aktualisiertes pdf - DPG-Tagungen

Fachsitzungen
– Fach-, Kurzvorträge und Posterbeiträge –
MO 1 Experimentelle Techniken
Zeit: Montag 11:00–11:30 Raum: HS 332
Fachvortrag MO 1.1 Mo 11:00 HS 332
Autler-Townes effect as a probe of properties of excited
molecular states. — •R. Garcia Fernandez 1 , A. Ekers 1 , J.
Klavins 2 , L.P. Yatsenko 3 , N.N. Bezuglov 4 , O. Kaufmann 1 ,
B.W. Shore 1 , and K. Bergmann 1 — 1 FB Physik, TU Kaiserslautern.
— 2 Dept. of Physics, University of Latvia, Riga. — 3 Inst. of Physics of
the Academy of Sciences, Kiev, Ukraine. — 4 V.A. Fock Inst. of Physics,
Univ. St.Petersburg, Russia
A novel method for the characterization of highly excited molecular
states utilizing the Autler-Townes splitting is demonstrated for Na2
molecule. The experiment employs a supersonic beam and a cascade
scheme X1Σ + g → A1Σ + u → 51Σ + g (or 61Σ + g ), with a cw probe laser in
the first step and a cw dressing laser in the second step. The variation of
the fluorescence intensities from the intermediate and upper levels with
the frequency of the pump and probe lasers contains information about
the lifetime and branching ratio of the upper state. These quantities can
be easily accessed by a proper choice of the detuning of pump laser from
the resonance and the intensity of the probe laser. The lifetime of the
51Σ + g state is measured to be about the same as that of the intermediate
A 1 Σ + u state, while for 61 Σ + g it is twice as large. The 51 Σ + g
state decays
almost exclusively to the A 1 Σ + u state, but decay of the 6 1 Σ + u occurs predominantly
through other channels.
MO 2 Experimentelle Techniken, Kalte Moleküle
Zeit: Montag 11:30–12:45 Raum: HS 332
MO 2.1 Mo 11:30 HS 332
Laser Spectroscopy of Ultracold Molecular Hydrogen Ions
in a Linear RF-Trap — •Ulf Fröhlich 1 , Bernhard Roth 1 ,
Thomas Fritsch 1 , Claus Lämmerzahl 2 , and Stephan Schiller 1
— 1 Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf —
2 Universität Bremen, D-28359 Bremen
We present an experiment aimed at high-resolution spectroscopy of the
ro-vibrational level structure of HD + . As one of the simplest molecules,
HD + is particularly suitable to test theories of molecular structure.
The HD + molecular ions will be confined in a linear rf-trap and cooled
via Coulomb interaction by laser cooled Be + atomic ions confined in the
same trap (sympathetic cooling). At sufficient high cooling rates, the
laser cooled Be + ions undergo a phase transition to an ordered structure
(Coulomb crystal). Numerical simulations show, that one can expect the
HD + ions to be embedded in such a Be + ionic crystal. In this way, an
ultra-cold ensemble of HD + molecular ions can be prepared for highresolution
laser spectroscopy.
So far, we have prepared and characterized Be + ionic crystals of different
size and shape suitable for embedding HD + ions. Currently we are
trying to optimize the process of loading HD + and Be + ions into the
trap. Furthermore, we are now building up a stabilized laser system for
high-resolution spectroscopy of the (ν = 0, N = 4) - (ν = 4, N = 4)
transition of HD + at 1.4µm.
MO 2.2 Mo 11:45 HS 332
COOL MOLECULAR MICRO-BEAMS, FRIGID CLUSTERS,
AND GELID MOLECULAR DIFFRACTION IMAGES —
•Bretislav Friedrich — Fritz-Haber-Institut der MPG, Faradayweg
4-6, D-14195 Berlin
I will describe a versatile molecular beam source, employing supersonic
flow, pulsing, and ablation in a way that minimizes size and pumping requirements.
The performance of the source is exemplified by producing a
cool pulsed supersonic molecular beam of CaF radicals, essentially without
recourse to pumping. About 10 12 CaF molecules cooled to a terminal
temperature of about 140 K are obtained per ablation pulse.
