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  • 1
    Electronic Resource
    Electronic Resource
    Lifetimes and transition dipole moment functions of NaK low lying singlet states: Empirical and ab initio approach (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 6725-6735 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The paper presents experimental D 1∏ state lifetime τv′J′ data and develops empirical and ab initio approaches concerning D 1∏ and B 1∏ lifetimes, as well as D 1∏–X 1∑+, B 1∏–X 1∑+ and D 1∏–A 1∑+ transition dipole moment functions μ(R) of the NaK molecule. Experimental D 1∏(v′,J′) state τv′J′ values for v′ varying from 1 to 22 have been obtained from experimentally measured electric radio frequency-optical double resonance (rf-ODR) signal contours. The rf-ODR signals have been produced by D 1∏←X 1∑+ laser induced optical transition and rf field (1–900 MHz) induced e–f transition within the D 1∏(v′,J′) level. The possibility to determine empirical absolute μ(R) function in a wide R range from experimental τv′J′ dependence on v′ and J′ has been demonstrated; such an approach has been applied to obtain μ(R) for the B 1∏–X 1∑+ transition on which relative intensity data are absent. The empirical D 1∏–X 1∑+μ(R) function has been considerably improved by simultaneous fitting of relative intensity and lifetime data implicitly accounting for the J′ dependence of measured lifetime values. The finite-field technique combined with the many-body multipartitioning perturbation theory was used for ab initio all-electron transition moment calculations. This approach appeared to be adequate to compute reliable μ(R) functions due to a proper description of core-valence correlations. As a result, excellent agreement between ab initio and empirical B 1∏–X 1∑+ and D 1∏–X 1∑+ transition dipole moment functions has been achieved. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.477350
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  • 2
    Electronic Resource
    Electronic Resource
    NaK D1Π electric dipole moment measurement by Stark level crossing and e–f mixing spectroscopy (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 2195-2204 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The paper presents the first permanent electric dipole moment dp measurements for NaK D1Π state rovibronic levels. Two different methods were applied to obtain dp values. Stark effect induced level crossing registered as the changes of fluorescence linear polarization P(E) with external electric field E yielded from one fit both the electric dipole moment value and the Λ-doubling splitting between e,f substates of an individual rotational state. Another method consisted of obtaining the ratio ΔefJ/dp from E-dependence of the forbidden line appearing in fluorescence as a result of e–f Stark mixing, along with direct ΔefJ measurement by RF – optical double resonance. The respective dipole moment values obtained are 5.9 – 6.4 D for the state v=7, J=23, as well as 4.5 – 4.8 D for v=12, J=7, the typical errors being ca. 12%–20%. The dp value for the latter state reflects dp diminution expected due to the admixture of the d3Π state caused by intramolecular interaction. Signal simulation and data fitting have been accomplished using direct Hamiltonian diagonalization accounting for Stark interaction within rotational states J±ΔJ,ΔJ=0,1 and 2 in the initial, excited and final state. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473145
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  • 3
    Electronic Resource
    Electronic Resource
    Permanent electric dipoles in B 1Π and D 1Π states of NaRb: Experiment and theory (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4896-4900 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The paper presents experimentally obtained permanent electric dipole moment values (μ) in electronically excited B 1Π and D 1Π states of 23Na85Rb and 23Na87Rb isotopomer molecules for a number of vibrational and rotational levels (v′,J′). 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′,J′)-level, combined with electric radio frequency–optical double resonance measurement of Λ-splitting energy Δe,f. The measured D 1Π state μ values are close to 6 D, representing minor changes with the vibrational level v′ varying from 0 to 12 and J′ in the region between 7 and 50, while the measured B 1Π state μ values are about 3 D for v′=4, 5 and 6. The X 1Σ+, B 1Π, and D 1Π 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 1Π state, differing by 15%–25% for the B 1Π state. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1289249
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  • 4
    Electronic Resource
    Electronic Resource
    Magnetic field induced alignment–orientation conversion: Nonlinear energy shift and predissociation in Te2 B1u state (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 37-49 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: 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(minus-plus)1−M or in relaxation of coherence ΓMM±1≠Γ−M(minus-plus)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|Hˆpm|Ω=1)≡G±=2.7, as well as the natural Cvhet=±6 s−1/2 and the magnetic αvhet=(minus-plus)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 in Zeeman energy shift. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471833
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  • 5
    Electronic Resource
    Electronic Resource
    Alignment-orientation conversion by quadratic Zeeman effect: Analysis and observation for Te2 (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 5748-5753 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: 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 Eˆ 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± (approximately-equal-to)gl〈0u||Ja±||1u〉+(gs−gl) 〈0u||S±||1u〉(approximately-equal-to)2.72.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465925
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  • 6
    Electronic Resource
    Electronic Resource
    Emergence of circularity at linear polarized excitation of molecules (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 5742-5747 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: 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 ωMM′ when ωMM±1≠ω−M≠1−M and ωMM′ 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 1∑ state molecules with J=10 assuming a quadratic Stark effect in a homogeneous external electric field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466246
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  • 7
    Electronic Resource
    Electronic Resource
    Separation of quadratic and linear external field effects in high J quantum beats (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 5559-5565 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: 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(very-much-greater-than)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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467343
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  • 8
    Electronic Resource
    Electronic Resource
    Nonlinear Hanle effect in Cs vapor under strong laser excitation (2002)
    Springer
    The European physical journal 21 (2002), S. 63-71 
    Details
    ISSN: 1434-6079
    Keywords: PACS. 32.80.Bx Level crossing and optical pumping – 32.80.Qk Coherent control of atomic interactions with photons – 42.50.Gy Effects of atomic coherence on propagation, absorption, and amplification of light
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: We report results of a theoretical and experimental study of the ground state nonlinear Hanle effect under strong laser excitation. It is shown that besides the well-known zero-magnetic field suppression of absorption on F g = F→F e = F - 1 transitions caused by population trapping, an optical pumping induced enhanced absorption occurs on F g = F→F e = F + 1 transitions for small B-fields. The latter effect becomes more pronounced for high F values. The experiment with atomic vapor of Cs (D2 line, F g = 4) confirms an increase of the spectrally unresolved fluorescence yield at zero magnetic field and 600 mW/cm2 laser intensity by 9% or 42%, when excitation occurs with linearly or circularly polarized light, respectively. The results of the experiment agree with numerical simulation studies using equations of motion for a density matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjd/e2002-00178-y
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  • 9
    Electronic Resource
    Electronic Resource
    Alignment-orientation conversion in molecules in an external magnetic field caused by a hyperfine structure (2000)
    Springer
    The European physical journal 11 (2000), S. 91-97 
    Details
    ISSN: 1434-6079
    Keywords: PACS. 32.60.+i Zeeman and Stark effects - 32.10.Fn Fine and hyperfine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The paper presents a discussion on the problem of alignment-orientation conversion in an excited state of molecules. It is shown that a rather strong alignment-orientation conversion effect in the excited molecular state can be caused by a joint action of an external magnetic field and hyperfine interaction. The orientation thus created is transverse, i.e. perpendicular to the direction of the external magnetic field. The magnitude of this effect is analyzed as dependent on molecular parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100530070108
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  • 10
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    Can a Quantum Nondemolition Measurement Improve the Sensitivity of an Atomic Magnetometer? (2004)
    American Physical Society
    Details
    Publication Date: 2004-10-19
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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