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Within the general axially nonadiabatic channel approach described in Paper I of this series [M. Auzinsh, E. I. Dashevskaya, I. Litvin, E. E. Nikitin, and J. Troe, J. Chem. Phys. 139, 084311 (2013)], the present article analyzes the simultaneous manifestation of electrostatic and gyroscopic interactions in the quantum capture of dipolar polarizable symmetric top molecules by ions. As a demonstration, the rate coefficients for capture of CH3D and CD3H by H+, D+, and H3+ are calculated. [ABSTRACT FROM AUTHOR]

The rate coefficients for capture of charged particles by dipolar polarizable symmetric top molecules in the quantum collision regime are calculated within an axially nonadiabatic channel approach. It uses the adiabatic approximation with respect to rotational transitions of the target within first-order charge-dipole interaction and takes into account the gyroscopic effect that decouples the intrinsic angular momentum from the collision axis. The results are valid for a wide range of collision energies (from single-wave capture to the classical limit) and dipole moments (from the Vogt-Wannier and fly-wheel to the adiabatic channel limit). [ABSTRACT FROM AUTHOR]

Following our general approach to Λ-doubling specificity in the capture of dipolar molecules by ions [M. Auzinsh et al., J. Chem. Phys. 128, 184304 (2008)], we calculate the rate coefficients for the title process in the temperature range 10-4≤T≤102 K. Three regimes considered are as follows: (i) nonadiabatic capture in the regime of high-field Stark effect with respect to the Λ-doubling components, (10-1≤T≤102 K), (ii) adiabatic capture in the regime of intermediate Stark effect (10-3≤T≤10-1 K), and (iii) adiabatic capture in the limit of very low temperatures (T<10-3 K) in the regime of quadratic Stark effect with respect to the Λ-doubling and hyperfine components. The results predict a high specificity of the capture rates with respect to the Λ-doublet states even under conditions when the collision energy of the partners strongly exceeds the Λ-doubling splitting [ABSTRACT FROM AUTHOR]

The low-energy capture of a dipolar diatomic molecule in an adiabatically isolated electronic state with a good quantum number Ω (Hund’s coupling case a) by an ion occurs adiabatically with respect to rotational transitions of the diatom. However, the capture dynamics may be nonadiabatic with respect to transitions between the pair of the Λ-doubling states belonging to the same value of the intrinsic angular momentum j. In this work, nonadiabatic transition probabilities are calculated which define the Λ-doubling j-specific capture rate coefficients. It is shown that the transition from linear to quadratic Stark effect in the ion-dipole interaction, which damps the T-1/2 divergence of the capture rate coefficient calculated with vanishing Λ-doubling splitting, occurs in the adiabatic regime with respect to transitions between Λ-doubling adiabatic channel potentials. This allows one to suggest simple analytical expressions for the rate coefficients in the temperature range which covers the region between the sudden and the adiabatic limits with respect to the Λ-doubling states. [ABSTRACT FROM AUTHOR]

The paper analyzes magnetic field induced alignment–orientation conversion (AOC) phenomenon caused by simultaneous effect of quadratic terms in Zeeman energy shift and magnetic predissociation (PD), producing asymmetry either in energy splitting ωMM±1≠ω-M∓1-M or in relaxation of coherence ΓMM±1≠Γ-M∓1-M between coherently excited M, M±1 magnetic sublevels. The AOC is registered via the appearance of circular polarization (C) of fluorescence under linearly polarized excitation. The unified perturbation treatment of a molecule in external magnetic field B is presented, accounting for magnetic and intramolecular perturbations via interaction with bonded or continuum states, considering Hund’s (c)-case coupling and dividing the intramolecular perturbation operator into homogeneous (ΔΩ=0) and heterogeneous (ΔΩ=±1) parts. Explicit expressions up to B2 terms are given for energy shift and PD rate, adapted to 1u state in conditions relevant to the B 3Σ-u complex of Te2 molecule. Numeric simulation revealed that nonlinear magnetic energy shift and heterogeneous magnetic PD produce dispersion type fluorescence circularity signals C(B) of different sign. Fitting of experimental data on B1-u, v(J)=2(96) state of 130Te2 molecule allowed to determine the electronic matrix element of paramagnetic Hamiltonian (Ω=0|Ĥpm|Ω=1)≡G±=2.7, as well as the natural Cvhet=±6 s-1/2 and the magnetic αvhet=∓9×103 s-1/2 T-1 rate constants of heterogeneous PD, supposing that the B1-u state PD takes place through 0-u state continuum. As a result, magnetic AOC represents a sensitive method to investigate molecular structure and intramolecular interaction between both bonded and continuum states. Additionally, it has been shown that the magnetic PD effect leads to strong amplification of nonzero field level crossing signals caused by B2 terms... [ABSTRACT FROM AUTHOR]

