We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.

Using a flow-tube reactor coupled to a chemical ionization mass spectrometer, we investigated the heterogeneous loss of OH on Halocarbon wax, two types of organized organic monolayers, and several solid organic surfaces (paraffin wax, stearic acid-palmitic acid mixture, pyrene, and soot) that are representative of surfaces found in the troposphere. The heterogeneous reaction is very efficient: the reaction probability is greater than 0.1 for all the organic surfaces investigated, except for Halocarbon wax. These results indicate that OH-organic heterogeneous reactions will significantly modify the hygroscopic properties and cloud condensation nuclei (CCN) ability of organic surfaces in the troposphere, and thus may play an important role in the Earth's radiative balance by affecting the properties of clouds. We also determined the diffusion coefficient of OH in helium to be 665 ( 35 Torr cm 2 s -1 . This value is close to that of its polar analogue, H 2 O, suggesting that the diffusion coefficient of OH can be calculated accurately with H 2 O transport properties.

We show that the Raman scattering technique can give complete structural information for onedimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an ͑n, m͒ individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency v RBM and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d t , using the parameters g 0 2.9 eV and v RBM 248͞d t. For example, the strong RBM intensity observed at 156 cm 21 for 785 nm laser excitation is assigned to the ͑13, 10͒ metallic chiral nanotube on a Si͞SiO 2 surface.

In vitro experiments have demonstrated the ability of Raman spectroscopy to diagnose a wide variety of diseases. Recent in vivo investigations performed with optical fiber probes were promising but generally limited to easily accessible organs, often requiring relatively long collection times. We have implemented an optical design strategy to utilize system throughput fully by characterizing the Raman distribution from tissue. This scheme optimizes collection efficiency, minimizes noise, and has resulted in small-diameter, highly efficient Raman probes that are capable of collecting high-quality data in 1 s. Performance has been tested through simulations and experiments with tissue models and several in vitro tissue types, demonstrating that this new design can advance Raman spectroscopy as a clinically practical technique.

We report the first successful study of the use of Raman spectroscopy for quantitative, noninvasive ("transcutaneous") measurement of blood analytes, using glucose as an example. As an initial evaluation of the ability of Raman spectroscopy to measure glucose transcutaneously, we studied 17 healthy human subjects whose blood glucose levels were elevated over a period of 2-3 h using a standard glucose tolerance test protocol. During the test, 461 Raman spectra were collected transcutaneously along with glucose reference values provided by standard capillary blood analysis. A partial least squares calibration was created from the data from each subject and validated using leave-one-out cross validation. The mean absolute errors for each subject were 7.8%+/-1.8% (mean+/-std) with R2 values of 0.83+/-0.10. We provide spectral evidence that the glucose spectrum is an important part of the calibrations by analysis of the calibration regression vectors.