Background: Protein expression profiling for differences indicative of early cancer has promise for improving diagnostics. This report describes the first stage of a National Cancer Institute/Early Detection Research Network-sponsored multiinstitutional evaluation and validation of this approach for detection of prostate cancer. Methods: Two sequential experimental phases were conducted to establish interlaboratory calibration and standardization of the surface-enhanced laser desorption (SELDI) instrumental and assay platform output.

We investigated the effect of the excitation wavelength on the density evolution of laser-produced tin plasmas, both experimentally and numerically. For producing plasmas, Sn targets were excited with either 10.6 lm CO 2 laser or 1.06 lm Nd:yttrium aluminum garnet laser; both are considered to be potential excitation lasers for extreme ultraviolet lithography laser-produced plasma light sources. The electron density of the plasma during the isothermal expansion regime was estimated using an interferometric technique. The Stark broadening of isolated singly-ionized emission was employed for deducing the density during the plasma adiabatic expansion regime. Our results indicate that the excitation source wavelength determines the initial density of the plasma, as well the plume expansion dynamics. Numerical simulation using HEIGHTS simulation package agrees well with the experimentally measured density profile. V

We investigated the effects of laser wavelength on the atomic, ionic, and radiative emission from laser-produced tin plasmas. For generating plasmas, planar tin targets were excited using either high intensity neodymium-doped yttrium aluminum garnet ͑Nd:YAG, 1.06 m͒ or carbon dioxide ͑CO 2 , 10.6 m͒ laser pulses; both are considered to be potential excitation lasers for an extreme ultraviolet ͑EUV͒ lithography laser-produced plasma light source. Various diagnostic tools were utilized for investigating ionic, neutral, and radiative emission from Sn plasmas including Faraday cup, witness plate in conjunction with x-ray photoelectron spectroscopy ͑XPS͒, EUV, and visible emission spectroscopy and photography. Atomic and ionic analysis showed that the amount of debris emitted by the Nd:YAG generated plasmas was considerably higher than the CO 2 laser-produced plasmas. The angular distributions of both atomic and ionic debris were found to be more forward-centric for the 1.06 m generated plasma while being much more uniform for the 10.6 m heated plasma. EUV and visible emission images of the plasma also showed a forward-centric appearance for 1.06 m heated plasmas. The strength of excited neutral emission was considerably lower for the case of the 10.6 m plasma while the kinetic energies of ions debris were found to be much higher for CO 2 generated plasmas. Surface analysis of the craters created by the lasers showed that the mass ablation rate is 3.6 times higher for Nd:YAG laser generated plasmas compared to CO 2 generated plasmas at maximum EUV emission.

Tin and lithium plasmas emit efficiently in the in-band region ͑13.5 nm with 2% bandwidth͒ necessary for extreme ultraviolet ͑EUV͒ lithography. We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and Li plasmas under identical experimental conditions. Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy ͑OES͒, a Faraday cup, an EUV pinhole camera, the absolute measurement of EUV conversion efficiency ͑CE͒, etc. Our results show that Sn plasmas provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher, though with a lower flux. OES studies have showed that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species.

We investigated the effects of laser wavelength on atomic and ionic emission from Sn plasmas. Plasmas were produced using planar Sn targets excited with 10.6 μm carbon dioxide (CO2) and 1.06 μm neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Two-dimensional spectral imaging of visible emission showed that continuum emission was significantly more intense in the CO2 laser produced plasma (LPP) whereas line emission was considerably more extensive in the Nd:YAG LPP. Faraday cup analysis showed that ion profiles were narrower with CO2 LPPs although they possessed higher kinetic energies.