21st Century Nanoscience – A Handbook

Abstract

Two emerging areas of research, attosecond and nanoscale physics, have recently started to merge. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto-and sub-femtosecond time scales, interact with atoms, molecules or solids. The laserinduced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond=1 as=10 −18 s), which is of the order of the optical field cycle. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is ∼ 152 as. On the other hand, the second topic involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the combination with intense laser physics is relatively recent. We present a comprehensive theoretical overview of the tools to tackle and understand the physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics. Consequently, this has important impact on pivotal processes such as above-threshold ionization and high-order harmonic generation. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nano physics has begun, but it is still in an incipient stage.

Analytical model of the network topology and rigidity of calcium aluminosilicate glasses

“…This agrees with the excellent glass-forming ability of SiO 2 . 19,30 It should be noted that SiO 2 exhibits a high glass-transition temperature, so that, unlike other silicate glasses, the topological origin of its glass-forming ability should indeed be assessed at high temperature (i.e., wherein the BB constraints of the BO atoms are thermally broken). The state of rigidity of the CAS ternary system at moderate temperature (Figure 7B,C) also exhibits some correlations with glass-forming ability.…”

“…22 Importantly, predictions from TCT critically rely on an accurate knowledge of the glass structure and connectivity, which is the key to enumerate the number of BS and BB constraints created by each type of atoms in the glass network. 30 This is a challenge as the local structure of glasses (and hence, the number of constraints) changes as a function of composition. For instance, CAS glasses exhibit several structural complexities, for example, overcoordinated Al atoms, 5,[31][32][33] tricluster oxygen units, 34 free oxygen (FO) species, 35,36 varying Ca environments, 37 etc.…”

“…All these features impact the constraints enumeration and, hence, should be accounted for in robust topological models. Although such information can be accessed by molecular dynamics (MD) simulations of one composition at a time, 30 it is not practical to systematically conduct MD simulations over large compositional domains considering their high computational cost. In addition, discrete models (e.g., relying on a finite, discrete number of MD simulations) are not differentiable, that is, they do not allow for the computation of the derivative of the n c with respect to composition.…”

“…57 Second, since BO and TO atoms are already fully charge-compensated by their Si or Al neighbors, we assume that Ca atoms only create strong BS constraints with their surrounding FO and NBO neighbors. Finally, each BO atom creates one BB constraint (e.g., to maintain Si/Al-O-Si/Al angles fixed around their average values), whereas each TO atom creates three BB constraints to define its trigonal environment 30. In contrast, FO and NBO atoms do not create any BB constraint due to the nondirectional nature of ionic Ca-O bonds.…”

Attoscience in Phase Space

“…This also implies that a densitymatrix formalism and effective Hamiltonians [149,155], which are more suitable for open quantum systems, are required. This is particularly true if one takes into consideration the current trends, towards extended systems such as large molecules [156][157][158][159] and nanostructures [160,161], for which overcoming decoherence, quantifying entanglement and non-classical behavior, and controlling the coupling with the environment will pose major challenges. The present review is a brief illustration of how phase-space tools widely used in quantum optics, such as quasiprobability densities, may be employed in attosecond physics.…”