and inversion transitions within the accuracy of 0.0024 cm?1.  相似文献   

4.
The optical excitation functions (OEFs) for four series of spectral lines of the Zn atom at the transitions 4sn 1 s 1 S 0 → 4s4p 1 P 1 (n 1 = 6–10), 4sn 2 s 3 S 1 → 4s4p 3 P 2 (n 2 = 6−8), 4sn 3 d 1 D 2 → 4s4p 1 P 1 (n 3 = 4−6), 4sn 4 d 3 D 1, 2, 3 → 4s4p 3 P 2 (n 4 = 4−7) excited by a monoenergetic (0.04–0.08 eV) electron beam with energies from the excitation threshold to 18–19 eV are measured. In the energy dependences of the excitation cross sections, the effect of post-collision interaction of slow (scattered) and fast (emitted after the autoionization state decay) electrons is observed and described. This interaction leads to the capture of a slow electron into the listed discrete levels and the appearance of maxima in the excitation functions. The energies of the maxima are used to determine the energies and widths of single autoionization states or their groups by approximate formulas of the classical approach. The autoionization levels of the zinc atom responsible for the maxima observed are determined. Possible transfer of the orbital angular momentum between electrons is analyzed.  相似文献   

5.
Angular distributions of tritons from the 6Li(n, t)4He reaction were measured at En = 7.25, 6.77, 6.57, 5.24 and 4.71 MeV. Angular distributions of douterons from respectively, the 6Li(n, d)5He two-body breakup reaction were measured at En = 6.77 and 6.57 MeV, and of protons from the 6Li(n, p)6He reaction at En = 6.77, 5.24 and 4.71 MeV. All these reactions in 6Li were analyzed as direct interaction in the formalism of the distorted wave Born approximation. The optical model for the nuclear interaction was found to apply reasonably well to nuclei as light as 4He, 5He, 6He and 6Li. In addition, 6Li as an alpha-deuteron cluster gives the best bound-state wave function to describe the experimental angular distribution of tritons. The excitation functions at forward angles of the 6Li(n, t)4He, 6Li(n, d)5He and 6Li(n, p)6He reactions were measured for incident neutron energies between 4.4 and 7.3 MeV. It is found that the 6Li(n, d)5He two-body breakup reaction has a threshold at about En = 5.3 MeV. Angular distributions at En = 18.3 MeV for tritons and protons from the 9Be(n, t)7Li and 9Be(n, p)9Li, respectively, were also measured.  相似文献   

6.
For nucleons interacting via formation of the quark compound bag the resulting potential is written in a general form. Explicit examples of potentials are constructed in the 1S0, 3S1 and 3S1-3D1 states fitted to the experimental data at TL ? 1 GeV. As an outcome the QCB energy levels (dibaryons) and NN admixture in QCB are obtained in good agreement with theoretical predictions.  相似文献   

7.
The ν2 + ν3 bands of 12CH4 and 13CH4 occurring in the region 4400–4650 cm?1 have been studied from spectra recorded with a high-resolution Fourier transform spectrometer (resolution better than 0.01 cm?1). Champion's Hamiltonian expansion, Canad. J. Phys.55, 1802 (1977), is applied to the problem of the two interacting F1 and F2 vibrational sublevels of this type of a band. As the P branch of ν2 + ν3 is strongly overlapped by neighboring bands, a combination-difference method, adapted to tetrahedral XY4 molecules has been developed to help assignments of lines. A fit of 700 transitions has been performed using 13 new effective constants in the case of 12CH4. In the case of 13CH4, 532 transitions have been fit to 18 constants. The known parameters, relative to the vibrational ground state and the ν3 state for both methanes, and the ν2 state for 12CH4 were fixed throughout. Most of the perturbed levels, up to J′ = 12, are well reproduced and the general agreement between experimental and calculated transitions is satisfactory with standard deviations of 0.047 cm?1 (12CH4) and 0.041 cm?1 (13CH4). The results (order of magnitude of obtained (ν2 + ν3) parameters and comparison of observed and computed intensities) indicate that the ν2 + ν3 band is perturbed by many other bands.  相似文献   

8.
The Fourier transform spectra and the diode laser spectra of the ν2 band of 14NH3 have been measured with 0.005 and 0.002 cm?1 resolution, respectively. A simultaneous least squares analysis has been carried out of these data together with the microwave, submillimeterwave, diode-laser heterodyne, and infrared-microwave two-photon transition frequencies between the ground and the ν2 inversion-rotation levels. A theory of the Δk = ±3n interactions in the ground and ν2 excited states of ammonia (?. Urban, V. ?pirko, D. Papou?ek, J. Kauppinen, S.P. Belov, L. I. Gershtein, and A. F. Krupnov, J. Mol. Spectrosc.84, 288–304 (1981)) has been used in the analysis. The “smoothed” values of the ν2 band wavenumbers can be used for calibration purposes with better than 1 × 10?4 cm?1 precision. On the basis of these results, a critical evaluation has been carried out of several experimental techniques of very high resolution infrared spectroscopy.  相似文献   

