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Full-Text Articles in Physics
Single Molecule Emission Characteristics In Near-Field Microscopy, Randy X. Bian, Robert C. Dunn, X. Sunney Xie, P.T. Leung
Single Molecule Emission Characteristics In Near-Field Microscopy, Randy X. Bian, Robert C. Dunn, X. Sunney Xie, P.T. Leung
Physics Faculty Publications and Presentations
In near-field scanning optical microscopy (NSOM), the measured fluorescence lifetime of a single dye molecule can be shortened or lengthened, sensitively dependent on the relative position between the molecule and aluminum coated fiber tip. The modified lifetimes and other emission characteristics are simulated by solving Maxwell equations with the finite-difference time-domain (FDTD) method. The 2D computation reveals insight into the lifetime behaviors and provides guidance for nonperturbative spectroscopic measurements with NSOM. This new methodology is capable of predicting molecular emission properties in front of a metal/dielectric interface of arbitrary geometry.
Doubled Co2 Experiments With The Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model, R. M. Mackay, M. A. K. Khalil
Doubled Co2 Experiments With The Global Change Research Center Two-Dimensional Statistical Dynamical Climate Model, R. M. Mackay, M. A. K. Khalil
Physics Faculty Publications and Presentations
The zonally averaged response of the Global Change Research Center two-dimensional statistical dynamical climate model (GCRC 2-D SDCM) to a doubling of atmospheric carbon dioxide (350 parts per million by volume (ppmv) to 700 ppmv) is reported. The model solves the two-dimensional primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables: zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p=rhoRT, and …
Origins And Effects Of Thermal Processes On Near-Field Optical Probes, Andres H. La Rosa, B. I. Yakobson, H. D. Hallen
Origins And Effects Of Thermal Processes On Near-Field Optical Probes, Andres H. La Rosa, B. I. Yakobson, H. D. Hallen
Physics Faculty Publications and Presentations
An aluminum-coated tapered fiber probe, as used in near-field scanning optical microscopy (NSOM), is heated by the light coupled into it. This can destroy the probe or may modify the sample, which can be problematic or used as a tool. To study these thermal effects, we couple modulated visible light of various power through probes. Simultaneously coupled infrared light senses the thermal effects. We report their magnitude, their spatial and temporal scales, and real-time probe damage observations.Amodel describes the experimental data, the mechanisms for induced IR variation, and their relative importance.
Ionization-Excitation Of Helium By Fast Charged Particles, L. Nagy, J. Wang, Jack C. Straton, James H. Mcguire
Ionization-Excitation Of Helium By Fast Charged Particles, L. Nagy, J. Wang, Jack C. Straton, James H. Mcguire
Physics Faculty Publications and Presentations
Probabilities and cross sections for ionization plus excitation in helium produced by fast heavy-particle impact have been evaluated. In these calculations, contributions from shake-off, time ordering, and independent interactions of the frozen-target electrons with the projectile are included. A comparison is made to recent experimental observations for the ratio of excitation-ionization to single-ionization total cross sections. A comparison is also made to calculations of excitation-ionization by fast electron impact.
Molecular Fluorescence Spectroscopy In The Vicinity Of A Microstructure, P.T. Leung, Thomas F. George
Molecular Fluorescence Spectroscopy In The Vicinity Of A Microstructure, P.T. Leung, Thomas F. George
Physics Faculty Publications and Presentations
A brief review is presented on fluorescence spectroscopy of molecules in the vicinity of a microstructure, which could be a surface structure, clustered ions/atoms, a colloidal particle in a solution, or a tip in certain molecular probes. This structure can be viewed as microscopic, mesoscopic or macroscopic, depending on the specific environment in which the molecule is located. An overview is given for selected experimental and theoretical aspects of this phenomenon, emphasizing some of the previous modeling work of the authors. Discussion of possible future attempts to explore the phenomenon in more detail is presented at the end.