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28 December 2006
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Headline news:
In a collaboration of the Vauthey (Université de
Génève, Switzerland) and Nibbering (MBI) groups
strongly and weakly coupled ion pairs have been observed in
photoinduced bimolecular electron transfer reactions in solution.
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Link to original paper |
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One sentence summary:
The asymmetric CN-stretching mode of 1,4-dicyanobenzene radical
anion provides insight into the ultrafast formation and decay
times of strongly and weakly coupled ion pairs as well as the
dissociation of geminate ion pairs on picosecond time scales. |
More details
on page of subproject 2 |
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The broader peak at early pulse delays is attributed to
the radical anion CN-stretching vibration within a strongly
coupled ion pair, formed by ultrafast "static" quenching
of the photoexcited perylene chromophore. A band narrowing
on a time scale of a few tens of picoseconds observed on the
antisymmetric CN stretching vibration of the dicyanobenzene
radical anion indicates that a substantial part of the excess
energy is channeled into vibrational modes of the product,
despite the fact that the reaction is weakly exergonic. An
additional narrowing of the same band on a time scale of several
hundreds of picoseconds observed in acetonitrile only is interpreted
as a signature of the dissociation of the geminate ion pairs
into free ions.
 
The research team at the MBI in summer 2005 during the first
measurment period: Dr. Bernhard Lang, Omar F. Mohammed, Nathalie
Banerji and Dr. Erik T. J. Nibbering.
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External funding by:
Fonds National Suisse: Project 200020-107466.
LIMANS Cluster of Large Scale Facilities: MBI001176.
Cultural department and study mission (Kulturabteilung und
Studienmission) of the Embassy of the Arabic Republic Egypt
(Omar F. Mohammed).
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Contact: Erik T. J.
Nibbering
Contact: Eric
Vauthey |
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4 December 2006
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Headline
news:
Observation of coherent wavepacket modulations of the
amino hydrogen bond of the 7-azaindole dimer. |
Link to original paper |
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One sentence
summary:
Femtosecond N–H stretching excitation induces coherent underdamped
motions of the 7-azaindole dimer, dominated by the anharmonically
coupled 110 cm-1 stretching mode of the hydrogen bonds. |
More details
on page of subproject 1 |
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The low-frequency dimer stretching mode of 7-azaindole dimer
anharmonically coupled to the N-H stretching mode.
Dr. Jason R. Dwyer prepares for the two colour pump-probe
experiments.
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External funding by:
German Science Foundation: SFB450-B2 (Sonderforschungsbereich
450 "Analyse und Steuerung ultraschneller photoinduzierter
Reaktionen").
Natural Sciences and Engineering Research Council of Canada
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Contact: Erik T. J.
Nibbering
Contact: Thomas Elsaesser
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12 October 2006
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Headline
news:
Klaus Tschira Preis für verständliche Wissenschaft 2006
für Dr. Nils Huse. |
Pressemitteilung |
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One sentence
summary:
Physiker des Max Born Instituts erhält den Klaus
Tschira Preis für verständliche Wissenschaft 2006 für
seine klare Darstellung von Forschungsergebnissen: Das
kurze Gedächtnis des Wassers, wo er schildert, wie die moderne
Experimentalphysik die Anomalien von Wasser erforscht. |
Klaus Tschira
Stiftung
Studienstiftung des deutschen Volkes
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Die Preisverleihung
fand am 12. Oktober 2006 in der Alten Aula der Universität
Heidelberg statt.
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Bild
der Wissenschaft Plus: Sonderveröffentlichung enthält
die Originalbeiträge der Preisträger, sowie Informationen
über die Studienstiftung des deutschen Volkes und die Klaus
Tschira Stiftung
Preisträger:
Informationen über den beruflichen Werdegang der Preisträger
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21 August 2006
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Headline news:
Mode-selective O–H stretching relaxation in a hydrogen
bond observed to occur via overtone and combination bands
in which the O-H bending mode plays a dominant role. |
Link to original paper |
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One sentence summary:
Transient IR-pump/IR-probe and IR-pump/resonance Raman probe
measurements grasp the vibrational energy flow pathway in TINUVIN. |
More details
on page of subproject 3 |
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Energy level scheme (harmonic scaling) for selective relaxation
of the O-H stretching band excitation into fingerprint mode
over- and combination tones.
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External funding by:
German Science Foundation: DFG-WE 1489/6 .
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Contact: Wolfgang Werncke
Contact: Thomas Elsaesser
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20 July 2006
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Headline
news:
Lise-Meitner Preis für Dr. Nils Huse. |
Pressemitteilung |
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One sentence
summary:
Physiker des Max Born Instituts erhält Preis für seine
herrausragende Doktorarbeit auf der Festveranstaltung des Instituts
für Physik und der Vereinigung der Freunde und Förderer
des Instituts für Physik e.V. der Humboldt Universität
zu Berlin. |
Freunde und Förderer
der Physik der HU Berlin
Institut für
Physik
Humboldt-Universität zu Berlin
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Übergabe des Lise-Meitner-Preises durch den Vorsitzenden
des Vorstandes der Freunde der Physik, Prof. M. Müller-Preußker
an Dr. Nils Huse (MBI) für seine herausragende Dissertation
(Fotogalerie)
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Scienzz
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12 June 2006
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Headline
news:
The Elsaesser/Nibbering team report on the femtosecond
dynamics of coupled O H stretching and bending excitations
in neat water (H2O), revealing a Fermi resonance
between the O H stretching and bending vibrations. |
Link to original paper |
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One sentence
summary:
Transient vibrational spectra and their kinetics reveal a Fermi
resonance between the O H stretching and bending vibrations
and femtosecond lifetimes of the intramolecular vibrational
excitations of liquid water. |
More details on page of subproject
1 |
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The Berlin team members Satoshi Ashihara (guest scientist
from the Institute of Industrial Science, University of Tokyo,
Tokyo, Japan) and Nils Huse discussing vibrations in water..
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What are
O-H stretching and bending modes?
Examples given here. (click on images for animated gif-files
6 MB)
 
Stretching vibration of the water molecule. An ultrashort
infrared pulse excites the asymmetric stretching vibration
of the angled water molecule (red: oxygen atom, gray: hydrogen
atom). The water molecule is part of a network of hydrogen
bonds between the hydrogen and oxygen atoms on neighboring
molecules (small gray symbols). Shown are the elongations
of the atoms during the stretching vibration with a vibrational
period of 10 fs. (Animation by Jens Dreyer, MBI)
 
Bending motion of water. A period of the bending mode shown
lasts approximately twice as much as that of the O-H stretching
mode, i.e. 20 fs. The first overtone (v=2) level can thus
be found at a frequency close to that of the fundamental of
the O-H stretching vibration, facilitating an efficient Fermi
resonance coupling mechanism. (Animation by Jens Dreyer, MBI)
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External funding by:
German Science Foundation: SFB450-B2 (Sonderforschungsbereich
450 "Analyse und Steuerung ultraschneller photoinduzierter
Reaktionen").
 Mizuho
Foundation for the Promotion of Sciences (S. Ashihara)
Alexander von Humboldt Foundation (A. Espagne).
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Contact: Erik T. J.
Nibbering
Contact: Thomas Elsaesser
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