Koen Clays

Bio: Koen Clays is an academic researcher from Katholieke Universiteit Leuven. The author has contributed to research in topics: Hyperpolarizability & Rayleigh scattering. The author has an hindex of 60, co-authored 378 publications receiving 13317 citations. Previous affiliations of Koen Clays include Chinese Academy of Sciences & University of Pennsylvania.

Hyper-Rayleigh scattering in solution.

Abstract: Hyper-Rayleigh scattering in solution is used for the determination of the hyperpolarizability of nonlinear optical molecules. Obtaining the first hyperpolarizability \ensuremath{\beta} without having to independently determine the dipole moment \ensuremath{\mu} and the second hyperpolarizability \ensuremath{\gamma} is an advantage over the electric-field-induced second-harmonic generation technique. Values of the first hyperpolarizability \ensuremath{\beta} of 23\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}30}$ esu for para-nitroaniline, 105\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}30}$ esu for 4-methoxy-4'-nitrostilbene, and 95\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}30}$ esu for 4-hydroxy-4'-nitrostilbene dissolved in chloroform have been obtained. The equivalent-internal-field model is shown to hold for small saturated molecules.

Second-order nonlinear optical materials: recent advances in chromophore design

Abstract: This paper deals with recent and important developments in the field of organic materials for second-order nonlinear optics. Attention is drawn to current trends in chromophore design with a discussion of current progress and problems in this field. A number of important classes of chromophores, such as one-dimensional charge-transfer molecules, octopolar compounds, ionic materials, multichromophore systems and organometallics, are discussed.

Hyper‐Rayleigh scattering in solution

Abstract: The experimental setup for the implementation of a new technique to determine the hyperpolarizability of nonlinear optical molecules in solution is presented The new technique, hyper‐Rayleigh scattering in solution [K Clays and A Persoons, Phys Rev Lett 66, 2980 (1991)], has the advantage over the electric‐field‐induced second‐harmonic generation technique that the dipole moment μ and the second hyperpolarizability γ do not have to be independently determined to obtain the first hyperpolarizability β No electric field is needed to lower the intrinsic symmetry of the isotropic solution, leading to a simpler cell design and a simpler local field factor The internal reference method, when applicable, completely eliminates the local field factor With the technique presented, values of the first hyperpolarizability β of 23×10−30 esu for para‐nitroaniline (PNA), 105×10−30 esu for 4‐methoxy‐4’‐nitrostilbene (MONS), and 95×10−30 esu for 4‐hydroxy‐4’‐nitrostilbene (HONS) dissolved in chloroform have been obtained

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

Abstract: 3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

Orbital angular momentum: origins, behavior and applications

Abstract: As they travel through space, some light beams rotate. Such light beams have angular momentum. There are two particularly important ways in which a light beam can rotate: if every polarization vector rotates, the light has spin; if the phase structure rotates, the light has orbital angular momentum (OAM), which can be many times greater than the spin. Only in the past 20 years has it been realized that beams carrying OAM, which have an optical vortex along the axis, can be easily made in the laboratory. These light beams are able to spin microscopic objects, give rise to rotational frequency shifts, create new forms of imaging systems, and behave within nonlinear material to give new insights into quantum optics.

Directed Self-Assembly of Nanoparticles

Abstract: Within the field of nanotechnology, nanoparticles are one of the most prominent and promising candidates for technological applications. Self-assembly of nanoparticles has been identified as an important process where the building blocks spontaneously organize into ordered structures by thermodynamic and other constraints. However, in order to successfully exploit nanoparticle self-assembly in technological applications and to ensure efficient scale-up, a high level of direction and control is required. The present review critically investigates to what extent self-assembly can be directed, enhanced, or controlled by either changing the energy or entropy landscapes, using templates or applying external fields.