Fragmentation in Intense Time-Dependent Fields

 The mechanism of enhanced ionization or charge-assisted tunneling, first discovered for small linear molecules under an intense laser pulse, is briefly reviewed. Then it is shown that this mechanism also applies to rare gas clusters in strong laser fields. A suitable observable which can be accessed experimentally, is the degree of ionization of the cluster as a function of the laser pulse length. Examples are given for Ne₁₆ and Ar₁₆. Received September 12, 2001; accepted for publication September 16, 2001     

Rescattering for extended atomic systems

Laser-driven rescattering of electrons is the basis of many strong-field phenomena in atoms and molecules. Here, we will show how this mechanism operates in extended atomic systems, giving rise to effective energy absorption. Rescattering from extended systems can also lead to energy loss, which in its extreme form results in nonlinear light-induced trapping. Intense-laser interaction with atomic clusters is discussed as an example. We explain fast electron emission, seen in experimental and numerically obtained spectra, by rescattering of electrons at the highly charged cluster.     

Generation of etch pits on sectional planes of unidirectionally solidified cd-zn eutectic samples

A series of experiments were carried out for generating defined etch pits on various sectional planes of unidirectionally solidified Cd-Zn eutectic samples. This was done as preliminaries of real structure investigations. For that purpose chemical, electrolytic, and ion beam procedures were tested.     

Fast Algorithms for Centro-Symmetric and Centro-Skewsymmetric Toeplitz-Plus-Hankel Matrices

Subject of the paper are centro-symmetric and centro-skewsymmetric Toeplitz-plus-Hankel matrices with the property that all central submatrices are nonsingular. Fast algorithms are presented that solve an n×n system of equations with O(n ²) operations in sequential and O(n) operations in parallel processing and compute the ZW-factorization with the same computational complexity. These algorithms are more efficient than existing algorithms because they fully exploit the symmetry properties of the matrices.     

Fast inversion algorithms of Toeplitz-plus-Hankel matrices

Summary The paper deals with the problems of fast inversion of matricesA=T+H, whereT is Toeplitz andH is Hankel. Several algorithms are presented and compared, among them algorithms working for arbitrary strongly nonsingular matricesA=T+H.     

Baryon resonance components in the deuteron

A non-relativistic coupled channel calculation of the structure of the deuteron is presented with NN¹ configurations in addition to the usual (NN) S- and D-state components. The additional baryon resonance degrees of freedom are included by means of a one-pion exchange potential model; the nucleon-nucleon interactions are treated with conventional phenomenological potentials which contain a hard core. This core obviates the necessity for additional cutoff parameters for the singular NN¹ potentials. All possible NN¹ states of the ten currently “well-established” N¹ resonances have been calculated using a renormalized Reid hard core potential and several NN¹ amplitudes are found in the 0.1–0.3% range. Some of these components are rather large at high momenta and thus may be observable in high momentum transfer processes.