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1.
The electronic absorption spectra of thioformaldehyde and thioformaldehyde-d2 have been obtained. A vibrational analysis of the discrete band system in the 6100-4400-Å region is reported. The type A origin bands are at 16 39416 484cm?1 for CH2SCD2S, and are magnetic dipole allowed. The electronic transition is A?1A2-X?1A1 under the C2v point group. Most of the intensity of the system is in type B bands, and is due to vibronic mixing with higher 1B2 states when the inversion mode ν4 is excited. The molecule in the excited 1A2 state is “floppy-planar,” having a broad potential function with a barrier of the order of 20 cm?1 to the inversion motion.  相似文献   

2.
The magnetic specific heat of ferrous formate dihydrate is analysed on the basis of a model, SA = 12 and SB = 2. The experimental result turns out to be well explained by the introduction of a large S4z-term for B site ions.  相似文献   

3.
The first observation of the ESR spectra of Mn2+, entering substitutionally for Fe2+ in the Van Vleck paramagnet FeS2 (polycrystals), is reported. The data from 5 to 295 K fits the spin-Hamiltonian hs = gβH·S + [S2z?13 S(S + 1)] + AS·I, with g = 2.000 ± 0.001, A/β = ?95.0 ± 0.5 Oe and D/β varying from 50 Oe (5K) to 59 Oe (295 K). The temperature dependence of D can be described in terms of a single phonon-mode with frequency ? 145 cm?1.  相似文献   

4.
The helicity, h?, of μ? in π-decay has been determined as positive (h??+0.90) from the average polarization, Pav≡〈JB·sμ〉, of 12B produced in the μ?+12C→νμ+12B reaction. We obtain also dynamical information on μ-capture: (i) the weak magnetism form factor, μ=4.5±1.1, and (ii) the sum of the induced pseudoscalar (gp) and the 2nd class induced tensor (gT) couplings versus gA, (gP+gT)gA=7.1±2.7. The latter result, adopting the “canonical” value of gPgA, leads to gTgA=+1±2.7 which is compatible with zero and in strong contradiction with the value ?—6 recently advocated by Kubodera, Delorme and Rho.  相似文献   

5.
The polarized low-temperature crystal absorption spectra of tetramethyl-1,3-cyclobutanedithione-h12 and -d12 have been measured in the visible region, and 1 excited states identified as follows: 3Au with origin (h12d12) at 16 82916 836cm?1; 1Au and 1B10 with nearly degenerate origins near 18 000 cm?1; and probably 1Au and 1B1g near 19 500 cm?1. The singlet excited states lie close together and perturb each other strongly. As in the corresponding dione, CHCD stretching vibrations of the substituent methyl groups are active in intensity borrowing, and the effects of excitation are delocalized over the entire molecule.  相似文献   

6.
Two new systems of emission bands near 2100 and 3100 Å have been produced by a microwave discharge in B2S3 vapor. From the known X2Σ+ and A2Πi states of BS, these systems have been assigned as E2Σ+X2Σ+ and E2Σ+A2Πi. Constants in cm?1 for the new state are
E2±: Te = 47 929.3, Be = 0.671 (λe = 1.752 A), αe = 0.008
,  相似文献   

7.
A millimeter-wave spectrometer having a sensitivity of 4 × 10?10 cm?1 in the 2-mm region has been constructed for observation of extremely weak millimeter-wave spectra of gases. It has been used to measure JJ, K = 0 ← 3 transitions in PH3 and JJ, K = 0 ← 3 as well as K = ±1 ← ±4 transitions in PD3. The B0 and C0 spectral constants (in MHz) are: for PH3, B0 = 133 480.15 ± 0.12 and C0 = 117 488.85 ± 0.16; for PD3, B0 = 69 471.10 ± 0.03 and C0 = 58 974.37 ± 0.05. The effective ground-state values obtained for the bond angle and bond length are: for PH3, r0 (A?) = 1.4200 and α0(o) = 93.345; for PD3, r0 (A?) = 1.4176 and α0(o) = 93.359. The corresponding zero-point-average values were calculated to be: for PH3, rz (A?) = 1.42699 ± 0.0002 and αz(o) = 93.2287; for PD3, rz (A?) = 1.42265 ± 0.0001 and αz(o) = 93.2567 ± 0.004. For both species, the equilibrium values are re (A?) = 1.41159 ± 0.0006 and αe(o) = 93.328 ± 0.02.  相似文献   