9.
We have performed 169Tm and 161Dy Mössbauer spectroscopy on TmFe4Al8 and DyFe4Al8. From the temperature dependence of the electric quadrupole splitting of the 169Tm spectra of TmFe4Al8 we have determined the second order crystal field potential V02 = (100 ± 10) K and the exchange field term gJμBHM = (1 ± 1) K. The temperature dependence of the hyperfine field of the 161Dy spectrum of DyFe4Al8 gives gJμBHM = (15 ± 3) K. With these exchange fields magnetic transition temperatures of the rare earth sublattices were found, which are consistent with experiment. The relaxation behaviour of the Tm sublattice below TN = 187 K is discussed.  相似文献   

10.
The CuPL defect is characterized by intense photoluminescence (PL) emission with a 1014 meV zero-phonon line and has since long been called the ‘copper-pair’ defect. However, recent PL studies in isotopically pure 28Si samples show clear evidence for four Cu atoms in this defect. This defect is one of a family of complexes that contain four (sometimes five) metal impurities. No complex containing two or three metal impurities (at least one of which is a transition metal) has been reported. We have performed systematic calculations of a priori possible Cu4 complexes, including the Cus1Cui3 complex proposed by Shirai et al. [18]. This complex has the lowest formation energy of all the Cu4 defects. We have studied its properties using first-principle theory. In addition to the structures, binding energies, and vibrational spectra, we studied the formation pathway in an attempt to figure out why smaller (or larger) complexes do not form. We find that Cus1Cuin with n=0, 1 or 2 continue to trap Cui+ if the Fermi level is midgap, and that the process stops when n=3. © 2011 Elsevier Science. All rights reserved  相似文献   

11.
A new optogalvanic technique with an rf discharge was applied to a high-resolution study of the Rydberg states of N2. The Ledbetter band, c4(0)1Πua″(0)1Σg+, and a new visible band, c5(0)1Σu+a″(0)1Σg+, were studied at a Doppler-limited resolution of 0.05 cm?1. A Doppler-free method was also applied to resolve overlapped lines. Precise wavenumbers were determined for the rotational transitions of the two Rydberg bands. The rotational and the centrifugal constants for the lowest Rydberg state, a″(0)1Σg+, were determined to be B0 = 1.913748(42) cm?1 and D0 = 6.088(99) × 10?6 cm?1, where the numbers in parentheses are the standard deviation and apply to the last digits.  相似文献   

12.
Line strengths and self- and nitrogen-broadened half-widths were measured for spectral lines in the ν3 and ν2 + ν4 bands of 12CH4 and 13CH4 from 2870–2883 cm?1 using a tunable diode laser spectrometer. From measurements made over a temperature range from 215 to 297 K, on samples of 12CH4 broadened with N2, we deduced that the average temperature coefficients n, defined as bL0(T) = bL0(T0)(TT0)?n, of the Lorentz broadening coefficients for the ν3 and ν2 + ν4 bands of 12CH4 were 0.97 ± 0.03 and 0.89 ± 0.04, respectively. A smaller increase is observed in line half-width with increasing pressure for E-species lines, for both self- and nitrogen-broadening, than for other symmetry species lines over the range of pressures measured, 70 to 100 Torr.  相似文献   

13.
Hysteresis has been observed at the cooperative high-spin (5T2) ? low-spin (1A1) transition in Fe (4, 7-(CH3)2-phen)2(NCS)2 where phen = 1, 10-phenanthroline. The transition is centered on Tc> = 121.7 K for rising and on Tc< = 118.6 K for lowering of temperature. The observations are in only qualitative agreement with the thermodynamic theory of Slichter and Drickamer.  相似文献   

14.
Doppler-limited, laser-induced fluorescence spectra on the B1Σ+-X1Σ+ (v′ = v″ = 0 and 1) system of MgO have been obtained. The results of the optical analysis were merged with our microwave-optical double-resonance measurements to produce the following set of spectroscopic parameters for the B and X states, where the units are in cm?1, and the uncertainties represent 95% confidence limits: T0.0 = 20003.594(2); B0 = 0.58004(3); D0 = 1.13(2) × 10?6; B0 = 0.57198(3); D0 = 1.20(2) × 106; T1.1 = 20043.423(2); B1 = 0.57528(4); D1 = 1.14(11) × 106; B1 = 0.56674(4); D1 = 1.22(10) × 106.  相似文献   

