arXiv subjects

J. Peter Toennies

Publications and source records attributed to J. Peter Toennies.

4 recordsLinked to original sources

arXiv2011

Otto Stern (1888-1969): The founding father of experimental atomic physics

We review the work and life of Otto Stern who developed the molecular beam technique and with its aid laid the foundations of experimental atomic physics. Among the key results of his research are: the experimental determination of the Maxwell-Boltzmann distribution of molecular velocities (1920), experimental demonstration of space quantization of angular momentum (1922), diffraction of matter waves comprised of atoms and molecules by crystals (1931) and the determination of the magnetic dipole moments of the proton and deuteron (1933).

physics.hist-ph↗

arXiv2010

The HF(v'=3) forward scattering peak of the F + H2 reaction revisited

A quantum mechanical coupled-channel scattering calculation on the Stark-Werner potential energy surface is used to study the F + H2(v=0; j=0,1,2) ---> H + HF(v', j') reaction at collision energies of 1.84, 2.74, and 3.42 kcal/mol. The dependence of the vibrationally and rotationally resolved differential cross sections on the product vibrational levels v'=0, 1, 2, and 3 as well as on the reactant and product rotational levels is analyzed. The HF(v'=3) center-of-mass forward scattering peak is shown to be caused by the superposition of two effects, namely, the absence of the HF(v'=3; j') products with large j' values due to energy constraints and the growth of the rotationally resolved HF(v', j') forward scattering peak with small j' values as v' increases.

physics.chem-ph↗

arXiv2002

The van der Waals Potential between Metastable Atoms and Solid Surfaces: Novel Diffraction Experiments versus Theory

Highly polarizable metastable He* ($\mathrm{2^3S}$) and Ne* ($\mathrm{2^3P}$) atoms have been diffracted from a 100 nm period silicon nitride transmission grating and the van der Waals coefficients $C_3$ for the interaction of the excited atoms with the silicon nitride surface have been determined from the diffraction intensities out to the 10th order. The results agree with calculations based on the non-retarded Lifshitz formula.

quant-ph↗

arXiv1997

Density of Superfluid Helium Droplets

The classical integral cross sections of large superfluid 4He_N droplets and the number of atoms in the droplets (N=10^3-10^4) have been measured in molecular beam scattering experiments. These measurements are found to be in good agreement with the cross sections predicted from density functional calculations of the radial density distributions with a 10-90 % surface thickness of 5.7Å. By using a simple model for the density profile of the droplets a thickness of about 6-8Åis extracted directly from the data.

cond-mat↗