We discuss quantum beats in electronically excited molecular states with high rotational angular momenta J appearing in time resolved fluorescence in conditions of quadratic and linear energy shift dependence on magnetic quantum number M and external field strength. Density matrix formalism is used to obtain in explicit form the expressions for time dependent fluorescence intensity after δ-function pulsed excitation. In case of pure quadratic Stark effect, which is typical for 1Σ state diatomics, excited state quantum beats for J>1 exhibit a regular, or ‘‘grill’’ structure, consisting of narrow equidistant ‘‘principal’’ peaks with equal relative amplitudes on the exponential decay background. At linear polarized excitation the time intervals between the adjacent peaks are 2π/ω20, ω20 being the splitting frequency between coherently excited M-sublevels with M=2 and M’=0. If an admixture of linear contribution is present in field induced level shifts, the grill structure is superimposed by a single frequency harmonic modulation. A special geometry was found in which the quadratic beats are fully absent and the modulated grill pattern is brought into existence only by the influence of linear term. Such a case takes place when the light polarization vector in fluorescence is directed at 45° angle with respect to the exciting light polarization vector and yields the most sensitive way to separate quadratic and linear contribution. We considered the examples when the first order term appears by a combined action of electric and magnetic field, as well as due to the e–f level electric field induced mixing, with the parameters typical for the NaK molecule. [ABSTRACT FROM AUTHOR]

General conditions causing partial transformation of optical alignment of excited state angular momenta J into orientation at weak linear polarized broad line excitation of molecules are examined. As is shown, the phenomenon takes place under the effect of an external perturbing factor leading to such magnetic sublevel M splitting ω[sub MM′] when ω[sub MM±1]≠ω[sub -M≠1-M] and ω[sub MM′] is of the order of molecular state relaxation rate. An analytical expression is obtained describing the appearing circularity of fluorescence for arbitrary J values. A numeric example is given for [sup 1]∑ state molecules with J=10 assuming a quadratic Stark effect in a homogeneous external electric field. [ABSTRACT FROM AUTHOR]

Examines the empirical and ab initio approach of lifetimes and electron transition dipole moment functions. Usage of lifetime data accounting in the improvement of the empirical function; Application of the combined finite-field technique and perturbation theory for ab initio all-electron transition calculations; Effect of approach on calculation reliability.

Presents the first permanent electric dipole moment measurements for sodium and potassium state rovibronic levels. Existence of spectroscopic information including lifetime measurements; Theoretical description of the Stark effect; Simulation of expected signals in laser-induced fluorescence.

In this paper we present a device for measuring the magnetic field and its gradient with a spatial resolution of several hundred nanometres. This device is based on caesium metal vapour confined to an extremely thin cell (ETC). To measure magnetic signals, we use absorption and very low laser powers, which might be appealing for modern fabrication techniques. A portable, fully automated device was constructed. [ABSTRACT FROM AUTHOR]

The rate coefficients for capture of charged particles by spherical top molecules, which by isotopic substitution become symmetric top molecules with small dipole moment, are expressed analytically for the two limiting cases of weak coupling of the molecular angular momentum to the collision axis (dominating Coriolis interaction, the fly-wheel [FW] approximation) and strong coupling (negligible Coriolis interaction, the adiabatic channel [AC] approximation). The comparison leads to relations between rate coefficients for ultra-low (FW) and moderate (AC) temperatures and defines the range of parameters for which the analytical expressions become insufficient and a numerical treatment is necessary. [ABSTRACT FROM AUTHOR]

