共查询到20条相似文献,搜索用时 15 毫秒
1.
R. A. Forber J. Tenenbaum M. S. Feld 《International Journal of Infrared and Millimeter Waves》1980,1(4):527-560
The method of Lamb dip spectroscopy in Stark tuned molecular gases is discussed and applied to the experimental assignment of methyl alcohol infrared transitions in the 5 C–O stretch band. Theoretical expressions for Stark Lamb dip patterns are derived for P, Q and R-branch transitions. Stark tuning results and transition quantum number assignments are presented for several 10m transitions, along with measured values of resonant frequencies, absorption coefficients and pressure broadening coefficients.Work supported by the Army Research Office, Durham, and the National Science Foundation. 相似文献
2.
We have observed narrow (40 MHz) persistent spectral holeburning in SrF2:Sm2+ for Sm2+ ions in perturbed cubic sites. The transition studied is 7F0?5D0 between the f-electron states. Stark effect measurements show a linear splitting with a coefficient of 0.006 MHz/V cm-1 and the splitting pattern shows that the site has C4V symmetry. The C4V perturbation is very weak and leads to unresolved splittings of cubic T1g levels of ~2 cm-1. The nonlinear Zeeman effect was studied using holeburning and the coefficient of 1.04 Hz/G2 shows that the predominant magnetic coupling is in the ground state as found recently for CaF2:Sm2+. 相似文献
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The avoided-crossing molecular-beam electric-resonance technique was applied to methyl silane in the ground torsional state. A new type of anticrossing is introduced which breaks the torsional symmetry and obeys the selection rules ΔJ = 0, K = +1 /a3 ?1. For these “barrier” anticrossings, the values of the crossing fields Ec yield directly the internal rotation splittings; the Ec are independent of the difference (A-B) in the rotational constants. Such anticrossings were observed for J from 1 to 6. Studies were also conducted of several “rotational” anticrossings (J, K) = (1, ±1) /a3 (2, 0) for which Ec does depend on (A-B). The normal rotational transition (J, K) = (1, 0) ← (0, 0) was observed in the ground torsional state using the molecular beam spectrometer. The present data on CH328SiH3 were combined with Hirota's microwave spectra and analyzed with the torsion-rotation Hamiltonian including all quartic centrifugal distortion terms. In addition to evaluating B and several distortion constants, determinations were made of the moment of inertia of the methyl top Iα = 3.165(5) amu-Å2, the effective rotational constant Aeff = 56 189.449(32) MHz, and the effective height of the threefold barrier to internal rotation V3eff = 592.3359(73) cm?1. The correlations leading to these two effective constants are discussed and the true values of A and V3 are determined within certain approximations. For the isotopic species CH330SiH3, barrier and rotational anticrossings were observed. The isotopic changes in A and V3 were determined, as well as an upper limit to the corresponding change in Iα. 相似文献
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Laurie's theory on the coupling between internal rotation and a degenerate vibration in a symmetric-top molecule is examined by investigating the microwave spectra of methyl silane and methyl silane-d3 in the ν12 and ν6 + ν12 states. Two sets of l-type doublets are observed in the J = 2 ← 1, K = 1 transitions; however, the observed frequencies as well as the Stark effects of the l-type doublets indicate definitely that Laurie's expressions for the l-type doublets are to be revised. It is shown theoretically that Coriolis couplings remove discrepancy between theory and experiment; when A1 and A2 denote the rotational constants of CH3 and SiH3 about the symmetry axes and ζ1 and ζ2 measure the magnitudes of angular momenta induced by the ν12 vibration in the two tops, experimental results require that (−A1ζ1 + A2ζ2) is 104 950-107 048 MHz and 45 214-47 626 MHz for CH3SiH3 and CH3SiD3, respectively. 相似文献
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《Journal of Molecular Spectroscopy》1987,126(1):99-112
The effect of the torsional degree of freedom on redundancies in the Hamiltonian and on the dipole operator has been investigated for methyl silane-like molecules. By applying a rotational contact transformation to the torsion-rotation Hamiltonian HTR for the ground vibrational state, a systematic method is demonstrated for treating the redundancies that relate different terms in HTR. In general, with this method, the experimentally accessible molecular parameters in the reduced Hamiltonian can be related to the physically significant molecular parameters in the untransformed Hamiltonian. It is shown that HTR contains a new term which has matrix elements with selection rules (ΔK = ±3), (Δσ = 0), and ΔvT arbitrary, where vT and σ label the torsional levels and sublevels, respectively. As a result of this term, the distortion dipole constant μD which characterizes (ΔK = ±3) matrix elements in C3v molecules cannot, in systems like CH3SiH3, be ascribed entirely to centrifugal distortion but can contain a significant contribution from torsional effects. Furthermore, new transitions can appear in the pure torsional bands which may be strong enough to observe in low barrier molecules. By applying a vibrational contact transformation, the form is derived of the leading torsional terms in the dipole moment expansion. The four dipole distortion constants μ0T, μ2T, μ|;T, and μΛT which characterize these terms are related to the molecular parameters that enter the Coriolis, centrifugal distortion, and anharmonicity contributions to the vibration-torsion-rotation Hamiltonian. 相似文献
9.
