Measurement of the electric dipole moment of NO (X2 Π ν = 0,1) by mid-infrared laser magnetic resonance spectroscopy

A pair of parallel Stark plates are added to a CO laser magnetic resonance spectrometer to apply electric field in the absorption cell. This apparatus is used to measure the molecular electric dipole moment via Zeeman and Stark effects simultaneously. The saturated absorption spectra of NO (X²Π_3/2, ν = 1 ← 0) was observed and the electric dipole moments of NO were directly measured in the presence of an electric field. The dipole moments are determined as μ₀(ν = 0) = 0.1595(15) D, μ₁ (ν = 1) = 0.1425(16) D. The electric dipole moment of the vibrationally excited state (ν = 1) is determined for the first time. The dependence of the electric dipole moments on its nuclear distances is interpreted.     

Measurement of the dipole moment of CF3CN

The Stark effect was observed for K = 0 and K = 1, J = 1 → 2 transitions in CF₃CN. Measurements were made in a Stark modulated microwave spectrometer. The dipole moment obtained was μ = 1.262 ± 0.010 D. An analysis of the effects of electric field inhomogeneities on the observed Stark shifts for K = 0 and K = 1 states is included. Appropriate corrections are given for measuring linear Stark effects in a standard waveguide cell calibrated using a molecule with second-order Stark effect.     

“Artificial vacuum” for T-violation experiment

We point out the possible use of matrix isolation spectroscopy in experimental tests of fundamental physics. As a concrete example we show how this technique might be applied to measuring the T-violation electron electric dipole moment d_e. We estimate that a dipole moment could be detected down to d_e ∼ 6 × 10⁻²⁸e cm, in comparison to the current limit of d_e < 10⁻²⁴e cm.     

Laser Stark and diode laser spectroscopy of the 10-μm bands of CH2NH: Determination of the dipole moment orientation

The complexities apparent in the laser Stark spectra obtained from the 10-μm band system of CH₂NH are shown to be due to the interplay of the a and b components of the Coriolis and Stark effect coupling. As a result it has been possible to determine the relative orientations of the a and b components of the permanent electric dipole moment. This is analogous to the determination of the relative signs of the dipole moment derivatives from the analysis of the intensity perturbations produced by Coriolis interaction.A detailed comparison has also been made of the uses of laser Stark, diode laser, and Fourier transform spectroscopy for studying heavily perturbed molecular spectra.     

FTMW spectroscopy of jet-cooled 9-cyanoanthracene

Rotational spectrum of jet-cooled 9-cyanoanthracene has been observed in the 4-8 GHz region with a Fourier-transform microwave spectrometer. The present observation of 25 low-J transitions with J^′′?11 has confirmed the previous results on the rotational constants of the ground state determined by rotational coherence spectroscopy [J. Phys. Chem. A. 105 (2001) 1131] and provided the values with significantly improved precision. An accurate set of hyperfine splitting constants is also reported for the ¹⁴N nuclear quadrupole coupling. The electric dipole moment was determined from Stark effect measurements on several split components: μ_b(=μ)=4.406(7) D.     

Laser Stark spectroscopy; a case study in the ν2 fundamental band of 14NH3

The ν₂ fundamental band of ¹⁴NH₃ is observed with a laser Stark spectrometer in Doppler-limited resolution. A set of 41 constants including the electric dipole moment and its rotational dependence are determined from 360 Stark resonances observed in the present work and 67 millimeter- and submillimeter-wave inversion and rotation-inversion lines reported in the literature. The rms residual of the fit is 3.1 × 10⁻⁴ cm⁻¹. Field-free transition frequencies of the band in the region 800–1160 cm⁻¹ are calculated from the constants and tabulated together with their estimated uncertainties and relative absorption intensities. Rotational dependence of the electric dipole matrix elements of a C_3v molecule is presented on the basis of the conventional theory of vibration-rotation.     

Laser stark spectroscopy of the ν2 fundamental band of 15NH3

The ν₂ fundamental band of ¹⁵NH₃ has been observed with a laser Stark spectrometer in Doppler-limited resolution. A set of 38 band constants including the electric dipole moment and its rotational dependence are determined from 416 Stark resonances observed in the present work and three submillimeter lines reported in the literature. The ν₂-band absorption line frequencies in the region 800–1160 cm⁻¹ and their relative absorption intensities are estimated from the band constants.     