Abstract: We present an experimental and theoretical study of nonlinear magneto-optical resonances observed in the fluorescence to the ground state from the 7P 3/2 state of cesium, which was populated directly by laser radiation at 455nm, and from the 6P 1/2 and 6P 3/2 states, which were populated via cascade transitions that started from the 7P 3/2 state and passed through various intermediate states. The laser-induced fluorescence (LIF) was observed as the magnetic field was scanned through zero. Signals were recorded for the two orthogonal, linearly polarized components of the LIF. We compared the measured signals with the results of calculations from a model that was based on the optical Bloch equations and averaged over the Doppler profile. The calculations agree quite well with the measurements, especially when taking into account the fact that some experimental parameters were only estimated in the model. [Copyright &y& Elsevier]

We have studied the resonance fluorescence of a room-temperature rubidium vapor exited to the atomic 5P3/2 state (D2 line) by powerful single-frequency cw laser radiation (1.25 W/cm2) in the presence of a magnetic field. In these studies, the slow, linear scanning of the laser frequency across the hyperfine transitions of the D2 line is combined with a fast linear scanning of the applied magnetic field, which allows us to record frequency-dependent Hanle resonances from all the groups of hyperfine transitions including V- and Λ-type systems. Rate equations were used to simulate fluorescence signals for 85Rb due to circularly polarized exciting laser radiation with different mean frequency values and laser intensity values. The simulation show a dependence of the fluorescence on the magnetic field. The Doppler effect was taken into account by averaging the calculated signals over different velocity groups. Theoretical calculations give a width of the signal peak in good agreement with experiment. [ABSTRACT FROM AUTHOR]

We have studied the resonance fluorescence of a room-temperature rubidium vapor exited to the atomic 5P3/2 state (D2 line) by powerful single-frequency cw laser radiation (1.25 W/cm2) in the presence of a magnetic field. In these studies, the slow, linear scanning of the laser frequency across the hyperfine transitions of the D2 line is combined with a fast linear scanning of the applied magnetic field, which allows us to record frequency-dependent Hanle resonances from all the groups of hyperfine transitions including V- and Λ-type systems. Rate equations were used to simulate fluorescence signals for 85Rb due to circularly polarized exciting laser radiation with different mean frequency values and laser intensity values. The simulation show a dependence of the fluorescence on the magnetic field. The Doppler effect was taken into account by averaging the calculated signals over different velocity groups. Theoretical calculations give a width of the signal peak in good agreement with experiment. [ABSTRACT FROM AUTHOR]

Abstract: The pure electric field level-crossing of m F Zeeman sublevels of hyperfine F levels at two-step laser excitation is described theoretically and studied experimentally for the nD3/2 states in Cs with n =7, 9 and 10, by applying a diode laser in the first 6S1/2 →6P3/2 step and a diode or dye laser for the second 6P3/2 → nD3/2 step. Level-crossing resonance signals are observed in the nD3/2 →6P1/2 fluorescence. A theoretical model is presented to describe quantitatively the resonance signals by correlation analysis of the optical Bloch equations in the case when an atom simultaneously interacts with two laser fields in the presence of an external dc electric field. The simulations describe well the experimental signals. The tensor polarizabilities α2 (in ) are determined to be 7.45(20)×104 for the 7D3/2 state and 1.183(35)×106 for the 9D3/2 state; the electric field calibration is based on measurements of the 10D3/2 state, for which α2 is well established. The α2 value for the 7D3/2 state differs by ca. 15% from the existing experimentally measured value. [Copyright &y& Elsevier]

We present experimental data on the electric permanent dipole moments d(υ′,J′) and Λ splittings (q factors) in the quasidegenerate (3) 1Πe/f state of the NaCs molecule over a wide range of the vibrational (υ′) and rotational (J′) quantum numbers by using the combination of dc Stark mixing and electric radio frequency-optical double resonance methods. Within the experimental (3) 1Π state υ′ ranged from υ′=0 to 34, q values exhibited a pronounced decrease from 7.91×10-6 to 0.47×10-6 cm-1, while |d| values varied between 8.0 and 5.0 D. Experimental evaluation yielded small d values about 1 D for D(2) 1Π state υ′<3 levels. The experiment is supported by ab initio electronic structure calculations performed for the (1–3) 1Π states of NaCs by means of the many-body multipartitioning perturbation theory of potential energy curves, permanent dipole, and angular coupling matrix elements for the lowest singlet states. The predicted d values reproduce their experimental counterparts within the measurement errors while theoretical q factors reproduce the measured υ′ dependence being, however, systematically overestimated by ca. 1×10-6 cm-1. The present NaCs data are compared with those of the NaK and NaRb molecules. [ABSTRACT FROM AUTHOR]

