Theory of the optical spectrum of Na2 on 4He droplets: effects of the zero-point energy of the nearest atoms

Hizhnyakov, V.; Tehver, I.; Benedek, G.

doi:10.1140/epjb/e2009-00277-1

Cited by 12 publications

(11 citation statements)

References 22 publications

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“…The LiCa molecule is more strongly bound than the alkali triplet molecules, but weaker than, for example, the sodium singlet dimers (5942.6880(49) cm –1 ), which have been investigated on the helium droplet surface extensively . The observed peak structure is characteristic for surface located molecules ,,, with strongly coupled vibrational motion to the surface of the helium droplet. Because of the similarities between Li– and Ca–helium interaction energies and the similarities between the spectra of surface bound alkali triplet molecules and the LiCa spectra we expect the LiCa molecule to reside on the surface of the helium droplet.…”

Section: Results and Discussionmentioning

confidence: 99%

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Spectroscopy of Cold LiCa Molecules Formed on Helium Nanodroplets

et al. 2013

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We report on the formation of mixed alkali–alkaline earth molecules (LiCa) on helium nanodroplets and present a comprehensive experimental and theoretical study of the ground and excited states of LiCa. Resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) spectroscopy and laser induced fluorescence (LIF) spectroscopy were used for the experimental investigation of LiCa from 15000 to 25500 cm–1. The 42Σ+ and 32Π states show a vibrational structure accompanied by distinct phonon wings, which allows us to determine molecular parameters as well as to study the interaction of the molecule with the helium droplet. Higher excited states (42Π, 52Σ+, 52Π, and 62Σ+) are not vibrationally resolved and vibronic transitions start to overlap. The experimental spectrum is well reproduced by high-level ab initio calculations. By using a multireference configuration interaction (MRCI) approach, we calculated the 19 lowest lying potential energy curves (PECs) of the LiCa molecule. On the basis of these calculations, we could identify previously unobserved transitions. Our results demonstrate that the helium droplet isolation approach is a powerful method for the characterization of tailor-made alkali–alkaline earth molecules. In this way, important contributions can be made to the search for optimal pathways toward the creation of ultracold alkali–alkaline earth ground state molecules from the corresponding atomic species. Furthermore, a test for PECs calculated by ab initio methods is provided.

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Section: Results and Discussionmentioning

confidence: 99%

“… 35 Furthermore, the structure of the broadened vibronic transition in the recorded spectrum gives insights into the interaction between molecule and helium droplet. 28 , 36 …”

Section: Introductionmentioning

confidence: 99%

Spectroscopy of Cold LiCa Molecules Formed on Helium Nanodroplets

et al. 2013

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“…This peculiar difference was theoretically analyzed by Tehver, Hizhnyakov, and Benedek. 54 , 55 The gapless appearance of a phonon-wing was attributed to a stronger coupling of vibrational motion of the dimer molecule to excitation modes of the helium droplet.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopy of Lithium Atoms and Molecules on Helium Nanodroplets

et al. 2013

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We report on the spectroscopic investigation of lithium atoms and lithium dimers in their triplet manifold on the surface of helium nanodroplets (HeN). We present the excitation spectrum of the 3p ← 2s and 3d ← 2s two-photon transitions for single Li atoms on HeN. The atoms are excited from the 2S(Σ) ground state into Δ, Π, and Σ pseudodiatomic molecular substates. Excitation spectra are recorded by resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) mass spectroscopy, which allows an investigation of the exciplex (Li*–Hem, m = 1–3) formation process in the Li–HeN system. Electronic states are shifted and broadened with respect to free atom states, which is explained within the pseudodiatomic model. The assignment is assisted by theoretical calculations, which are based on the Orsay–Trento density functional where the interaction between the helium droplet and the lithium atom is introduced by a pairwise additive approach. When a droplet is doped with more than one alkali atom, the fragility of the alkali–HeN systems leads preferably to the formation of high-spin molecules on the droplets. We use this property of helium nanodroplets for the preparation of Li dimers in their triplet ground state (13Σu+). The excitation spectrum of the 23Πg(ν′ = 0–11) ← 13Σu+(ν″ = 0) transition is presented. The interaction between the molecule and the droplet manifests in a broadening of the transitions with a characteristic asymmetric form. The broadening extends to the blue side of each vibronic level, which is caused by the simultaneous excitation of the molecule and vibrations of the droplet (phonons). The two isotopes of Li form 6Li2 and 7Li2 as well as isotope mixed 6Li7Li molecules on the droplet surface. By using REMPI-TOF mass spectroscopy, isotope-dependent effects could be studied.

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“…Experimentally, the 4 2 S + ' X 2 S + transition is vibrationally resolved and each band shows a characteristic lambda-shaped peak form. 47,48 All other states denoted in the spectrum could not be vibrationally resolved and appear as broadened, featureless and partly overlapped structures. The assignment of the transitions is based on a comparison of experimental and theoretical spectra, as will be shown in detail in the following.…”

Section: Excitation Spectrummentioning

confidence: 97%

Characterization of RbSr molecules: spectral analysis on helium droplets

Krois

Lackner

Pototschnig

et al. 2014

Phys. Chem. Chem. Phys.

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We report an experimental investigation of RbSr molecules attached to helium nanodroplets. The molecules are prepared on the surface of helium droplets by utilizing a sequential pickup scheme. We provide a detailed analysis of the excitation spectrum in the wavelength range 11,600-23,000 cm(-1). The spectrum has been recorded by resonance enhanced multi-photon ionization time-of-flight spectroscopy. The inherent mass sensitivity of the method allows for an unraveling of the RbSr spectrum, which is influenced by Rb and Sr dimer contributions, because of the proximity of their respective isotopologues. In addition, the vibrationally resolved 4(2)Σ(+) band was investigated using laser induced fluorescence spectroscopy. The vibronic transitions exhibit a lambda-shaped peak form, which is characteristic of excitations on helium droplets and indicative of strong coupling of the molecule to the superfluid helium environment. Furthermore, the vibrationally resolved 4(2)Σ(+) state enables the determination of molecular parameters, which are in excellent agreement with previously measured dispersed fluorescence spectra, originating from bare RbSr molecules. The assignment of recorded transitions is based on calculated transition dipole moments and potential energy curves. The theoretical results allow for the identification of transitions from the vibronic X(2)Σ(+) ground state to the 2(2)Π, 3(2)Σ(+), 4(2)Σ(+), 3(2)Π, 4(2)Π and 6(2)Σ(+) states. The detailed investigation of RbSr on helium droplets provides a solid basis for further high resolution gas phase studies of this diatomic molecule that holds promise in the area of cold molecular physics.

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Theory of the optical spectrum of Na2 on 4He droplets: effects of the zero-point energy of the nearest atoms

Cited by 12 publications

References 22 publications

Spectroscopy of Cold LiCa Molecules Formed on Helium Nanodroplets

Spectroscopy of Cold LiCa Molecules Formed on Helium Nanodroplets

Spectroscopy of Lithium Atoms and Molecules on Helium Nanodroplets

Characterization of RbSr molecules: spectral analysis on helium droplets

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