High-resolution laser Stark and Fourier transform spectroscopy of the ν2 fundamental band of HFCO

The ν₂ (CO stretch) fundamental band of formyl fluoride (HFCO) was studied in the region 1800 to 1910 cm^?1 using the two techniques of intracavity CO laser Stark spectroscopy at sub-Doppler resolution and Fourier transform spectroscopy at Doppler-limited resolution. Accurate values of the molecular parameters of the ground and excited (v₂ = 1) vibrational states were obtained from a combined fit of the ν₂ band data and available microwave data. The results include precise determinations of the electric dipole moment components (μ_a and μ_b) of HFCO in the ground and excited states.     

铯原子里德堡态Stark能量及电偶极矩的测量和理论计算

里德堡原子由于具有体积大、寿命长、易极化及在外电场中能级易于操控等特点, 已经成为了目前物理学领域研究的热点之一. 本文在磁光阱中实验测量了铯原子15P_3/2和16P_3/2态的Stark光谱,根据光谱给出了15P_3/2和16P_3/2|m|=1/2 Stark态在0-1400 V/cm场强范围适用的Stark 能量和偶极矩的经验性解析表达式; 用数值方法求解薛定谔方程获得了这些态的Stark能量、偶极矩和电子几率密度分布. 电子几率密度分布定性说明了计算的偶极矩矢量的方向是正确的. 计算的Stark能量、偶极矩与实验结果相一致.     

Effect of external electric field on R line absorption spectra in LiNbO3:Cr3+ crystals

The effect of an external electric field on the R absorption lines of LiNbO₃:Cr³⁺ crystals has been studied by a high-sensitivity differential technique at 77 K. Linear Stark effect has been observed in a field directed along the trigonal crystal axis. No effect of the field was observed when directed perpendicular to this axis. These characteristics of the Stark effect provide a convincing argument for the electric dipole moments of Cr³⁺ centers being oriented along the trigonal C ₃ axis of the crystal and indicate that the chromium centers in LiNbO₃ have C ₃ symmetry. Fiz. Tverd. Tela (St. Petersburg) 39, 2053–2056 (November 1997)     

High-resolution measurements of the 1 ← 0 infrared absorption band of hydrogen iodide

The ν₁ fundamental band of FNO has been studied by the technique of CO laser Stark spectroscopy. The band origin was determined to be 1844.099 cm^?1, and values for the rotational and centrifugal distortion constants of the (100) excited vibrational state were found. The ground state dipole moment components were determined to be μ_a = 1.690 and μ_b = 0.370 D, for a total dipole moment of 1.730 D, and a relatively large reduction (5%) was found in μ for the (100) state relative to the ground state.     

Die Abhängigkeit innerer und äußerer Wechselwirkungen des TlF-Moleküls von der Schwingung,Rotation und Isotopie

The hyperfinestructure, Stark effekt and Zeeman effect of the TlF molecule have been measured with a molecular beam resonance apparatus. The apparatus uses electric four poles as deflecting fields and a homogeneous electric field parallel to a super-imposed magnetic field in the transition region. Electric dipole transitions withΔm _J =±1,ΔJ=0 (J rotational quantum number) were measured in the following (v, J) states (v vibrational quantum number): (0,1), (1,1), (2,1) and (0,2) of the molecule²⁰⁵Tl¹⁹F and (0,1) of the molecule²⁰³Tl¹⁹F. For these five states the following interaction constants were determined: The magnetic (and the electric) dipolemoment of the molecule, the scalar and the tensor nuclear dipole-dipole interaction, the nuclear spin-rotational interactions, the anisotropy of the diamagnetic susceptibility ξ_⊥?ξ_∥, the anisotropy of the diamagnetic shielding of the external field by the electrons at the position of the nuclei σ_⊥?σ_∥. From these quantities it was possible to calculate the quadrupole-moment of the electronic charge distribution. Furthermore, the dependence of the ratio of the isotopic electric dipolemoments on vibrational state was measured. A new method for determining the nuclear magnetic moments is described. The method consists of a molecular beam resonance apparatus with combined magnetic and electric transition fields and was used to measure the magnetic moments of the nuclei²⁰⁵Tl and¹⁹F. — On page 293 will be found a table of results.     

