Ultrafast relaxation of photoexcited superfluid He nanodroplets.
Nat Commun
; 11(1): 112, 2020 Jan 08.
Article
en En
| MEDLINE
| ID: mdl-31913265
ABSTRACT
The relaxation of photoexcited nanosystems is a fundamental process of light-matter interaction. Depending on the couplings of the internal degrees of freedom, relaxation can be ultrafast, converting electronic energy in a few fs, or slow, if the energy is trapped in a metastable state that decouples from its environment. Here, we study helium nanodroplets excited resonantly by femtosecond extreme-ultraviolet (XUV) pulses from a seeded free-electron laser. Despite their superfluid nature, we find that helium nanodroplets in the lowest electronically excited states undergo ultrafast relaxation. By comparing experimental photoelectron spectra with time-dependent density functional theory simulations, we unravel the full relaxation pathway Following an ultrafast interband transition, a void nanometer-sized bubble forms around the localized excitation (He[Formula see text]) within 1 ps. Subsequently, the bubble collapses and releases metastable He[Formula see text] at the droplet surface. This study highlights the high level of detail achievable in probing the photodynamics of nanosystems using tunable XUV pulses.
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Banco de datos:
MEDLINE
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En
Revista:
Nat Commun
Asunto de la revista:
BIOLOGIA
/
CIENCIA
Año:
2020
Tipo del documento:
Article
País de afiliación:
Dinamarca