לוח שנה משולב

I discuss the recent theoretical prediction and the experimental confirmation by LHCb of an exotic baryon which contains five quarks, including hidden charm. This discovery can best be understood in the context of earlier discoveries of doubly heavy exotic mesons. When viewed this way, the discov-ery of the new exotic baryon strongly suggest existence of many more analogous exotic states, with both charmed and bottom quarks. Specific predictions are given for masses and decay modes
of these states, as well as possible ways to observe them in experiments.

In this seminar, I will introduce the fundamentals of guided optics. A brief overview will be given over design, fabrication and characterization of integrated optical components and microfluidic channels. I will focus on the conceptual importance of the integrated optics and surface modification for chemo- and bio-applications. The potential of disorder-enhanced photonics in vibrational spectroscopy on waveguides will be discussed and new directions will be proposed. Vibrational spectroscopy relies on absorption of electromagnetic radiation by molecular vibrations. It is a powerful tool for drawing information on molecular structure and dynamics. In the first part of the talk I will present an intriguing physical effect of disorder-enhanced absorption of light by molecular overtones of amines in a: 1) silicate channel waveguide and 2) microtapered fiber with adsorbed gold nanoparticles. Due to the guides’ surface modification, aromatic rings tend to stack together, and N-H bonds in amines form hydrogen bonds with each other. This 8 nm thick multilayer structure of lamellar liquid crystal shape leads to the switch from ballistic to diffusive propagation of light which results in the enhanced absorption. I will also address a dynamics of absorption as a function of time of adsorption of the organic molecules on waveguide. These phenomena are expected to find application in organic solution based optical sensors for detection of explosive materials and diagnostics of psychoactive stimulants based on amines. In the second part of the talk, I will present a theoretical study of composite plasmonic waveguide structures for design of integrated optical components and Purcell enhanced chemiluminescence in a microfluidic channel.