Modulation of the shape of the photon echo pulse by a pulsed magnetic field: Zeeman splitting in LuLiF4:Er3+ and YLiF4:Er3+

A spectroscopy method has been proposed involving a change in the time shape of the echo signal in the presence of a perturbation, which splits the frequencies of the transitions of two or more ion subgroups of the echo-active ions. This method has been applied to optical systems in which the Zeeman effect is manifested. The ion transition frequencies of ions are switched by a weak pulsed magnetic field acting during the time of the radiation of the photon echo pulse. The modulation of the photon echo signal shape was observed in LuLiF₄:Er³⁺ and YLiF₄:Er³⁺. The time interval between the two nearest minima corresponds to the accumulated phase of the electric dipole moment ?? and makes it possible to determine the difference of the g factors of the ground and excited ⁴ F _9/2(I) states of the Er³⁺ ion in the LuLiF₄ the YLiF₄ matrices for the known amplitude of the pulsed magnetic field. It has been shown that the echo response of the system can be programmed by the weak magnetic field pulses.     

Use of the anomalous Stark effect for the approximate determination of torsional energy splittings

An advantageous use of the anomalous Stark effect for the determination of the torsional energy splittings is proposed. The method is applicable in those cases where the dipole moment component connecting the torsional states of different parity has an experimentally observable magnitude. The analysis of the Stark spectrum observed in the spectrum of the N-cis lone-electron-pair gauche isomer of allylamine is presented as an example. The Stark effects of those transitions (a-type and b-type) which are inside the same vibrational state (0⁺ and 0^?), are used for the fitting of the μ_a, μ_b, and μ_c dipole moment components as well as the torsional energy splitting Δν_tors. The values obtained are compared to more accurate values derived by other methods. The possible use for predicting large torsional splittings is discussed.     

Electric field effects in the EPR spectrum of low-spin Ni<Superscript>3+</Superscript> centers in the KTaO<Subscript>3</Subscript> crystal

The electric field effects in the EPR spectra of low-spin (S = 1/2) Ni³⁺ tetragonal centers in KTaO₃ single crystals are investigated. It is revealed that the resonance lines are split and the centers are oriented as a result of the interaction of the external field with the electric dipole moment of the center. The dipole moment of the center is determined to be p = 100 D = 21 e?. An analysis of the set of experimental data obtained permits one to choose correctly the microscopic models for two nickel centers in KTaO₃ crystals among the models discussed in the literature. Original Russian Text ￠ L.S. Sochava, S.A. Basun, V.é. Bursian, A.G. Razdobarin, D.R. Evans, 2007, published in Fizika Tverdogo Tela, 2007, Vol. 49, No. 12, pp. 2157–2160.     

An atomic linear Stark shift violating P but not T arising from the electroweak nuclear anapole moment

We propose a direct method of detection of the nuclear anapole moment. It is based on the existence of a linear Stark shift for alkali atoms in their ground state perturbed by a quadrupolar interaction of uniaxial symmetry around a direction and a magnetic field. This shift is characterized by the T-even pseudoscalar ( ^. )(∧ ^. )/B ². It involves on the one hand the anisotropy of the hyperfine interaction induced by the quadrupolar interaction and, on the other, the static electric dipole moment arising from electroweak interactions inside the nucleus. The case of ground state Cs atoms trapped in a uniaxial (hcp) phase of solid ⁴He is examined. From an explicit evaluation of both the hyperfine structure anisotropy and the static dipole deduced from recent empirical data about the Cs nuclear anapole moment, we predict the Stark shift. It is three times the experimental upper bound to be set on the T-odd Stark shift of free Cs atoms in order to improve the present limit on the electron EDM. Received 20 December 2000     

Paraelectric alignment of NH 2 - centres in alkali halide crystals

The low temperature paraelectric alignment of substitutional NH ₂ ^- dipole centres in alkali halide crystals is studied measuring the electric field induced variation of the UV absorption and the electro-birefringence (Kerr-effect). We obtain the magnitude of the electric dipole moment and of the anisotropy of the oscillator strength. The reorientation of the dipoles between their equilibrium orientations is investigated by measuring the time dependence of the electro-birefringence after rapid changes of the applied electric field. The results indicate the predominance of one-phonon assisted tunneling processes.     

Modeling non-Lorentzian two-photon absorption line shape in dipolar chromophores

We present a new approach to modeling of homogeneous line shape in two-photon absorption (2PA) spectra of chromophores with large permanent dipole moment difference between the ground- and excited electronic states using numerical solution of stochastic two-level density matrix equation of motion. Good agreement with experimental 2PA line shapes is obtained for S₁←S₀ transition of Styryl 9 M, which allows us to estimate that the permanent dipole moment difference varies in this chromophore within the S₁←S₀ band in the range, Δμ=12-25 D.