Ultrafast photoinduced dynamics of single atoms solvated inside helium nanodroplets.
J Chem Phys
; 152(1): 014307, 2020 Jan 07.
Article
em En
| MEDLINE
| ID: mdl-31914752
ABSTRACT
Helium nanodroplets can serve as reaction containers for photoinduced time-resolved studies of cold, isolated molecular systems that are otherwise inaccessible. Recently, three different dynamical processes, triggered by photoexcitation of a single atom inside a droplet, were observed in their natural time scale Expansion of the He solvation shell (He bubble) within 600 fs initiates a collective bubble oscillation with a â¼30 ps oscillation period, followed by dopant ejection after â¼60 ps. Here, we present a systematic investigation of these processes by combining time-resolved photoelectron and photoion spectroscopy with time-dependent He density functional theory simulations. By variation of the photoexcitation energy, we find that the full excess excitation energy, represented by the blue-shifted in-droplet excitation band, is completely transferred to the He environment during the bubble expansion. Surprisingly, we find that variation of the droplet size has only a minor influence on the ejection time, providing insight into the spatial distribution of the ground-state atoms before photoexcitation. Simulated particle trajectories after photoexcitation are in agreement with experimental observations and suggest that the majority of ground-state atoms are located at around 16 Å below the droplet surface. Bubble expansion and oscillation are purely local effects, depending only on the ultimate dopant environment. These solvation-induced dynamics will be superimposed on intramolecular dynamics of molecular systems, and a mechanistic description is fundamental for the interpretation of future experiments.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Chem Phys
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Áustria