H. Figger

Laser Physics at the Limits

Application of Atomic Clocks.- Achievements in Optical Frequency Metrology.- Towards an Optical Hydrogen Clock.- Methane Frequency Standard for Precision Measurements.- The Parametric Frequency-Interval Divider.- External Laser Stabilization.- Miniaturized Laser Magnetometers and Clocks.- High-Noise, Low-Resolution Spectroscopy.- Two-Photon Spectroscopy of Hydrogen.- Precision Spectroscopy on the Lyman-? Transitions of H and He.- Towards Laser Spectroscopy of Antihydrogen.- Ramseyfication of the Resonant Nonlinear Faraday Effect.- Sensitive Detection Techniques of Laser Overtone Spectroscopy.- Multiple-Beam Atom Interferometry: An Overview.- Pursuing Fundamental Physics with Novel Laser Technology.- Precision Optical Measurements and Fundamental Constants.- Quantum Electrodynamics and All That.- Lasers to Test Fundamental Physics in Space.- Measuring the Birefringence of the QED Vacuum.- Observing Mechanical Dissipation in Quantum Vacuum: An Experimental Challenge.- Precision in Length.- Probing an Optical Field with Atomic Resolution.- From Spectral Relaxation to Quantified Decoherence.- Laser Cooling of Trapped Ions.- Conditional Spin Resonance with Trapped Ions.- From Diode Laser to Atom Laser.- Optical Components for a Robust Bose-Einstein Condensation Experiment.- From Atoms to Single Biomolecules Through Bose-Einstein Condensates: Un Saluto da Firenze per Theodor.- Cavity Cooling with a Hot Cavity.- Zeeman-Tuned Slowing: Surfing the Resonance Wave.- A New Approach for Laser Cooling of Calcium.- The Design of Enhancement Cavities for Second Harmonic Generation.- Raman Technique for Femtosecond Pulse Generation.- High-Order Harmonics and White Light: Looking for Fringes and Finding Much More.- MeV Electrons and Positrons from a Femtosecond Table-Top Laser System.- Small Molecules in Intense Laser Fields - Dissociation and Stabilization.- Linear and Nonlinear Raman Spectroscopy of Gases.- Nonlinear Properties of Laser-Generated Giant Surface Acoustic Wave Pulses in Solid Materials.- Radiative Control and Quantum Engineering: Single Atom Wants to Meet Single Photon.- Optical Lattices as a Playground for Studying Multiparticle Entanglement.- Efficient Generation of Polarization-Entangled Photon Pairs with a Laser Diode Source.- Small is Beautiful.- Atomic Looping.- A Toroidal Magnetic Guide for Neutral Atoms.- Si29 Nanoparticles: A New Form of Silicon.- Molecular Self-Assembly.

Coherent control at its most fundamental: carrier-envelope-phase-dependent electron localization in photodissociation of a H2(+) molecular ion beam target.

Measurements and calculations of the absolute carrier-envelope-phase (CEP) effects in the photodissociation of the simplest molecule, H2(+), with a 4.5-fs Ti:sapphire laser pulse at intensities up to (4±2)×10(14)  W/cm2 are presented. Localization of the electron with respect to the two nuclei (during the dissociation process) is controlled via the CEP of the ultrashort laser pulses. In contrast to previous CEP-dependent experiments with neutral molecules, the dissociation of the molecular ions is not preceded by a photoionization process, which strongly influences the CEP dependence. Kinematically complete data are obtained by time- and position-resolved coincidence detection. The phase dependence is determined by a single-shot phase measurement correlated to the detection of the dissociation fragments. The experimental results show quantitative agreement with ab initio 3D time-dependent Schrödinger equation calculations that include nuclear vibration and rotation.

Chemiluminescent reaction between alkali dimers and oxygen molecules

The reaction of alkali dimers with oxygen molecules was studied in a crossed‐beam experiment. Weak luminescence from the crossing zone was observed. It was found that it was predominantly emitted by the electronically excited products of the reactions M2+O2→MO2+M* and M2+O2→MO*2+M (*=electronic excitation). Lower limits for the dissociation energies between M and O2 in the product molecules were derived from the cut‐off wavelengths of the continuous chemiluminescence spectra observed. They are found to be consistent with the values calculated using an ionic model for the product molecule MO2.

