Fano resonances in chromium photoionization spectra after photoinduced ejection from a superfluid helium nanodroplet

Kautsch, Andreas; Hasewend, Matthias; Koch, Markus; Ernst, Wolfgang

doi:10.1103/physreva.86.033428

Cited by 13 publications

(72 citation statements)

References 22 publications

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“…The broad excitation band agrees with our former photoionization (PI) experiment. 7 Compared to free atom transitions, a blue shift of approximately 300 cm –1 is measured. Similar, but much stronger, shifts were observed for Cr dopants in matrixes (Ar, Kr) with up to 1400 cm –1 .…”

Section: Results and Discussionmentioning

confidence: 95%

Electronic Relaxation after Resonant Laser Excitation of Cr in Superfluid Helium Nanodroplets

2013

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Chromium (Cr) atoms embedded into helium nanodroplets (HeN) are ejected from the droplets upon photoexcitation. During ejection they undergo electronic relaxation resulting in bare Cr atoms in various excited states. In a study of the relaxation process we present absorption spectra observed via laser induced fluorescence and beam depletion as well as dispersed fluorescence spectra and time-resolved fluorescence measurements. Broad and shifted absorption structures were found for the strong z7P° ← a7S3 and y7P° ← a7S3 excitations from the ground state. Emission lines are, in contrast, very narrow, which indicates that fluorescence is obtained from bare excited Cr atoms after ejection. Upon excitation into the y7P2,3,4° states we observed fluorescence from y7P2°, z5P1,2,3°, and z7P2,3,4°, indicating that these states are populated by electronic relaxation during the ejection processes. Relative population ratios are obtained from the intensities of individual spectral lines. Excitation into the z7P2,3,4° states resulted in fluorescence only from z7P2°. Estimates of the time duration of the ejection process are obtained from time-resolved measurements.

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Section: Results and Discussionmentioning

confidence: 95%

Electronic Relaxation after Resonant Laser Excitation of Cr in Superfluid Helium Nanodroplets

2013

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“…23 Bare atom ground state transitions are indicated by triangles. 37 The sharp lines can be assigned to transitions of bare, excited atoms to autoionizing states.…”

Section: Resultsmentioning

confidence: 99%

One- and Two-Color Resonant Photoionization Spectroscopy of Chromium-Doped Helium Nanodroplets

et al. 2014

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We investigate the photoinduced relaxation dynamics of Cr atoms embedded into superfluid helium nanodroplets. One- and two-color resonant two-photon ionization (1CR2PI and 2CR2PI, respectively) are applied to study the two strong ground state transitions z7P2,3,4° ← a7S3 and y7P2,3,4° ← a7S3. Upon photoexcitation, Cr* atoms are ejected from the droplet in various excited states, as well as paired with helium atoms as Cr*–Hen exciplexes. For the y7P2,3,4° intermediate state, comparison of the two methods reveals that energetically lower states than previously identified are also populated. With 1CR2PI we find that the population of ejected z5P3° states is reduced for increasing droplet size, indicating that population is transferred preferentially to lower states during longer interaction with the droplet. In the 2CR2PI spectra we find evidence for generation of bare Cr atoms in their septet ground state (a7S3) and metastable quintet state (a5S2), which we attribute to a photoinduced fast excitation–relaxation cycle mediated by the droplet. A fraction of Cr atoms in these ground and metastable states is attached to helium atoms, as indicated by blue wings next to bare atom spectral lines. These relaxation channels provide new insight into the interaction of excited transition metal atoms with helium nanodroplets.

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“…In this context, chromium (Cr) and copper (Cu) atoms embedded in He droplets were studied by means of REMPI spectroscopy [96][97][98]. The main outcome of that work has been that absorption lines are broadened and shifted by hundreds of cm −1 indicating that the dopants are located inside the droplets.…”

Section: Rempi Spectroscopymentioning

confidence: 99%

“…Even the transition metal atoms Ag [118,128], Cr and Cu [96][97][98], which are initially submerged in the He droplet interior, are found to partly desolvate upon excitation and to leave the droplets as free atoms (see section III).…”

Section: Ion Imagingmentioning

confidence: 99%

Photoionisaton of pure and doped helium nanodroplets

Mudrich

Stienkemeier

2014

International Reviews in Physical Chemistry

118

114

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Helium nanodroplets, commonly regarded as the "nearly ideal spectroscopic matrix", are being actively studied for more than two decades now. While they mostly serve as cold, weakly perturbing and transparent medium for high-resolution spectroscopy of embedded molecules, their intrinsic quantum properties such as microscopic superfluidity still are subject-matter of current research. This article reviews recent work on pure and doped He nanodroplets using PI spectroscopy, an approach which has greatly advanced in the past years. While the notion of the ideal spectroscopic matrix mostly no longer holds in this context, photoionization techniques provide detailed insights into the photo-physical properties of pure and doped He nanodroplets and their relaxation dynamics following electronic excitation. Exploiting nowadays available high laser fields, even highly ionized states of matter on the nanoscale can be formed. Our particular focus lies on recent experimental progress including fs time-resolved spectroscopy, photoion and electron imaging, and novel sources of highly energetic radiation.

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Fano resonances in chromium photoionization spectra after photoinduced ejection from a superfluid helium nanodroplet

Cited by 13 publications

References 22 publications

Electronic Relaxation after Resonant Laser Excitation of Cr in Superfluid Helium Nanodroplets

Electronic Relaxation after Resonant Laser Excitation of Cr in Superfluid Helium Nanodroplets

One- and Two-Color Resonant Photoionization Spectroscopy of Chromium-Doped Helium Nanodroplets

Photoionisaton of pure and doped helium nanodroplets

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