Observation of an amplitude collapse and revival of chirped coherent phonons in bismuth

We have studied the A(1g) coherent phonons in bismuth generated by high fluence ultrashort laser pulses. We observed that the nonlinear regime, where the phonons' oscillation parameters depend on fluence, consists of subregimes with distinct dynamics. Just after entering the nonlinear regime, the phonons become chirped. Increasing the fluence further leads to the emergence of a collapse and revival, which next turns into multiple collapses and revivals. This is explained by the dynamics of a wave packet in an anharmonic potential, where the packet periodically breaks up and reconstitutes in its original form, giving convincing evidence that the phonons are in a quantum state, with no classical analog.     

Spontaneous transfer of phospholipid-coated oil-in-oil and water-in-oil micro-droplets through an oil/water interface

We studied the evolution of oil-in-oil (O/O) and water-in-oil (W/O) phospholipid-coated micro-droplets at an oil/water interface. We found that, in both cases, micro-droplets spontaneously transferred from the oil phase to the water phase. O/O micro-droplets transformed into oil-in-water micro-droplets, while W/O micro-droplets led to the formation of liposomes.     

Die elektronenstruktur des arsenins (arsabenzols)

The electronic structure of arsenin has been investigated using an extended CNDO/2 approach. Orbital energies, ionization potentials, orbital and total electron density contour maps are given and compared with those of phosphorin and pyridine.     

Decomposition of chemically activated ethyltrimethylgermane the arrhenius A-factors for rupture of group IVA—methyl bonds

The decomposition rate of chemically activated ethyltrimethylgermane from the reaction ¹CH₂ + (CH₃)₄Ge, where ¹CH₂ was produced from diazomethane photolysis at 3660 Å, is 8.6 × 10⁵ sec^?1. This result combined with RRKM theory and critical energy estimates yields an Arrhenius A factor of log[A (sec^?1)/methyl] = 14.7 ± 0.8 for methyl rupture from germanium. Log A values for methyl rupture from carbon, silicon, and germanium linearly correlate with the vibrational-rotational entropies of the corresponding tetramethyls. Extrapolation predicts log[A (sec^?1)/methyl] = 14.4 and 14.3 for methyl rupture from tin and lead, respectively.     

On the applicability of slow passage EPR relaxation theories to saturation curves for trapped electrons in organic glasses

It is shown that the experimental microwave power saturation curves for trapped electrons in organic glasses do not fit the simple paramagnetic relaxation theories developed for inhomogeneous lines in the absence of magnetic field modulation. To understand experimental saturation data obtained in the presence of modulation, it is suggested that theoretical treatments must include magnetic field modulation effects.     

Phonon autoecho in bismuth and antimony single crystals

Phonon autoecho is observed upon pumping Bi and Sb semimetals with ultrashort high-energy laser pulses. The autoecho is manifested as a revival of reflection oscillations generated by an A_1g coherent phonon after their complete disappearance. The phenomenon of phonon autoecho offers decisive evidence of the nonclassical character of the state of the crystal lattice that is accomplished in pumping-probing experiments by femtosecond laser pulses.