8.
Departure from stoichiometry in vapor grown FeCr2S4 was studied using Mössbauer spectroscopy. The paramagnetic Mössbauer spectra give evidence of two singlets and two doublets which correspond respectively to A site Fe2+ ? Fe3+, FeII in Td symmetry and in symmetry lower than Td. The following ionic distribution has been deduced:
(Fe2+1?yFe3+y)|Cr3+2?xx|S4?zz
Compounds in the system Fe1+xCr2?xS4 have been studied for 0 ? x ? 0.1. The spectra are solved assuming FeII in A site with Td symmetry, A site FeII with lower symmetry and B site Fe3+. No Fe2+ appears in B site. These features are discussed in terms of schematic band structures implying single electron narrow bands. The non-affinity of Fe2+ for B sites of iron thiochromites is discussed in relation with B site Cr2+ level.  相似文献   

9.
A rotational assignment of approximately 80 lines with Ka′ = 0, 1, 2, 3, and 4 has been made of the 593 nm 2A12B2 band of NO2 using cw dye laser excitation and microwave optical double-resonance spectroscopy. Rotational constants for the 2B2 state were obtained as A = 8.52 cm?1, B = 0.458 cm?1, and C = 0.388 cm?1. Spin splittings for the Ka′ = 0 excited state levels fit a simple symmetric top formula and give (?bb + ?cc)2 = ?0.0483 cm?1. Spin splittings for Ka′ = 1 (N′ even) are irregular and are shown to change sign between N′ = 6 and 8. Assuming that the large inertial defect of 4.66 amu Å2 arises solely from A, a structure for the 2B2 state is obtained which gives r (NO) = 1.35 A? and an ONO angle of 105°. Alternatively, weighting the three rotational constants equally gives r = 1.29 A? and θ = 118°.  相似文献   

10.
The rz structure of phosgene has been determined by a joint analysis of the electron diffraction intensity and the rotational constants as follows: rz(CO) = 1.1785 ± 0.0026 A?, rz(CCl) = 1.7424 ± 0.0013 A?, ∠z;ClCCl = 111.83 ± 0.11°, where uncertainties represent estimated limits of experimental error. The effective constants representing bond-stretching anharmonicity have been obtained from an analysis of the isotopic differences in the rz structure: a3(CO) = 2.9 ± 0.9 A??1, a3(CCl) = 1.6 ± 0.4 A??1. The equilibrium bond distances have been estimated from the rz structure for the normal species and from the anharmonic constants to be re(CO) = 1.1756 ± 0.0032 A?, re(CCl) = 1.7381 ± 0.0019 A?.  相似文献   

11.
The E-B (0g+-0u+) band system of Br2 has been investigated at Doppler-limited resolution using polarization labeling spectroscopy. Merged E state data for the three naturally occurring isotopes in the range vE = 0–16, expressed in terms of the constants for 79Br2, are (in cm?1) Y0,0 = 49 777.962(54), Y1,0 = 150.834(22), Y2,0 = ?0.4182(28), Y3,0 = 6.6(11) × 10?4, Y0,1 = 4.1876(28) × 10?2, Y1,1 = ?1.607(16) × 10?4, and Y0,2 = 1.39(39) × 10?8. The bond distance is re = 3.194 A?, and the diabatic dissociation energy to Br+(3P2) + Br?(1S0) is 34 700 cm?1.  相似文献   

12.
Using a solution to the inverse scattering problem we have generated phase-equivalent separable potentials in the 1S0 and 3S1?3D1 states, which have nearly the same singlet UPA form factors and deuteron parameters (ED, PD, QD, AS and ADAS) as the Reid soft-core potential. We compare our results for the binding energy of the triton and the neutron-deuteron doublet scattering length with the corresponding values for the Reid soft-core potential.  相似文献   

13.
The activation barrier ΔE1ABfor dissociation AB → A + B on transition-metal surfaces is analyzed within an additive Morse-type approach based on the bond-order conservation. It is shown that ΔE1AB = DAB?(QA + QB + QAQB/(QA + QB) where DAB is the gas-phase dissociation energy and QA(QB) is the heat of atomic chemisorption. Estimates of ΔE1 for H2, N2, O2, and NO are shown to be in reasonable agreement with experiment. The two-dimensional potential diagram of the metal-AB interactions is defined analytically and discussed in some detail.  相似文献   

14.
Oscillator strengths for 11S?n1P transitions for some members of the helium isoelectronic sequence have been calculated by utilizing the dipole length, velocity and acceleration forms of the transition matrix element with coupled H.F. wave functions. Good agreement has been obtained between the values of the oscillator strengths. The quantities (?A??L) and (?A??V) decrease slowly with nuclear charge Z, whereas (?L-?V) first increase to a maximum value and then decreases slowly.  相似文献   

