Richard J. Saykally

Bio: Richard J. Saykally is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Spectroscopy & Absorption spectroscopy. The author has an hindex of 94, co-authored 457 publications receiving 40997 citations. Previous affiliations of Richard J. Saykally include University of California & Lawrence Berkeley National Laboratory.

Single nanowire waveguides and lasers

Abstract: Quasi one-dimensional nanostructures are unique probes of cavity quantum electrodynamics because they are capable of exhibiting photonic and/or electronic confinement in two dimensions. The near-cylindrical geometry and sharp end facets of zinc oxide (ZnO) nanowires enable the realization of active nanoscale optical cavities that exhibit UV/blue photoluminescence (PL) waveguiding and lasing action at room temperature under appropriate optical pumping conditions. Study of individual nanostructures is crucial for isolating geometry-dependent effects, and here it is achieved through both near- and far-field microscopies. The polarization of the emitted PL or lasing from individual nanostructures characterizes the coupling of the spontaneous emission to cavity modes, depending both on the wavelength of the emitted light and the nature of the emitting species (i.e., excitons and intrinsic defects in various charge states). In addition, the spectral evolution of the lasing/PL as a function of the pump fluence indicates both exciton and electron-hole plasma dynamics. Variations of size, geometry, and material on the prototypical cylindrical ZnO nanowire lead to further observation of unique photonic and/or carrier confinement effects in novel nanostructures.

Rotation-tunneling spectrum of the deuterated ammonia dimer

Abstract: The millimeter and submillimeter-wave molecular-beam spectrum of the perdeuterated ammonia dimer (ND3)2 has been measured between approximately 50 and 400 GHz using an electric-resonance optothermal spectrometer (EROS). As in the case of the (NH3)2, the spectrum is complicated by the threefold internal rotation of the ND3 subunits, the interchange tunneling of the two subunits, and the inversion of the subunits through their respective centers of masses. These tunneling motions split the rigid-molecule energy levels into 22 components, which all have nonzero statistical weights in the case of the deuterated dimer. Transitions have been assigned for rotation-tunneling states correlating to A–A (ortho–ortho) combinations of the ND3 monomer states, where A designates the rovibronic symmetries of the ND3 subunits. One K=1←1, one K=1←0, one K=0←1, and two K=0←0 progressions have been assigned. The data have been fit to 0.28 MHz using linear molecule-type energy-level expressions to determine rotational constan...

Precise measurement of the J=2←1 fine structure interval in N(II) by far‐infrared laser magnetic resonance

Abstract: Far‐infrared laser magnetic resonance spectroscopy has been used to measure the J=2←1 fine structure intervals in the 3P ground states of singly ionized 14N and 15N atoms. In 14N(II) this separation is 2459.3703(14) GHz, and in 15N(II) it is 2459.3816(19) GHz. The hyperfine constants and gJ factors have been evaluated for both isotopes. Zero field energies for the hyperfine components of the J=2←1 transition in both isotopes are given in an effort to facilitate their observation in interstellar sources. A complete description of the hyperfine and Zeeman Hamiltonian matrix elements for atomic fine structure transitions is given in an LS coupled basis set.

Detection of the Linear Carbon Cluster C10: Rotationally Resolved Diode-Laser Spectroscopy

Abstract: Detected in interstellar space and as intermediates in soot formation, molecules of pure carbon in the form of linear chains or ring structures have interested researchers for several decades, who attempt to elucidate their physical properties and the processes govering their formation. A high-resolution infrared spectrometer housing a tunable diode laser and combined with an effective laser ablation source for the cluster production has been used to study the molecular properties of small carbon clusters; reported herein is the first gas-phase spectrum of linear C10.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric Environment

Abstract: The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...

Dye-Sensitized Solar Cells

Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Abstract: Highly luminescent semiconductor quantum dots (zinc sulfide-capped cadmium selenide) have been covalently coupled to biomolecules for use in ultrasensitive biological detection. In comparison with organic dyes such as rhodamine, this class of luminescent labels is 20 times as bright, 100 times as stable against photobleaching, and one-third as wide in spectral linewidth. These nanometer-sized conjugates are water-soluble and biocompatible. Quantum dots that were labeled with the protein transferrin underwent receptor-mediated endocytosis in cultured HeLa cells, and those dots that were labeled with immunomolecules recognized specific antibodies or antigens.