The research in the Amitay group focuses on the creation of a new type of photochemistry that is based on ultrafast spectroscopy and quantum coherent control using shaped femtosecond pulses. The Amitay laboratory is equipped with state-of-the-art femtosecond laser systems, and combines ultrafast laser and optical techniques with spectroscopy and vacuum tools.
Organosilicon Chemistry, Organic chemistry and computational chemistry
Organosilicon Chemistry: Multiple bonds in silicon; polysilanes, silylenes and silicenium ions; enzymatic reactions of organosilicon compounds.
Organic Reaction Mechanisms: Reactive intermediates, in particular carbenium ions; strained molecules.
Computational Chemistry: Application of theory, in particular ab initio quantum mechanical methods, to organic chemistry, organometallic chemistry and bio organic molecules; molecular modeling.
Research in our laboratory encompasses a variety of projects directed toward development of new chemical and enzymatic strategies for the synthesis of biologically active compounds and designed molecules as mechanistic probes for enzymatic reactions, carbohydrate-mediated biological recognition and catalysis. The group has a tight collaboration with specialized laboratories in the fields of protein engineering, rapid-quench kinetics, solid-state NMR and protein crystallography. Current research areas include: · Rational design of novel antibacterial drugs · Design, synthesis and evaluation of catalytic oligosaccharides · Development of new synthetic methodologies, chemical and enzymetic, for the assembly of oligosaccharides
Our research group is developing novel synthetic approaches to chemically synthesize homogenous posttranslationally modified proteins, such as ubiquitinated and phosphorylated proteins, for structural, biochemical, biophysical and functional analyses.
Solid-state and solution supramolecular chemistry.
• Fabrication of nanometer-scale electronic components using self-assembly processes. • Site effects on chemical and physical properties of materials. • Structure - activity correlation in organic functional materials. Optical and electrical properties of organic functional materials.
Fundamental electrochemistry and materials chemistry for energy storage.
Graphitic carbons with complex architectures and multi-doped active sites.
Electrocatalysis in fuel cells, particularly oxygen reduction reaction and oxidation of alternative fuels.
The research in our group is focused on the rational design of new corrole complexes for multiple purposes. After tuning their chemical and photophysical properties by selective synthesis protocols that we devise, the corrole derivatives are introduced as key elements for a variety of applications: catalysis, small molecule activation, catalytic oxidation/reduction of water, drug development, and more.
· Molecular beam scattering: The study of interaction of hyperthermal (1-100 eV) molecular, atomic and cluster beams with single crystal surfaces under Ultra-High-Vacuum conditions. The research is aimed at investigating the dynamics of both impulsive scattering and trapping desorption processes at surfaces. · Molecular beam Eley-Rideal type chemistry: Single collision chemistry. Atom pick-up reactions and charge exchange. · Epitaxial growth and etching processes of thin films: Effusive growth from High-Temperature Knudsen cells and kinetic energy activated growth from molecular and cluster beams. · Decay processes of isolated superheated C60 molecule in beams: Unimolecular fragmentation via Time-of-Flight technique and radiative cooling. · Studies of fullerenes excitations: Plasmonic excitations in thin films using Electron Energy Loss (EEL) and X-ray photoemission (XPS) methods. · Strong technological orientation: Continuous development of new techniques and devices for detection and generation of molecular beams, High Vacuum and high temperature components.
Nanoscience and nanotechnology; Synthesis, structural and physical characterizations of II-VI and IV-VI quantum dot, rots, wires and platelets, core/shell derivatives, magnetically doped nanostructures, perovskites and single slabs of transition metal chalcogenides; Optical, magneto-optical characterization of ensemble and single nanostructures; Implementation as Q-switches, lasers, solar cells and biological devices.
Research in my lab is focused on biomimetic chemistry and metal coordination aiming to emulate the structure and function of metalloproteins including selective recognition, cooperative catalysis, electro- and photocatalytic water splitting, and self-assembly.
New methods for fast analysis of particulate materials Fast analysis of particulate materials represents one of the most challenging issues at the forefront of current analytical chemistry. The ability to rapidly analyze particulate materials, including aerosols, hydrosols and soils, may have far-reaching consequences and impact on the environmental sciences, on industrial process control, and on human health. Although analysis of particulate materials has been a long desired goal, it could not be achieved satisfactorily by most of the previously known methods. It is therefore necessary to develop novel strategies and methodological approaches for solving intrinsic problems. The new methods recently developed by Schechter's group for this specific purpose include Fourier Transform (FT) Chemical Imaging, Modified Laser Induced Breakdown Spectroscopy, Laser Multiphoton Ionization, Laser Induced Fluorescence and Cavity Ringdown Spectroscopy. The Schechter group at the Technion has been studying these approaches as well as their combinations for specific tasks. Furthermore, they have also developed analytical sampling methods that are suitable for particulate materials, and methods for sophisticated chemometric data analysis.
Solid state NMR techniques as molecular-functional eyes of materials interfaces and surfaces:
Bioorganic-inorganic interfaces in biomineralization and biomimetics; understanding function-tailored materials properties (biogenic and synthetic).
Specific binding by inorganic and organic mesoporous materials; understanding the molecular details that govern determine reactivity.