15.
Angular distributions of six polarization transfer coefficients Kxx′(θ), kxz′(θ), Kzx?(θ), Kzz?(θ), and Kyyy?(θ); of the four analyzing powers Ay(θ), Axx(θ), Ayy(θ), and Azz(θ); and of the polarization function Pý(θ), have been measured atEd = 10.00 MeV for the reaction 2H(d, n)3He. Measurements were made for neutron lab angles between 0° and 80° in 10° steps. Additionally the y-axis associated quantities were measured at θ1ab = 99°. Most of the measured coefficients are large at some angles and all show considerable variation with angle.  相似文献   

16.
Mössbauer emission spectra of a frozen aqueous solution of 57CoCl2 show contributions from the Sz = +52 and the Sz = +32 Zeeman levels of Fe3+ ions at T = 4.2 K in H ? 30 kG. The K-capture results in a non-equilibrium state of relaxation time comparable to the lifetime of the nuclear excited state (~ 10?7 s).  相似文献   

17.
The recent increase of experimental data concerning the giant monopole resonance energy EM gives information on the incompressibility modulus of nuclear matter, provided one can extrapolate the incompressibility of a nucleus KA, defined by EM =[h?2KA/m〈r2〉]12, to the infinite medium. We discuss the theoretical interpretation of the coefficients of an A?13 expansion of KA by studying the asymptotic behaviour of two RPA sum rules (corresponding to the scaling and the constrained model), evaluated using self-consistent Thomas-Fermi calculations. We show that the scaling model is the most suitable one as it leads to a rapidly converging A?13 expansion of the corresponding incompressibility KAs, whereas this is not the case with the constrained model. Some semi-empirical relations between the coefficients of the expansion of KAs are established, which reduce to one the number of free parameters in a best-fit analysis of the experimental data. This reduction is essential due to the still limited number and accuracy of experimental data. We then show the compatibility of the data given by the various experimental groups with this parametrization and obtain a value of Kn.m. = 220 ± 20 MeV, in good agreement with more microscopic analyses.  相似文献   

18.
The 0-0, 1-1, 2-2, and 3-3 bands of the A2Π-X2Σ+ transition of the tritiated beryllium monohydride molecule have been observed at 5000 Å in emission using a beryllium hollow-cathode discharge in a He + T2 mixture. The rotational analysis of these bands yields the following principal molecular constants.
A2Π:Be = 4.192 cm?1; re = 1.333 A?
X2Σ:Be = 4.142 cm?1; re = 1.341 A?
ωe′ ? ωe″ = 16.36 cm?1; ωe′Xe′ ? ωe″Xe″ = 0.84 cm?1
From the pure electronic energy difference (EΠ - EΣ)BeT = 20 037.91 ± 1.5 cm?1 and the corresponding previously known values for BeH and BeD, the following electronic isotope shifts are derived
ΔEei(BeH?BeT) = ?4.7 ≠ 1.5cm1, ΔEei(BeH?BeT) = ?1.8 ≠ 1.5cm1
and related to the theoretical approach given by Bunker to the problem of the breakdown of the Born-Oppenheimer approximation.  相似文献   

19.
The pure rotational spectra of three deuterated ethylenes, CH2CD2, CH2CHD, and cis-CHDCHD, were observed by microwave spectroscopy, and the rotational and centrifugal distortion constants were determined precisely. The dipole moment of CH2CD2 was calculated from the Stark effects to be 0.0091 ± 0.0004 D. From the observed rotational constants the average structure was calculated to be rz(CC) = 1.3391 ± 0.0013 A?, rz(CH) = 1.0869 ± 0.0013 A?, θz(CCH) = 121.28 ± 0.10°, and rz(CH) - rz(CD) = 0.00137 ± 0.00037 A?, where the errors include one standard deviation in the fitting and errors due to an uncertainty (±0.03°) in θz(CCH) - θz(CCD).  相似文献   

20.
New fluorescence excitation and dispersed SVL fluorescence spectra of s-tetrazine vapor in supersonic expansions of helium and argon are reported. A forbidden in-plane-polarized component of the A?1B3u-X?1Ag transition is discovered at (0, 0) + 578 cm?1 with a type-B band contour in rotationally resolved excitation spectra obtained with a single-frequency cw ring dye laser. Linewidth measurements of single rovibronic transitions provide data to calculate lifetimes of low-lying S1 vibronic states of the isolated molecule. Depending on the vibrational mode involved, the lifetime varies from 0.05 to greater than 1 nsec. The number of cold-band assignments in the absorption spectrum of s-tetrazine vapor now confirmed by analysis of SVL fluorescence spectra increases from three to ten.  相似文献   

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