Detachment of metastable helium molecules from helium nanodroplets

Yurgenson, S. V.; Hu, Chih-Ching; Kim, C.; Northby, J. A.

doi:10.1007/s100530050417

Cited by 19 publications

(14 citation statements)

References 32 publications

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“…34,35,[107][108][109][110][111][112][113][114] The repulsive nature of the interaction of these species with the liquid helium results in a very similar behavior to that observed for alkali atoms or dimers. Photoionization of pure and doped helium droplets have been studied in Ref.…”

Section: Intrinsic He Impuritiesmentioning

confidence: 55%

“…Onaxis or off-axis surface ionization detectors, well known for their high quantum efficiency, have been successfully used for the spectroscopy of alkali atoms 37 and He 2 * molecules. 34,35 Upon excitation these species detach from the droplet thus giving rise to a decrease of the ion current for an on-axis configuration. Upon irradiation with less than 100 mW of laser power, a depletion of up to 50% can easily be achieved with Na atoms attached to He droplets.…”

Section: Experimental Aspectsmentioning

confidence: 99%

“…103 Some of the He 2 * species formed upon electron impact were found to remain captured in a shallow potential minimum at the surface of the droplet. 35 From a variety of excited species, only metastable He 2 *(a 3 ⌺ u ϩ ) survives. Like Na 2 molecules, these species are only weakly bound to the surface of the droplet and detach spontaneously, 107,108,112,114 or upon laser excitation of the He 2 *(c 3 ⌺ g ϩ ←a 3 ⌺ u ϩ ) and molecules on the surface of the helium droplets is found to be highly nonthermal as only the high rotational states ͑N ϭ11-29, peaked at Nϭ17͒, together with the lowest Nϭ1 state are populated while lines from Nϭ3 -9 are missing.…”

Section: Intrinsic He Impuritiesmentioning

confidence: 99%

See 2 more Smart Citations

Electronic spectroscopy in He droplets

Stienkemeier

Vilesov

2001

The Journal of Chemical Physics

228

288

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Articles you may be interested inThe structure of mixed 3He-4He droplets doped with OCS: A density functional approachThe ethyl radical in superfluid helium nanodroplets: Rovibrational spectroscopy and ab initio computationsThe vibrational and rotational dynamics of acetylene solvated in superfluid helium nanodroplets Recent experiments on the electronic spectroscopy of atoms, clusters, and organic molecules embedded in helium nanodroplets are reviewed. Electronic transitions imply a larger degree of distortion of the helium environment as compared to vibrational and rotational excitations. Thus new phenomena arise such as the appearance of side bands in the spectra, which are due to the excitation of helium collective vibrations, large changes of the effective molecular rotational constants and even the expulsion of an atom ͑or molecule͒ from the cluster upon excitation. These features make it possible to probe the helium environment and its interactions with molecular chromophores on the atomic scale. Real-time studies of the manifestations of superfluidity and of chemical processes in the droplets via femtosecond excitation techniques, provide a new perspective to this field. The considerable amount of data available so far shows the large potential of helium droplets for isolation and spectroscopy of large molecules and clusters. The low temperature and the high spectral resolution achievable because of the relative homogeneity of this medium, are instrumental for separating solvation effects that are obscured by the presence of much larger fluctuations in more classical environments. Hence, electronic and geometrical structures of even large entities become accessible.

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Section: Intrinsic He Impuritiesmentioning

confidence: 55%

Section: Experimental Aspectsmentioning

confidence: 99%

Section: Intrinsic He Impuritiesmentioning

confidence: 99%

See 1 more Smart Citation

Electronic spectroscopy in He droplets

Stienkemeier

Vilesov

2001

The Journal of Chemical Physics

228

288

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“…It is more likely that the formation process accounts for the temperature of 350 K. This means that in principle a He molecule could have any energy between 30 mV (0.4 K) and the excess energy of 2.79 eV. We ought to mention that other groups also observe unusual high rotational temperatures when exciting molecules at the surface of 4 He clusters [23,24].…”

mentioning

confidence: 99%

Bubble Formation and Decay inH3eandH

et al. 2002

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The energy transfer in 3He and 4He clusters electronically excited by monochromatic synchrotron radiation is investigated by luminescence spectroscopy. Depending on the cluster size and the isotopic constitution, either sharp, broadened, or shifted emission bands of single He molecules are observed. The spectral features show that He molecules emit light either within a bubble inside the cluster or in the vacuum after desorption from the cluster. From the luminescence intensity, the cluster diameter, and the radiative lifetime, an average velocity of approximately 7 m/s of bubbles in 4He clusters could be deduced. In the nonsuperfluid 3He clusters this velocity was observed to be significantly lower.

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“…Helium clusters and droplets have been excited with electrons [40][41][42][43][44][45] and with VUV radiation [2,7,11,[46][47][48][49][50][51][52][53][54][55][56][57], including high harmonic generation [58][59][60]. More recently, intense VUV radiation from free electron laser light sources has also been employed [61,62].…”

Section: Introductionmentioning

confidence: 99%

Atomic fluorescence emitted from a corona discharge in helium above and below saturated vapour pressure

et al. 2018

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Abstract.A new apparatus was constructed to investigate the visible and near infrared fluorescence spectroscopy of electronically excited helium over a wide range of pressures and temperatures, covering both the gaseous and liquid phases. To achieve sufficient throughput, increased sensitivity was established by employing a micro-discharge cell and a high performance lens system that allows for a large collection solid angle. With this set-up, several thousand spectra were recorded. The atomic 3s1 S → 2p 1 P and 3s 3 S → 2p 3 P atomic transitions showed line shifts, spectral broadening and intensity changes that were dependent in magnitude on pressure, temperature and thermodynamic phase. While in the gas phase the lines showed little dependency on the discharge cell temperature, the opposite was observed for the liquid phase, suggesting that a significant number of atoms were solvated. Triplet lines were up to a factor of 50 times stronger in intensity than the singlet lines, depending on pressure. When taking the particle density into account, this effect was stronger in the gas phase than in the liquid phase of helium. This was attributed to the recombination of He2 + , He3 + and He4 + with electrons, which is facilitated in the gas phase because of the significantly higher mobility.

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Detachment of metastable helium molecules from helium nanodroplets

Cited by 19 publications

References 32 publications

Electronic spectroscopy in He droplets

Electronic spectroscopy in He droplets

Bubble Formation and Decay inH3eandH

Atomic fluorescence emitted from a corona discharge in helium above and below saturated vapour pressure

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