The flux of lower state molecules emerging from the cavity of an almost phase locked biharmonic ammonia maser oscillator is found to be amplitude modulated at the biharmonic beat frequency. This molecular state modulation is attributed to periodic pulling phenomena. 相似文献
10.
The dipole moment of D2O has been determined from Stark effect measurements for the 313–220 and 441–532 microwave transitions as 1·857 ± 0·006 and 1·869 ± 0·005D respectively. A rotational dependence of dipole moment has also been established for HDO through μa in the 220–221 and 532–533 transitions; μa was determined as 0·662 ± 0·001 and 0·644 ± 0·001D respectively. The total dipole moment for HDO has been determined from the 321–414 transition to be 1·85 ± 0·01D and to lie within 0·1° of the bisector of the HOD angle. High resolution Stark spectroscopy has been performed on the 624–615 transition of D2O with improved precision using the 337 μm emission line of the HCN laser. This experiment has confirmed the dipole results from the microwave work and the frequency of the 624–615 transition in D2O has been determined as 890 395 ± 3 MHz. The slight increase of dipole moment with deuteration is consistent with the dipole moment for H2O determined from the dielectric constant. This increase is discussed for the vibrational ground state (as for ammonia) in terms of anharmonicity in the bending vibration. The change of μ with rotational transition is interpreted in terms of large changes in molecular geometry for certain rotational states due to centrifugal distortion. 相似文献
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We announce three new rigorous results for the quantum mechanical hydrogen atom in constant magnetic field: (i) Borel summability of the small field perturbation series, (ii) detailed large field asymptotics, and (iii) non-degeneracy of the ground state Ω0 and a proof that it has for all values of the field. 相似文献
13.
Taking into account both the intrinsic curvature and
Zeeman effects, persistent currents in a multi-walled carbon nanotorus
are explored by using a supercell method, within the tight-binding
formalism. It is shown that in the absence of the Zeeman effect, the
intrinsic curvature induces some dramatic changes in energy spectra
and thus changes in the shape of the flux-dependent current. A
paramagnetism--diamagnetism transition is observed. With consideration of
the Zeeman splitting energy, the period of persistent current is
destroyed, and a diamagnetism--paramagnetism transition is obtained
at high magnetic field. In addition, we further explore the effect
of external electric field energy (Eef) on persistent
current, indicating that it changes unmonotonously with Eef. 相似文献
14.
The theory of the vibrational Zeeman effect in symmetric top molecules is presented. It is shown that vibrational g factors may be related to rotational g factors and estimates are made of their magnitude for a number of molecules; these calculations indicate that vibrational Zeeman effects should be observable in symmetric top molecules in degenerate vibrational states. In addition, the novel features of the theory for linear molecules are discussed. 相似文献
15.