Biomedical Applications of Lasers - Photodynamic therapy (PDT) as a new modality for cancer treatment is studied in solutions, in cell suspensions and in-vivo. - Photosensitizing drugs (porphyrins, porphycenes and phthalocyanines) are graded according to their efficiency to generate singlet oxygen, the phototoxic intermediary. Changes in the triplet lifetimes of the sensitizers are measured as a function of oxygen content in different environments. - Binding of photosensitizers to erythrocytes and to liposomes, differing in composition and surface charge, are studied by absorbance and fluorescence spectroscopy. - The efficiency of oxidative damage, induced by PDT in erythrocytes, liposomes and various tumor cell lines, is monitored electrochemically in real time by the depletion of ambient oxygen. - Structure-activity relationships for different photosensitizers are derived from the correlation between the efficiency of a sensitizer and its 3-dimensional structure. - Novel photosensitizers for PDT are evaluated in-vivo using the chick chorioallantoic membrane (CAM) model. Video microscopy in real time serves to monitor the entire process of tumor growth, DT and tumor regression. Computerized image analysis is used to quantify occlusion of blood vessels nourishing the tumors, and the morphological modifications associated with vasoconstriction, as well as the resulting tumor necrosis.
The Physical Chemistry of Liquid Crystalline Systems - Nuclear magnetic resonance of liquids and liquid crystals. Molecular reorientations and other dynamic processes in liquids. - Nuclear quadrupole coupling constants of deuterium, nitrogen, oxygen and sulfur in small molecules. - The phase diagrams of lyotropic and thermotropic liquid crystals. The structure of liquid crystalline phases. Aliphatic chain and polar-head dynamics in non-ionic liquid crystals. Carbohydrate liquid crystals. alpha,omega-dicarboxylic acids lyotropic liquid crystals. - The properties of the liquid crystalline and gel phases of poly- gamma-benzyl-L-glutamate (PBLG) in different organic solvents. - Application of PBLG-organic solvent liquid crystals to the observation of chiral and prochiral enantiomers by NMR. - The study of the liquid crystalline phases of organic dyes (e.g. benzopurpurin in water) by NMR, X-rays, DSC and optical microscopy.
Organic Mass Spectrometry - Ion chemistry of organic gas-phase ions. - Stereochemical effects in the fragmentation of gas-phase ions. - Mechanistic studies of dissociation processes of gas-phase ions.Structural studies by mass spectrometry
The discovery of novel phenomena in atomic, molecular, mesoscopic, and biochemical systems which interact with light that is hard to predict and explain by using the standard formalism of quantum mechanics. In particular to show how decaying processes and interaction with the environment that introduce dephasing, dissipation and relaxation processes play key roles in introducing time asymmetric dynamics which are very robust and stable against small external perturbations.
General theory of nonadiabatic transitions: multi-state semiclassical approach, analytical models, surface hopping approach, transitions near the conical intersections.
Quasiclassical theory of inelastic collisions: eikonal approximation beyond the common trajectory approach, semiclassical description of polarization phenomena and charge transfer. Vibrational and electronic energy transfer in molecular collisions.
Quantum theory of inelastic collisions at low and ultra-low energies. Application to the vibrational relaxation of molecules in collisions with atoms in the Bethe-Wigner regime.
Stochastic approach to the intramolecular energy redistribution: diffusion across the energy space in the chaotic regions of molecular phase space, master equation and discrete Markov chain equation. Application to the vibrational predissociation.
Statistical and dynamical description of the complex formation and decay: incorporation of nonadiabatic effects into the adiabatic channel model of unimolecular reactions, formulation of the capture theory in the axially-nonadiabatic channel basis, application to the complex formation at low and ultra-low energies.
Theory of electron attachment/detachment to/from polyatomic molecules. Generalization of the Vogt-Wannier and zero-range potential models.
Molecular Dynamics: Energy Transfer · Supercollisions: Collisions that transfer an inordinately large quantity of energy per a single collision are called supercollisions. They were first found experimentally by us in 1988 and theoretical work has since continued on the subject. The effect of a minor fraction of supercollisions on the rates of chemical reactions is evaluated and their contribution to the overall average energy transfer is calculated. · Trajectory calculations: Classical trajectory calculations of collisions between bath atoms and molecules and highly excited polyatomic molecules are performed. Using ab initio and assumed inter- and intramolecular potentials, average energy transferred per collision quantities and collisional energy transfer probability density functions are calculated for an assortment of polyatomic-monatomic and polyatomic-polyatomic systems and a variety of initial conditions. · Cluster dissociations: The dynamics of large molecules with up to 1000 internal modes, as well as cluster dissociation are studied for a variety of initial conditions.
Physical Chemistry, Solid StateMolecular spectroscopy of organic molecules in condensed phases: single crystals, solutions, molecules imbedded in rare gas matrixes and adsorbed molecules on surfaces. Spectroscopic studies of semiconductors and their quantum structures.Study of the elementary excitations: excitons, phonons, their dynamics and the interaction between them. Experimental techniques: luminescence, excitation spectra, resonance Raman, Raman excitation profile, microwave modulated spectroscopy and time-resolved spectroscopy. All measurements are carried out at cryogenic temperatures.