15.
Large numbers of ‘hot’ bands in the first electronic absorption systems of 12CS2 and 13CS2 have been analyzed from plates taken at high dispersion, and accurate rotational constants have been obtained for the overtones of the ground state bending vibration up to v2 = 6 and l = 3 for 12CS2 and v2 = 4, l = 2 for 13CS2. The energy differences between the various levels with the same l value have been determined to an accuracy of about ±0.006 cm?1, but (because of the parallel polarization of the electronic transition) the absolute energies of levels with l > 0 cannot be obtained.  相似文献   

16.
Relative and absolute line intensities for the ν3 bands of the 12C and 13C isotopic varieties of methane have been measured using a tunable difference-frequency laser spectrometer. From these data the integrated band strength of 13CH4 is calculated to be 0.983 ± 0.007 that of 12CH4, with the uncertainty representing three standard deviations. The absolute ν3 bandstrength for 12CH4 is 266.1 ± 3.0 cm?2 atm ?1 at 294.7 K where the errors are dominated by the pressure measurement. This band strength corresponds to an effective transition moment 〈μ3〉 = 0.0534(3)D for 12CH4 from which the ν4 band dipole moment and the Herman-Wallis F factor can be estimated using a recent force field model for methane.  相似文献   

17.
The frequencies and assignments of 50 lines in the pure inversion spectrum of 14NH3 in the 00011 vibrational state are reported in the microwave frequency region 18–53 GHz and in selected regions up to 58 GHz.The J = 0 inversion frequency, K-type doubling constant K, l = 2, ?1 and molecular dipole moment in this state are 32 904.7 ± 2.0 MHz, 1.958 ± 0.040 MHz and 1.459 ± 0.002 D, respectively, where model inadequacies are included in the uncertainties of the first two parameters. The dipole moment measurements for this and the ground state are in excellent agreement with Stark laser measurements. An expression containing the effective l-type doubling constant is obtained from the combination of frequencies [ν(1, 1, 1) ? ν(1, 1, ?1) ? ν(2, 1, 1) + ν(2, 1, ?1)]8 = 10 361.894 ± 0.004 MHz. A preliminary value for the l-type doubling constant is 10 655 ± 20 MHz.  相似文献   

18.
Distinct and different X-ray diffraction patterns are found for the 5T2 and 1A1 phases at the high-spin(5T2) ? low-spin(1A1) transition in Fe(bt)2(NCS)2 (I) and Fe(phy)2(ClO4)2 (II) (bt = 2,2′-bi-2-thiazoline; phy = 1,10-phenanthroline-2-carbaldehydephenylhydrazone). The peak profiles show the same temperature dependence and the same hysteresis behaviour as the 5T2 and 1A1 fractions determined on the basis of Mössbauer effect or magnetism. At the transition temperature Tc, both phases are coexistent.  相似文献   

19.
Measurements of the line strengths of the (1110,0310)II-0000 band of CO2 (1932.466 cm?1) have been made with high resolution. They exhibit a strong Coriolis interaction which enhances the P-branch intensity while reducing that of the R branch. The rotationless dipole moment of the transition and the ξ-constant representing this interaction have been determined as: R(0) = (6.57 ± 0.03) × 10?4D, ξ = ?0.0598 ± 0.0002.  相似文献   

20.
The so-called pentad of 12CD4 consists of the vibrational states v1 = 1(symmetry A1), v3 = 1(F2), v2 = 2(A1 + E), v2 = v4 = 1(F1 + F2), and v4 = 2(A1 + E + F2). All states are located in the 1950 to 2250-cm?1 region and all are strongly interacting. In the present work we have assigned more than 5000 infrared rotation-vibrational transitions and 163 isotropic Raman transitions from the vibrational ground state to the pentad. We have used infrared and Raman spectra of a resolution better than 0.01 cm?1. From the experimental wavenumbers 2567 pentad rotation-vibrational energy levels with J ≦ 20 have been determined. These levels are reported in the paper. The levels have been used for refinements of the spectroscopic constants of two physically different effective Hamiltonians for the pentad states. For all levels with J ≦ 12 an unweighted standard deviation of 0.004 cm?1 is obtained for both Hamiltonians, whereas the standard deviation increases more or less rapidly with J above 12 due to the imperfections of the Hamiltonians. The values of the spectroscopic constants of both Hamiltonians (85 and 106, respectively) are reported and the effects of the approximations are discussed.  相似文献   

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