Semiconductor lasers and optical feedback

Summary Experimental work and theoretical discussion on microscopic processes and device behaviours are presented. The presence of optical feedback from the environment induces asymmetries in the system affecting practical use. Relevant microscopic mechanisms and their influence on laser system performances are discussed qualitatively and quantitatively. A comparison with standard models is performed. The authors of this paper have agreed to not receive the proofs for correction.     

On complex projective surfaces with trigonal hyperplane sections

Let S be a complex projective surface endowed with an ample and spanned line bundle L. Assume that (S,L) does not belong to some special classes and that c_l(L)²10. We prove that(K_SL)·K_S–3 and |L| contains a trigonal curve (of genus4) iff either (S,L) is a rational surface ruled by cubics, or the g¹ ₃ of C is cut out by |K_S ^–1|. This result applies to surface having a hyperplane section which is a trigonal curve.Partially supported by the M.P.I. of the Italian Government     

ALPs effective field theory and collider signatures

We study the leading effective interactions between the Standard Model fields and a generic singlet CP-odd (pseudo-) Goldstone boson. Two possible frameworks for electroweak symmetry breaking are considered: linear and non-linear. For the latter case, the basis of leading effective operators is determined and compared with that for the linear expansion. Associated phenomenological signals at colliders are explored for both scenarios, deriving new bounds and analyzing future prospects, including LHC and High Luminosity LHC sensitivities. Mono-Z, mono-W, W-photon plus missing energy and on-shell top final states are most promising signals expected in both frameworks. In addition, non-standard Higgs decays and mono-Higgs signatures are especially prominent and expected to be dominant in non-linear realisations.     

A classical hamiltonian method for calculating IR-Resonant photodesorption rates

Summary In this work, classical nonlinear dynamical methods are used to study photodesorption induced by IR-laser resonant excitation of an internal vibrational mode of a physisorbed molecule. Starting from the large disagreement between the experimental values of the photodesorption rates and the theoretical quantum perturbative ones for CH₃F/NaCl, the Elastic-Resonant-State Decay (ERSD) model is analysed focusing attention on the nonexponential time decay behaviour of the survival probability of the system, that shows two different time scales. This is obtained by a suitable average of classical trajectories calculated by integrating Hamilton’s equations of motion. The Poincaré sections are used to clarify the details of the microscopic dynamics of the IR-photodesorption, pointing out the dynamical role of cantori as responsible for desorption occurring on a longer time scale. A method to build up the separatrix for the ERSD system is proposed, stressing that such a separatrix acts as a bottleneck against the energy flux exchanged between the physisorption and the intramolecular bond of the adsorbate. A calculation of the photodesorption rate when a condition of fast relaxation between the two bonds is verified, is performed using the Transport Theory in Hamiltonian System. The values of the photodesorption rate obtained by this approach are in good agreement with those obtained by integrating numerically the equations of motion.     

Surface effects in the esterification of 9-pyrenebutyric acid within a glass micro reactor

Surface phenomena are an important contribution to the "chip effect", leading to higher yields and shorter reaction times, as demonstrated for the acid-catalysed esterification of 9-pyrenebutyric acid within a glass fabricated micro reactor.     

Miniaturized continuous flow reaction vessels: influence on chemical reactions

This review offers an overview of the relatively young research area of continuous flow lab-on-a-chip for synthetic applications. A short introduction on the basic aspects of lab-on-a-chip is given in the first part. Subsequently, the effects of downscaling reaction vessels as well as the advantages of the continuous flow microfluidic approach over conventional chemical laboratory batch methodologies are illustrated by a number of examples of organic reactions carried out in microfluidic devices. The last part deals with a key issue of the lab-on-a-chip approach, viz. the integration of the microreactor with the analytical instrumentation to achieve high-throughput reaction monitoring.