We have developed a general technique for orienting molecules,
amenable to a wide variety of species and applications. The key aspect
is to endow a polar molecule with a pseudo-first-order Stark effect. I will
describe how this effect comes about and discuss its use in the detection
of gas-phase HXeI clusters, generated by the photolysis of HI embedded
in the outer shells of large Xen clusters.
I will also describe a versatile imaging detector for neutral atoms and
molecules based on reactions with a vacuum-deposited silver surface. The
detector is endowed with the Fellgett advantage, has a demonstrated
sensitivity of several monolayers of molecules, and a dynamic range of
at least 100:1. One of the immediate applications of the detector in our
47
cold-molecule effort will be to determining the velocity distributions of
slow/cold molecules. These are convoluted in a diffraction pattern and
can be extracted with a high accuracy from an observed diffraction image.
MO 2.3 Mo 12:00 HS 332
Anwendung kalter, langsamer Moleküle zur hochauflösenden
Spektroskopie: Die Hyperfeinstruktur von 15 ND3. — Jacqueline
van Veldhoven 1 , •Jochen Küpper 2 , Boris Sartakov 3 , Hendrick
L. Bethlem 1 und Gerard Meijer 2 — 1 FOM Instituut voor Plasmafysica
“Rijnhuizen”, Nieuwegein, Die Niederlande — 2 Fritz-Haber-Institut
der MPG, Abt. Molekülphysik, Berlin — 3 Russian Academy of Science,
Inst. Gen. Phys., Moskau 119991, Rußland
Ultimativ ist die Auflösung jedes spektroskopischen Experiments durch
die Interaktionszeit zwischen untersuchtem Objekt und Messgerät limitiert.
In den letzten Jahren sind verschiedene Methoden zur Erzeugung
kalter, langsamer Moleküle entwickelt worden. In unserer Gruppe erzeugen
wir aus einem Überschallstrahl mit Hilfe geschalteter elektrischer
Felder Bündel langsamer und kalter Moleküle [1]. In dieser Arbeit haben
wir 15 ND3 im |11〉-Zustand auf 50 m/s abgebremst und an den langsamen
Molekülen Mikrowellen-UV Doppelresonanzspektroskopie durchgeführt.
Wir präsentieren Ergebnisse zum Inversionstunnelübergang von 15 ND3
bei 1, 59 GHz mit einer Linienbreite von etwa 1 kHz. Die gegenüber den
bisher höchstauflösenden Messungen [2] deutlich verringerte Linienbreite
ermöglicht es einzelne Hyperfeinübergänge aufzulösen und die Hyperfeinstruktur
von 15 ND3 präzise auszuwerten.
[1] H.L. Bethlem und G. Meijer, Int. Rev. Phys. Chem. 22, 73 (2003)
[2] J. van Veldhoven, R.T. Jongma, B. Sartakov, W.A. Bongers, und G.
Meijer, Phys. Rev. A 66, 032501 (2002).
MO 2.4 Mo 12:15 HS 332
Generation of cold atoms and molecules by a rotating nozzle:
recent progress — •D.H. Meyer, N.-N. Liu, and H.J. Loesch —
Fakultaet fuer Physik, Universitaet Bielefeld, Universitaetsstrasse 25, D-
33615 Bielefeld
The rotating nozzle is an universal mechanical device to create a (quasi)
continuous beam of cold atoms and molecules. To date we have achieved
a Xe-beam featuring a most probable velocity of 40 m/s at a parallel
translational temperature of T(par) =10.4 K and 20 at 20 m/s. Similar
results have been obtained also for Kr. Modifications of the apparatus
are being realized presently with the aim to lower the peak velocity further
and to exploit the cold atoms as carrier gases for polar molecules.
We will report on the results of these activities and on first experiments
about the manipulation of the cold molecules by inhomogeneous electric
fields. The applicability of the rotating nozzle for the continuous storage
of molecules in a ring trap will be discussed.