The paper presents experimentally obtained permanent electric dipole moment values (μ) in electronically excited B [sup 1]Π and D [sup 1]Π states of [sup 23]Na[sup 85]Rb and [sup 23]Na[sup 87]Rb isotopomer molecules for a number of vibrational and rotational levels (v[sup ′],J[sup ′]). The method is based on measuring relative intensities of "forbidden" fluorescence lines appearing due to dc Stark effect induced e/f parity mixing for a particular (v[sup ′],J[sup ′])-level, combined with electric radio frequency-optical double resonance measurement of Λ-splitting energy Δ[sub e,f]. The measured D [sup 1]Π state μ values are close to 6 D, representing minor changes with the vibrational level v[sup ′] varying from 0 to 12 and J[sup ′] in the region between 7 and 50, while the measured B [sup 1]Π state μ values are about 3 D for v[sup ′]=4, 5 and 6. The X [sup 1]Σ[sup +], B [sup 1]Π, and D [sup 1]Π dipole moment functions μ(R) are calculated ab initio using the many body multipartitioning perturbation theory for explicit treatment of core-valence correlations. The theoretical and experimental dipole moment estimates are in a perfect agreement for the ground state and the D [sup 1]Π state, differing by 15%-25% for the B [sup 1]Π state. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Photodissociation of state-selected sodium molecules, Na[SUB2](X [SUP1]∑[SUP+,SUBg], ν") + hν → Na*[SUB2] (B [SUP1]Π[SUBu]) &raRR; Na*(3p[SUB3/2]) + Na(3s[SUB1/2]) has been studied theoretically and experimentally using a novel "field-free" ion imaging design. The experiment uses a supersonic Na/Na[SUB2] beam in combination with the stimulated Raman adiabatic passage technique to prepare Na[SUB2] molecules in selected rovibronic levels of the electronic ground state. The Na(3p[SUB3/2]) fragments are photoionized (or excited to high Rydberg states) in a permanently field-free reaction zone. The fragments enter the ion optics because of the flow velocity of the beam and are focused onto a position sensitive detector, which provides an energy resolution of about 50 meV. The measured anisotropic photofragment angular distributions reflect the alignment of the molecules prior to dissociation and are well explained by the anisotropic nature of the photodissociation by polarized laser light. The measured images show not only the expected relatively fast photodissociation fragments, but also the efficient formation of slow Na(3p[SUB3/2]) atoms. Fast and slow refer to the atomic velocity relative to the center of-mass of the dissociating molecule. The ratio of the numbers of slow atoms and fast photofragments is 0.16 and 0.22 for the dissociation of Na[SUB2] from levels ν" = 17 and ν" = 23, respectively. Several models are analyzed to explain the observations. Calculations show that the dramatic velocity redistribution is caused by radiation trapping: the excitation is efficiently radiatively transferred from the fast Na(3p) photofragments to the abundant Na(3s) atoms from the primary beam, whereby the hyperfine splitting of the 3s state must be taken into account. Analytical formulas describing this mechanism show a ratio of slow to fast Na(3p) atoms of 0.13 for ν" = 17 and 0.19 for ν" = 23, which is in very good agreement with the... [ABSTRACT FROM AUTHOR]

