Molecular Beam Magnetic Resonance in Doped Helium Nanodroplets. A Setup for Optically Detected ESR/NMR in the Presence of Unresolved Zeeman Splittings

Koch, Markus; Lanzersdorfer, Johannes; Callegari, Carlo; Muenter, J. S.; Ernst, Wolfgang

doi:10.1021/jp9041827

Cited by 18 publications

(31 citation statements)

References 61 publications

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“…Recently, a new spectroscopic technique has been developed that allows for a detection of electron spin resonance (ESR) transitions in doped helium nanodroplets 1, 2. It has the potential to monitor interactions between dopants sitting on the surface and inside a helium droplet of a given size 3.…”

Section: Introductionmentioning

confidence: 99%

Shifts in the ESR Spectra of Alkali‐Metal Atoms (Li, Na, K, Rb) on Helium Nanodroplets

et al. 2012

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He-droplet-induced changes of the hyperfine structure constants of alkali-metal atoms are investigated by a combination of relativistically corrected ab initio methods with a simulation of the helium density distribution based on He density functional theory. Starting from an accurate description of the variation of the hyperfine structure constant in the M–He diatomic systems (M=Li, Na, K, Rb) as a function of the interatomic distance we simulate the shifts induced by droplets of up to 10 000 4He atoms. All theoretical predictions for the relative shifts in the isotropic hyperfine coupling constants of the alkali-metal atoms attached to helium droplets of different size are then tied to a single, experimentally derived parameter of Rb.

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Section: Introductionmentioning

confidence: 99%

Shifts in the ESR Spectra of Alkali‐Metal Atoms (Li, Na, K, Rb) on Helium Nanodroplets

et al. 2012

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“…In the Cr + signal in Fig. These spectral characteristics are comparable to transitions of heavier alkali metal atoms that reside in a surface dimple, 27,35,46 which is a first indication for the surface location of the a 5 S 2 atom (others will follow). Considering the detailed Cr + scan (Fig.…”

Section: Separation To a Surface Located A 5 S 2 And A Solvated A 7 Smentioning

confidence: 81%

Photoinduced molecular dissociation and photoinduced recombination mediated by superfluid helium nanodroplets

Kautsch

Koch

Ernst

2015

Phys. Chem. Chem. Phys.

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We have investigated photoinduced chemical reaction dynamics of cold, isolated Cr2 molecules in helium nanodroplets (HeN), exploiting the quantum state specific spatial separation of solvated and surface locations on the droplet. The molecules are excited to achieve dissociation to a ground state (a(7)S3) and a metastable state (a(5)S2) atom. State specific spatial separation, in combination with efficient translational cooling to avoid ejection, causes the ground state atom to be solvated inside the droplet while the metastable atom migrates to the surface. A barrier between the two reactants formed by the HeN prevents recombination. We apply a resonance-enhanced multiphoton ionization scheme including the y(5)P°(1,2,3) <-- a(5)S(2) transition of the surface atom as well as a two-laser scheme including the y(7)P°(2,3,4) <-- a(7)S(3) transition of the solvated atom in order to verify the locations and separation of the dissociation products. Furthermore, ionization of the a(5)S2 surface atom triggers solvation followed by geminate recombination with the a(7)S3 atom, which is verified by the detection of Cr2(+) molecular ions. For small Cr clusters, our results indicate that they may be composed of chromium dimers that exhibit the same dissociation behavior.

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“…A complete description of the experimental setup is given elsewhere [31]. In brief, He droplets are produced via supersonic expansion of grade-6 He gas through a cold nozzle into vacuum (nozzle diameter 5 µm, T = 12.5-23 K, stagnation pressure 50 bar, mean droplet sizeN ≈ 1000-15000 He atoms).…”

Section: Methodsmentioning

confidence: 99%

“…The laser is tuned to the wavelength with the most efficient spin polarization and spin probe action (12601 cm −1 for Rb, 12993 cm −1 for K) [31]. For Rb this is roughly the maximum of the droplet broadened line of the D 1 transition (5 2 P 1/2 ←5 2 S 1/2 ), whereas for K the optimum spin polarization/probe action is at lower excitation energy than the center of the droplet broadened D 1 line (4 2 P 1/2 ←4 2 S 1/2 ) [31].…”

Section: Methodsmentioning

confidence: 99%

“…These have culminated in the successful implementation of optically detected magnetic resonance (ODMR), and we have been able to recently report the first observation of hyperfine-resolved electron spin resonance (ESR) spectra of K and Rb on the surface of He nanodroplets [30,31], with such high resolution that shifts could be followed as a function of droplet size for 85 Rb atoms, despite the fact that they amount to few parts per million only. Previously electron-and nuclear-spin spectroscopy of alkalimetal atoms were performed in bulk superfluid and solid He matrices [32][33][34] at lower experimental accuracy, so that the effect of the He, although larger, was hardly quantifiable.…”

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Alkali-metal electron spin density shift induced by a helium nanodroplet

2010

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. Alkali-metal electron spin density shift induced by a helium nanodroplet. Molecular Physics, Taylor Francis, 2010, 108 (07-09) Helium (He) nanodroplets provide a cold and virtually unperturbing environment for the study of weakly bound molecules and van der Waals aggregates. High resolution microwave spectroscopy and the detection of electron spin transitions in doped He droplets have recently become possible. Measurements of hyperfine-resolved electron spin resonance in potassium ( 39 K) and rubidium ( 85 Rb) atoms on the surface of He droplets show small line shifts relative to the bare atoms. These shifts were recorded for all 2I + 1 components (I is the nuclear spin) of a transition at high accuracy for He droplets ranging in size from 1000 to 15000 He atoms. Evaluation of the spectra yields the influence of the He environment on the electron spin density at the alkali-metal nucleus. A semiempirical model is presented that shows good qualitative agreement with the measured droplet size dependent increase of Fermi contact interaction at the nuclei of dopant K and Rb.

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Molecular Beam Magnetic Resonance in Doped Helium Nanodroplets. A Setup for Optically Detected ESR/NMR in the Presence of Unresolved Zeeman Splittings

Cited by 18 publications

References 61 publications

Shifts in the ESR Spectra of Alkali‐Metal Atoms (Li, Na, K, Rb) on Helium Nanodroplets

Shifts in the ESR Spectra of Alkali‐Metal Atoms (Li, Na, K, Rb) on Helium Nanodroplets

Photoinduced molecular dissociation and photoinduced recombination mediated by superfluid helium nanodroplets

Alkali-metal electron spin density shift induced by a helium nanodroplet

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