Ultrafast probing of ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets

Journal Article · Fri Dec 07 04:00:00 EST 2012 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4768422· OSTI ID:22099121

Buenermann, Oliver; Kornilov, Oleg; Neumark, Daniel M. ^[1]; Haxton, Daniel J.; Gessner, Oliver ^[1]; Leone, Stephen R. ^[1]

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1. Ultrafast X-ray Science Laboratory, Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

The ejection dynamics of Rydberg atoms and molecular fragments from electronically excited helium nanodroplets are studied with time-resolved extreme ultraviolet ion imaging spectroscopy. At excitation energies of 23.6 {+-} 0.2 eV, Rydberg atoms in n= 3 and n= 4 states are ejected on different time scales and with significantly different kinetic energy distributions. Specifically, n= 3 Rydberg atoms are ejected with kinetic energies as high as 0.85 eV, but their appearance is delayed by approximately 200 fs. In contrast, n= 4 Rydberg atoms appear within the time resolution of the experiment with considerably lower kinetic energies. Major features in the Rydberg atom kinetic energy distributions for both principal quantum numbers can be described within a simple elastic scattering model of localized perturbed atomic Rydberg atoms that are expelled from the droplet due to their repulsive interaction with the surrounding helium bath. Time-dependent kinetic energy distributions of He{sub 2}{sup +} and He{sub 3}{sup +} ions are presented that support the formation of molecular ions in an indirect droplet ionization process and the ejection of neutral Rydberg dimers on a similar time scale as the n= 3 Rydberg atoms.

• OSTI ID: 22099121
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 21 Vol. 137; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
CATIONS
DIMERS
ELASTIC SCATTERING
EV RANGE 10-100
EXTREME ULTRAVIOLET RADIATION
HELIUM
HELIUM IONS
KINETIC ENERGY
MOLECULAR IONS
PHOTOIONIZATION
PHOTON-MOLECULE COLLISIONS
QUANTUM NUMBERS
RYDBERG STATES
SPECTROSCOPY
TIME RESOLUTION
ULTRAVIOLET SPECTRA