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.

Investigation of terahertz vibration-rotation tunneling spectra for the water octamer.

Abstract: We report a combined theoretical and experimental study of the water octamer-h16. The calculations used the ring-polymer instanton method to compute tunnelling paths and splittings in full dimensionality. The experiments measured extensive high resolution spectra near 1.4 THz, for which isotope dilution experiments and group theoretical analysis support assignment to the octamer. Transitions appear as singlets, consistent with the instanton paths, which involve the breakage of two hydrogen-bonds and thus give tunneling splittings below experimental resolution.

The C9 cluster: structure and infrared frequencies.

Abstract: The high resolution infrared spectrum of the C9 cluster has been measured in direct absorption by infrared diode laser spectroscopy of a pulsed supersonic carbon cluster jet. Fifty‐one rovibrational transitions have been assigned to the ν6 (σu ) antisymmetric stretch fundamental of the 1Σ+9 linear ground state of C9. The measured rotational constant [429.30(50) MHz] is in good agreement with ab initio calculations and indicates an effective bond length of 1.278 68(75) A, consistent with cumulenic bonding in this cluster. Several perturbations are observed in the upper state, and the upper‐ and lower‐state centrifugal distortion constants are observed to be anomolously large, evidencing a high degree of Coriolis mixing of the normal modes.

Determination of the dipole moment of ArH+ from the rotational Zeeman effect by tunable far infrared laser spectroscopy.

Abstract: The first determination of the electric dipole moment of a molecular ion is reported. A tunable far-infrared laser was used to measure the Zeeman effect in low-J rotational transitions of ArH+ and ArD+, and the dipole was determined from the isotopic dependence of gr. The result (μ=1.4±0.4 D) is in marginal agreement with ab initio calculations (2.2 D). It is shown that this method can ultimately provide molecular-ion dipole moments accurate to within a few percent. The adiabatic internuclear separations of both isotopes were also determined from the gr values.

A study of the structure and dynamics of the hydronium ion by high resolution infrared laser spectroscopy. II. The ν4 perpendicular bending mode of H3 16O

Abstract: Sixty‐six lines in the ν4 band of H3O+ have been measured using diode laser velocity modulation spectroscopy. 36 have been assigned to the a–a component of the spectrum and 30 to the s–s component. The observed spectra were fit to a standard symmetric top Hamiltonian including the effects of l‐type doubling. The band origin of the s–s transitions is at 1625.947(5) cm−1, whereas that of the a–a component lies at 1638.533(3) cm−1. The effect of the asymmetric bending vibration on the inversion splitting is in qualitative agreement with previous theoretical results, but the experimental band origins deviate by about 60 cm−1 from calculated values. Coriolis perturbations are found to have an important effect on the rotational constants of the ν4 and ν2 levels.

Infrared laser spectroscopy of molecular ions.

Abstract: The development of new techniques for infrared laser spectroscopy of molecular ions has resulted in an explosion of high-quality data for important charged molecules. Velocity modulation laser spectroscopy, which exploits the motions of charged particles in electrical plasmas to eliminate interference from neutral absorbers, is rapidly producing a large body of new results for both positive and negative molecular ions. This information will have an important impact on chemistry, biology, and astrophysics. 26 references, 2 figures.

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.