Spectroscopy of triatomic hydrogen

The visible emission spectra of H3, D2H, H2D and D3 were studied. Triatomic hydrogen molecules were produced by neutralization of fast ion beams in alkali vapors. In addition to the well-known 0-0 bands, weak vibrational bands of the electronic 3p2A″2 → 2s2A′1 transition of D3 and D2H were observed and analyzed. From the decay of the emission along the molecular beam lifetimes of excited states were obtained. For all observed states, 3p2A″2, 3s2A′1 and 3d, lifetimes strongly depend on the isotopic mixture. Many lifetimes measured were considerably shorter than ab initio predictions of the radiative lifetimes. Thus radiationless decay is important for all these excited states. Predissociation of the 3p2A″2 state increases with the rotational quantum number. Possible decay channels are discussed.

Spectroscopy of triatomic hydrogen. II: Bands near 4500 and 7100 Å

The strongest emission band of triatomic hydrogen near 7100 Å was observed after neutralization of mass-selected ion beams of H3+, H2D+, D2H+ and D3+. For D3 improved molecular constants were determined by inclusion of higher rotational lines. Lifetimes of the upper states of the 7100 Å band were measured. They strongly decrease for the lighter isotopomers because of predissociation. New emission bands of D3 observed between 4200 Å and 4600 Å are assigned to transitions betweenn=4 andn=2 states.

Laser spectroscopy ofD3

Abstract The D 3 was formed in a hollow cathode discharge in D 2 . Transitions between the states 3p 2 E′, 3p 2 A″ 2 and 2S 2 A′ 1 were stimulated by dye-laser radiation. The resonances were monitored by observng the laser-induced change of the emission from selected levels of D 3 . Many new lines were observed and assigned.

Ar+2 molecules in intense laser fields

Abstract We have studied the interaction between intense laser fields (⩽ 7 × 10 12 W/cm 2 ) and molecules. For the diatomic molecular ion Ar + 2 the number of photofragments as a function of laser intensity can be quantitatively explained in terms of light-induced adiabatic molecular potentials. The effects predicted by this model tend to cancel under realistic experimental conditions with a thermal distribution of the rovibrational populations. This molecular beam experiment allows for a fully quantitative comparison with theory, since only one dissociation channel is operative and all parameters relevant for a computational simulation have been determined.

Lifetime measurements on ArH and ArD

We present results of lifetime measurements of rotational substates of the E  2Π state in the Rydberg molecules 40ArH and 40ArD. We find reasonable agreement between our result and theoretical predictions in the case of ArH. However, for ArD we obtain a distinctively longer lifetime than for the lighter isotopic molecule, ArH, which is not unusual for hydrides but is not accounted for by theory. In addition, different lifetimes measured for the Q and R,P‐branch, respectively, emitting levels of the E  2Π state in ArD, give interesting insight into the interaction between excited Rydberg states of this molecule. The dependence of the lifetime of levels emitting the Q‐branch on the rotational quantum number N for N≳19 is also investigated. Furthermore, the lifetime of the state(s) responsible for the continuous emission in the ultraviolet (UV) region was measured at discrete wavelengths for each of the molecules 40ArH and 40ArD. Our results, together with theoretical predictions, clearly favor the assignment of the UV continuum to two electronic states, namely B  2Π and E  2Π.

Observation of the ND4 Schüler band in a neutralized ion beam experiment

The emission of the ND4 Schüler band was observed after neutralization of a mass-selected ND4+ ion beam. Thus the assignment of this band to the ammonium radical was confirmed. The lifetime of the upper state (3p2F2) was determined to be 4.2 ns, which is much shorter than ab initio values of the radiative lifetime, showing that this state decays predominantly by predissociation. The Schuster band was not observed, neither after neutralization of ND4+, nor of ND3+.

Labelling spectroscopy on argonhydride and argondeuteride in a plasma beam penning tube

Rare gas hydride molecules and triatomic hydrogen molecules were produced in a Cossart-type plasma beam Penning tube specially designed for laser spectroscopic work. A cw dye laser was used to stimulate transitions from theB2Π rovibrational levels to theA2Σ+ levels of argonhydride (40ArH) and argondeuteride (40ArD). The transitions were detected by measuring the decrease of the spontaneous emission from the upper levels, which clearly shows the expected population inversion between the two participating electronic states. With this first laserspectroscopic work on argonhydride and argon deuteride, the classification of the lines of theB2Π→A2Σ+ band as given by Johns 1970 could be checked and was found to be consistent*. Furthermore theQ branches of these bands for ArH and ArD could be completely resolved into their single lines and their wavelengths were measured. The latter allowed the difference between the rotational constants of theA andB electronic states to be directly determined. The method was also applied to triatomic hydrogen. D3. It should be useful for classifying more complicated bands of ArH and of KrH and XeH, which can also be produced in this tube.