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The operational characteristics and imaging performance are described for a new instrument comprising an atomic force microscope coupled with a pulsed laser and a linear ion trap mass spectrometer. The operating mode of the atomic force microscope is used to produce topographic surface images having sub-micrometer spatial and height resolution. Spatially(More)
We report on the development of a versatile scanning apparatus for nanoscale surface sampling that utilizes the interaction of laser radiation at a sharp probe tip to effect desorption/ablation on opaque substrates. The process, which currently yields surface craters as small as approximately 50 nm diameterx5 nm deep, has been demonstrated with both(More)
Nine laboratories participated in a collaborative study of a method for determining 6 nitrosamines, dimethylnitrosamine, diethylnitrosamine, dibutylnitrosamine, nitrosopiperidine, nitrosopyrrolidine, and nitrosomorpholine, in the 5-17 ppb range. The coefficients of variation for repeatability were 10.8, 8.5, 10.4, 8.5, 8.7, and 7.8% with corresponding(More)
Ultrafast spectroscopy is dominated by time domain methods such as pump-probe and, more recently, 2D-IR spectroscopies. In this paper, we demonstrate that a mixed frequency/time domain ultrafast four wave mixing (FWM) approach not only provides similar capabilities, but it also provides optical analogues of multiple- and zero-quantum heteronuclear nuclear(More)
We present theoretical and experimental studies on the optical properties of dimers composed of octahedron-shaped, gold nanoparticles. The experimental measurements show that the photoluminescence varies quite dramatically as two octahedra are brought into close proximity. AFM images and optical emission have been recorded for dimers in uncoupled and(More)
A dual function atomic force/near-field scanning optical microscope (AFM/NSOM) with an ultrafast laser excitation source was used to investigate apertureless, tip enhanced second-harmonic generation (SHG) of ZnO nanowires with spatial resolution below the optical diffraction limit. Single-wire SHG spectra show little to no contribution from bandgap or other(More)
Optical spectra and atomic force microscopy (AFM) images of individually selected spheres and mechanically assembled silica-coated gold nanosphere pairs were recorded. The shell served as a means of rigid control of the minimum spacing between the metal cores. The spectra of the assembled spheres were simulated using classical electrodynamics. The observed(More)