Non-adiabatic mass-correction functions and rovibrational states of 4He2+ (X 2Σu+)

Mátyus, Edit

doi:10.1063/1.5050403

Cited by 23 publications

(32 citation statements)

References 49 publications

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“…, 19 rotational levels [25][26][27] of the ground vibronic level of 4 He 2 + * merkt@xuv.phys.chem.ethz.ch and their spin-rotational splitting [28], determined from the analysis of high Rydberg states of He 2 . Both the spin-rotational splittings and the rotational term values revealed discrepancies with the values obtained by the latest calculations [14,24], although significant progress in the calculation of nonadiabatic corrections could be achieved very recently [29].…”

Section: Introductionmentioning

confidence: 66%

Fundamental vibration frequency and rotational structure of the first excited vibrational level of the molecular helium ion (He2+)

Jansen

Semeria

Merkt

2018

The Journal of Chemical Physics

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The term values of rotational levels of the first excited vibrational state of the electronic ground state of He2 + with rotational quantum number N + ≤ 13 have been determined with an accuracy of 1.2 × 10 −3 cm −1 (∼35 MHz) by MQDT-assisted Rydberg spectroscopy of metastable He2. Comparison of the experimental term values with the most accurate ab initio results for He2 + available in the literature [W.-C. Tung, M. Pavanello, and L. Adamowicz, J. Chem. Phys. 136, 104309 (2012)] reveals inconsistencies between theoretical and experimental results that increase with increasing rotational quantum number. The fundamental vibrational wavenumber of He2 + was determined to be 1628.3832(12) cm −1 by fitting effective molecular constants to the obtained term values.

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Section: Introductionmentioning

confidence: 66%

Fundamental vibration frequency and rotational structure of the first excited vibrational level of the molecular helium ion (He2+)

Jansen

Semeria

Merkt

2018

The Journal of Chemical Physics

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“…For the ionization energies of heavy, multi-electron systems like K and Cs, the achievable experimental accuracy currently exceeds the accuracy of theoretical ab-initio calculations by orders of magnitude. However, apply- ing similar techniques to lighter systems, such as H 2 [3], provides a test bed for the development of theoretical methods [66][67][68][69] and might allow for improved determinations of fundamental constants [9,66]. In addition to the ionization energy, we obtained energy dependent quantum defects for the s, p, d, f and g series in 39 K. This set of quantum defects in 39 K improves previous work [14][15][16] and can be used, e.g., in the calculation of Rydberg-Rydberg interaction potentials [5,6] and of the energy-level structure of long-range Rydberg molecules [4,70].…”

Section: Discussionmentioning

confidence: 99%

Precision measurement of the ionization energy and quantum defects ofK39i

et al. 2019

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We present absolute-frequency measurements in ultracold 39 K samples of the transitions from the 4s 1/2 ground state to np 1/2 and np 3/2 Rydberg states. A global nonlinear regression of the np 1/2 and np 3/2 term values yields an improved wave number of 35 009.813 971 0(22)sys(3)stat cm −1 for the first ionization threshold of 39 K and the quantum defects of the np 1/2 and np 3/2 series. In addition, we report the frequencies of selected one-photon transitions n s 1/2 ← np 3/2 , n dj ← np 3/2 , n f j ← ndj and n g j ← nfj and two-photon transitions nf j ← npj determined by millimeter-wave spectroscopy, where j is the total angular momentum quantum number. By combining the results from the laser and millimeter-wave spectroscopic experiments, we obtain improved values for the quantum defects of the s 1/2 , d 3/2 , d 5/2 , fj and gj states. For the dj series, the inverted fine structure was confirmed for n ≥ 32. The fine-structure splitting of the f series is less than 100 kHz at n = 31, significantly smaller than the hydrogenic splitting, and the fine structure of the g series is regular for n ≥ 30, with a fine-structure splitting compatible with the hydrogenic prediction. From the measured quantum defects of the f and g series we derive an estimate for the static dipole α d and quadrupole αq polarizabilities of the K + ion core. Additionally, the hyperfine splitting of the 4s 1/2 ground state of 39 K was determined to be 461.719 700(5) MHz using radio-frequency spectroscopy and Ramsey-type interferometry.

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“…Earlier work in which the mass-correction terms were computed for a single electronic state, e.g., Refs. [37,38], can be generalized for a multi-state band, so numerical applications will probably follow this theoretical work in the near future.…”

Section: Introductionmentioning

confidence: 99%

Effective non-adiabatic Hamiltonians for the quantum nuclear motion over coupled electronic states

Mátyus

Teufel

2019

The Journal of Chemical Physics

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The quantum mechanical motion of the atomic nuclei is considered over a single-or a multidimensional subspace of electronic states which is separated by a gap from the rest of the electronic spectrum over the relevant range of nuclear configurations. The electron-nucleus Hamiltonian is block-diagonalized up to O(ε n+1 ) through a unitary transformation of the electronic subspace and the corresponding nth-order effective Hamiltonian is derived for the quantum nuclear motion.Explicit but general formulae are given for the second-and the third-order corrections. As a special case, the second-order Hamiltonian corresponding to an isolated electronic state is recovered which contains the coordinate-dependent mass-correction terms in the nuclear kinetic energy operator. For a multi-dimensional, explicitly coupled electronic band, the second-order Hamiltonian contains the usual BO terms and non-adiabatic corrections but generalized mass-correction terms appear as well.These, earlier neglected terms, perturbatively account for the outlying (discrete and continuous) electronic states not included in the explicitly coupled electronic subspace. * Electronic address: matyus@chem.elte.hu † Electronic address: stefan.teufel@uni-tuebingen.de

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Non-adiabatic mass-correction functions and rovibrational states of 4He2+ (X 2Σu+)

Cited by 23 publications

References 49 publications

Fundamental vibration frequency and rotational structure of the first excited vibrational level of the molecular helium ion (He2+)

Fundamental vibration frequency and rotational structure of the first excited vibrational level of the molecular helium ion (He2+)

Precision measurement of the ionization energy and quantum defects ofK39i

Effective non-adiabatic Hamiltonians for the quantum nuclear motion over coupled electronic states

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