分别采用Holtsmark,Neutral Point,Nearest-Neighbor和Mayer模型微场分布函数对Stark线型进行了研究,进而得到相应微场函数下的Stark加宽和频移,研究了4种不同的微场分布函数对Stark加宽和频移的影响。研究结果表明,在电子加宽参数不变时,4种微场分布函数对Stark加宽和频移的影响随离子加宽参数的增加而增加;在离子加宽参数不变时,4种微场分布函数对Stark加宽和频移的影响随电子加宽参数的增加而增加;特别是,当离子加宽参数较大时,Mayer模型微场分布函数对Stark加宽和频移的影响异常明显。这说明,微场分布函数对谱线的加宽和频移的影响在离子与离子碰撞剧烈的等离子体环境中尤其显著, 在这样的等离子体环境中,进行等离子体诊断时,选择合适的微场分布函数非常重要。结果对等离子体诊断有一定参考价值。 相似文献
16.
This paper examines the Stark effect, as a first order perturbation of manifestly covariant hydrogen-like bound states. These bound states are solutions to a relativistic Schrödinger equation with invariant evolution parameter, and represent mass eigenstates whose eigenvalues correspond to the well-known energy spectrum of the nonrelativistic theory. In analogy to the nonrelativistic case, the off-diagonal perturbation leads to a lifting of the degeneracy in the mass spectrum. In the covariant case, not only do the spectral lines split, but they acquire an imaginary part which is linear in the applied electric field, thus revealing induced bound state decay in first order perturbation theory. This imaginary part results from the coupling of the external field to the non-compact boost generator. In order to recover the conventional first order Stark splitting, we must include a scalar potential term. This term may be understood as a fifth gauge potential, which compensates for dependence of gauge transformations on the invariant evolution parameter. 相似文献
17.
A mesoscale Aharonov-Bohm (AB) ring with a quantum dot (QD) embedded in each arm is computationally modeled for unique transmission properties arising from a combination of AB effects and Zeeman splitting of the QD energy levels. A tight-binding Hamiltonian is solved, providing analytical expressions for the transmission as a function of system parameters. Transmission resonances with spin-polarized output are presented for cases involving either a perpendicular field, or a parallel field, or both. The combination of the AB-effect with Zeeman splitting allows sensitive control of the output resonances of the device, manifesting in spin-polarized states which separate and cross as a function of applied field. In the case with perpendicular flux, the AB-oscillations exhibit atypical non-periodicity, and Fano-type resonances appear as a function of magnetic flux due to the flux-dependent shift in the QD energy levels via the Zeeman effect. 相似文献
18.
We report observation of the scattered spectrum from a Zeeman degenerate atom at high laser intensities. For a J = 0 to J = 1 transition in the presence of collisions we observe an asymmetric triplet in the polarization parallel to the incident laser and an asymmetric doublet in the polarization perpendicular to the incident laser. 相似文献
19.
Enrico Lipparini Manuel Barranco 《Physica E: Low-dimensional Systems and Nanostructures》2007,36(2):190-193
We show that when a two-dimensional interacting electron gas is submitted to a perpendicular magnetic field, the application of an in-plane electric field E induces a spin current perpendicular to E whose conductivity is quantized. This current can lead to spin accumulation that might be detected by means of optical experiments. The appearance of this intrinsic spin-Hall effect is crucially based on the validity of Kohn's theorem and on the presence of the Zeeman term in the electron Hamiltonian. The possibility of resonant effects in the spin-Hall conductivity due to the combined effect of Rashba and Dresselhaus spin–orbit couplings is discussed. 相似文献
20.
The g-factors of the 23P, 21P, and 33P states of the helium atom are calculated by using the vatiational wave functions constructed from the linear combinations of Slater-type basis sets. The relativistic corrections to order α2(a.u.) and the effect of the motion of the center of mass are treated by using first-order perturbation theory. Most of our predicted results are in good agreement with recent results of Yan and Drake, which were obtained by using the wave functions with doubled Hylleraas coordinates. Based on the analysis of the convergence pattern in our calculation, we believe that our predicted value of the δgL-factor for 33P state in 4He, 2.914 15×10-7, ought to be reasonable and accurate, although there are no corresponding experimental data available in the liteature yet to be compared with. 相似文献