H. G. Weber

An optical pumping-experiment of ortho- and para-states of Na2-molecules

Abstract In an optical pumping experiment on Na it is shown that the polarization of the alkali atoms influences the Na2 density as well as the relative abundances of the ortho and para modifications of the Na2 dimers.

Optical pumping method for studying nuclear-spin polarization in alkali dimers

Magnetic resonance of133Cs nuclei was observed in free Cs2 dimers employing the method of optical pumping in combination with atom-molecule nuclear orientation transfer. This novel method allows measurements ofn m r spectra in free diamagnetic molecules, atom-dimer exchange cross sections, dissociative collision cross sections of dimers against buffer gases and intramolecular relaxation. The dimer-atom exchange cross section for Cs-Cs2 isσDE=(1.9±0.4)·10−14cm2, the dissociative dimer-buffergas collisions show the expected exponential behaviour in temperature.

NMR of Cs+ involving photoionization, optical pumping and charge exchange

Abstract NMR of free Cs+ ions yielded μ I ( 133 Cs + ) = 2.56317( 2) . A strong resonance frequency shift proportional to the amplitude of the rf field H1 times the static field H0 was observed.

Unexpected properties of a quantum mechanical system

Abstract The free NO 2 molecule is prepared into a well defined, isolated quantum state. We report however experimental results which contradict our knowledge on the properties and dynamical behaviour of a molecule in an isolated quantum state.

Magnetic shielding and spin-rotation interaction in ground state alkali molecules

Precision measurements of nuclear magnetic dipole moments in alkali molecules are performed using atom-molecule exchange optical pumping. A comparison with measurements on alkali atoms gives the magnetic shielding differences between atoms and molecules and an approximate value for the spin-rotation interaction constant of the alkali molecules. It is reported on experiments on39K2 and87Rb2.

Magnetic field decoupling experiments in NO2

Magnetic field decoupling experiments in the optically excited states of NO2 yield decoupling signals with a width of 10 to 40 mG. We attribute these signals to the non-rigidity of the excited molecule.

Frequency shifts in charge-exchange optical pumping experiments

Abstract A resonance frequency shift observed in an nmr experiment on free 133 Cs + ions can be explained by the resonant charge-exchange-process with Cs.

Preparation and decay of an excited molecular state studied by optical-rf double resonance

Abstract In an optical-radio-frequency double-resonance experiment on NO 2 a broad resonance structure appears superimposed on the normal magnetic resonance spectrum. We show here that the broad resonance structure is associated with the preparation of the free molecule into an initial state and the subsequent, fast (relative to photon emission) evolution into another (long-lived) state from which it decays radiatively. The results confront us with an interesting problem concerning the time evolution of a quantum mechanical system.

A new molecular fluorescence depolarization effect: The coherence decay time of NO2

Measurements of the coherence decay of NO2 by zero magnetic field level crossing (Hanle effect) reveal a novel depolarization effect of the fluorescence light not known from similar experiments on atoms and diatomic molecules.

Non-stationary states in molecular spectroscopy: The Hanle effect in NO2

The excited state NO2 molecule is described as a nonrigid molecule capable of changing between two asymmetric equilibrium configurations. The tunnelling motion introduces a narrow level splitting in this molecule and causes the optically prepared states to be non-stationary states. This explains the different lifetimes obtained from radiative decay measurements and from Hanle effect measurements on NO2.