This paper reports the observation of the molecular fluorescence circularity under irradiation with linear polarized light. The phenomenon arises as a result of partial transformation from alignment of the ensemble of molecular angular momenta into orientation due to quadratic correction to Zeeman effect. Circularity rate up to 0.05 at magnetic field 0.4 T was registered in B 3Σu-(1u-)→X 3Σg-(1g-) fluorescence of 130Te2 molecules at angle π/4 with respect to Ê vector of linear polarized exciting light. Quadratic magnetic energy terms are associated with magnetic field induced ΔJ=±1 e/f mixing between 1u-∼1u+ and 1u-∼0u+ states. Circularity data fitting shows that the electronic part of Landé factor caused by 1u-∼0u+ interaction is equal to G± [bar_over_tilde:_approx._equal_to]gl<0u|Ja±|1u>+(gs-gl) <0u|S±|1u>[bar_over_tilde:_approx._equal_to]2.72. [ABSTRACT FROM AUTHOR]

We present systematic measurements of longitudinal relaxation rates (1/T1) of spin polarization in the ground state of the nitrogen-vacancy (NV-) color center in synthetic diamond as a function of NV- concentration and magnetic fieldB. NV- centers were created by irradiating a Type 1b single-crystal diamond along the [100] axis with 200 keV electrons from a transmission electron microscope with varying doses to achieve spots of different NV- center concentrations. Values of (1/T1) were measured for each spot as a function of B. [ABSTRACT FROM AUTHOR]

The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the Rb D line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ are used: an Rb cell with antirelaxation coating ( L ~ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field. [ABSTRACT FROM AUTHOR]

Abstract: We have implemented the so-called λ-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field B in the range of 2500−5000G (recently it was established that LZT is very convenient for the range of 10−2500G). Atoms are confined in a nanometric thin cell (NTC) with the thickness L = λ, where λ is the resonant wavelength 794nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on the B-field. Possible applications are described, such as magnetometers with nanometric local spatial resolution and tunable atomic frequency references. [Copyright &y& Elsevier]

It has been experimentally demonstrated that the use of the effect of significant narrowing of the fluorescence spectrum from a nanocell that contains a column of atomic Rb vapor with a thickness of L = 0.5λ (where λ = 794 nm is the wavelength of laser radiation, whose frequency is resonant with the atomic transition of the D1 line of Rb) and the application of narrowband diode lasers allow the spectral separation and investigation of changes in probabilities of optical atomic transitions between levels of the hyperfine structure of the D1 line of 87Rb and 85Rb atoms in external magnetic fields of 10–2500 Gs (for example, for one of transitions, the probability increases ∼17 times). Small column thicknesses (∼390 nm) allow the application of permanent magnets, which facilitates significantly the creation of strong magnetic fields. Experimental results are in a good agreement with the theoretical values. The advantages of this method over other existing methods are noted. The results obtained show that a magnetometer with a local spatial resolution of ∼390 nm can be created based on a nanocell with the column thickness L = 0.5λ. This result is important for mapping strongly inhomogeneous magnetic fields. [ABSTRACT FROM AUTHOR]

An extremely thin cell with a wedge gap was developed that makes it possible to form a column of Rb atom vapor with thickness in the range from 100 to 600 nm. It is experimentally shown that the use of this cell, along with commercially available diode lasers, allows one to spectrally resolve individual transitions between the Zeeman sublevels of the hyperfine structure of the [sup 87]RbD[sub 1] line (transitions F[sub g] = 1, 2→F[sub e] = 1, 2) in the resonance fluorescence spectrum in the presence of an external magnetic field (B≈200 G). This makes it possible to realize systems consisting of nondegenerate atomic levels. For comparison, it is shown that transitions between the Zeeman sublevels in the fluorescence spectrum obtained with the aid of a conventional cell (1–10 cm long) in an external magnetic field with B∼200 G remain completely masked by the Doppler-broadened profile. The results obtained can be used for the creation of a simple magnetometer based on an extremely thin cell with Rb vapor for the measurement of magnetic fields with a submicron local spatial resolution. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

We describe the so-called λ-Zeeman method to investigate individual hyperfine transitions between Zeeman sublevels of atoms in an external magnetic field of 0.1 mT–0.25 T. Atoms are confined in a nanocell with thickness L=λ, where λ is the resonant wavelength (794 or 780 nm for D1 or D2 line, respectively, of Rb). Narrow resonances in the transmission spectrum of the nanocell are split into several components in a magnetic field; their frequency positions and transition probabilities depend on the B field. Possible applications are described, such as magnetometers with nanometric spatial resolution and tunable atomic frequency references. [ABSTRACT FROM AUTHOR]