This PDF file contains the front matter associated with SPIE Proceedings Volume 8245, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

We introduce the possibility of performing two-pulse correlation measurements in order to probe the dynamics of twophoton photoluminescence in Au nanostructures. Our preliminary results obtained from single-crystal Au nanorods are consistent with the two-step model for the photoluminescence process.

In this contribution we present surface enhanced Raman scattering (SERS) measurements of pyrene as a function of the surface plasmon resonance position of noble metal nanoparticle ensembles, which served as SERS substrates. The noble metal nanoparticle ensembles were prepared under ultrahigh vacuum (UHV) conditions by Volmer-Weber growth on quartz substrates. For the SERS measurements, the substrates were mounted in a flow-through cell as part of the optical Raman set-up. A diode laser microsystem with an emission wavelength of 488 nm was used. The system generates two slightly different emission wavelengths (Δλ ≈ 0.3 nm) with a spectral width of ≈ 10 pm and an optical power of ≈ 10 mW. With this set-up SERS as well as shifted excitation Raman difference spectroscopy (SERDS) can be carried out. For trace analysis of pyrene in water SERS/SERDS experiments were accomplished as a function of molecule concentration and spectral position of the plasmon resonance. The best results with a limit of detection of 2 nmol of pyrene were obtained with a nanoparticle ensemble with a plasmon resonance in the vicinity of the excitation wavelength of λ = 488 nm. If the plasmon resonance frequency is slightly off-resonance the detection limit is significantly lower. The latter results are discussed in more detail and we will demonstrate that the morphology and the optical properties of the SERS substrates crucially influence the LOD.

We present femtosecond laser induced photobleaching of individually isolated single-wall carbon nanotubes. Monodispersed single-wall carbon nanotubes fixed in aqueous gel were exposed under tightly focused femtosecond laser light. We measured photoluminescence spectra of single-wall carbon nanotubes before/after the laser irradiation. Because of unique excitonic band structures of single-wall carbon nanotubes, we clearly observed strong selectivity in the chirality and the orientation of carbon nanotubes depending on the wavelength and polarization of laser light. We also observed the difference from the case of continuous wave laser irradiation in the chirality selectivity and the efficiency of photobleaching.

Excimer lasers, due to their compatibility with a large-scale industrial production, are attractive tools for precise processing of photonic and microelectronic materials. In this article, we discuss the effect of ArF excimer laser defect formation on the surface of InP/InGaAs/InGaAsP quantum well (QW) microstructures irradiated in air and deionized (DI) water environments. Structural defects on surfaces of such QW materials have been known to induce vacancy diffusion towards the QW region and lead to the so called quantum well intermixing (QWI) effect during the rapid thermal annealing step. Excimer lasers have been used to create surface defects on InP/InGaAs/InGaAsP microstructure and induce QWI during high temperature annealing. Chemical composition of the QW microstructures irradiated with ArF laser in air and DI water is studied with X-ray photoelectron spectroscopy to investigate both the formation and role of the surface defects in the laser-induced QWI process.

Zinc oxide is a wide bandgap insulator with significant promise for applications in optics, electro-optics and electronics. However, there are challenges in growing high-quality material, and a prominent visible luminescence channel due to defect recombination competes with the ultraviolet band-edge exciton decay. Here we demonstrate the possibility of characterizing a specific defect by means of Purcell enhanced exciton-plasmon dynamics and photoluminescence.

We report the fabrication of PbTe quantum dots grown under inert gas (Ar and He) atmosphere by pulsed laser deposition using the second harmonic of a Q-Switched Quantel Nd:YAG laser. For characterization, samples were prepared onto a 40Å carbon film deposited on a copper grid. The influence of background pressure, and number of laser pulses on the size distribution of the PbTe nanoparticles was investigated by transmission electron microscopy using a 200 kV TECNAI G2 F20 electron microscope with 0.27 nm point resolution. The size distribution was obtained by manually outlining the particles from several dozens of low- and high-resolution TEM images. Once digitized and saved in a proper format, the image was processed using the J-image software. Characterizations reveal an increase of the nanoparticle size both with the amount of material deposited (number of laser pulses) and the background pressure. Furthermore, measurements reveal a narrower nanoparticle size distribution by increasing the number of laser pulses or by decreasing the background pressure. HRTEM studies of the influence of different ambient gases on the structural properties of the PbTe nanoparticles are being conducted.

In this paper we report the fabrication of nanoparticles and nanostructures through the interaction of ultrashort (~40 fs) and short (~2 ps) laser pulses with bulk Aluminum immersed in various liquid media of different polarity [chloroform which is polar, carbon tetrachloride which is non-polar, water which is polar, dichloromethane (DCM) which is polar, and Cyclohexane which is non-polar] using the laser ablation technique. Except water and Cyclohexane, other media showed yellow coloration after ablation took place indicating formation of nanoparticles in the solution in both fs and ps domains. The coloration of the laser exposed portion in the Al substrate was golden yellow and its closer view depicted micro-grating (~1-2 μm) and nano-ripple (period 330 nm) formation depending on the focal conditions. The investigation of polarization dependence on the ablation was performed for water media. Depending on the ablation threshold, we observed micron sized structures and nano-ripples on the surface. As the rate of ablation depends on the position of the focus on the Al substrate and beam waist parameters, we have studied the liquid level dependence of ablation with different water levels on the Al substrate and we compared these patterns obtained below, near, and above the ablation thresholds of the sample. Field Emission-Scanning Electron Microscope (FE-SEM), UV-Vis absorption spectra, Electron Diffraction Pattern and Transmission Electron Microscope (TEM) were used for the characterization and comparison of products in both domains.

We have succeeded in growing various ZnO nanocrystals, such as nanowires, nanorods, and nanowalls, by a nanoparticle-assisted pulsed-laser deposition (NAPLD). In this study, low-density ZnO nanowires were synthesized by introduction of a ZnO buffer layer. Low-density hexagonal cone-shape ZnO cores are formed on the buffer layer, and vertically-aligned ZnO nanowires are grown on the cores. The density of the nanowires was clearly decreased with increasing the thickness of the Buffer layer. The buffer layer can be used as one of the effective additives to control the growth density of the ZnO nano-crystals synthesized by NAPLD.

High-intensity high-order harmonics have been investigated intensively in recent years. In the development of a beam line for the high-intensity high-order harmonics, however, utilizing a conventional beam splitter (BS) (Si or SiC) that absorbs the fundamental waves has caused serious problems such as its thermal distortion. To solve these problems, we proposed and investigated a novel BS with transparent materials that transmitted the fundamental waves and then reflected the high-order harmonics. In BS for the high-order harmonics, reflection of the fundamental waves should be minimized by entering the p-polarized fundamental waves at the Brewster's angle, which could improve the separation between the fundamental waves and the high-order harmonics at the same Brewster's angle. We have already investigated and fabricated WO₃/TiO₂ bilayers on c-plane sapphire substrates by controlled growth with sequential surface chemical reactions (SSCR) using sequentially fast pressurized pulses of the vapor sources. Our previous experimental results revealed that WO₃ (221) and rutile TiO₂ (200) thin films could be grown epitaxially on c-plane sapphire substrates by SSCRs. Then, in this study, we proposed a WO₃/TiO₂ bilayer grown on c-plane sapphire substrates, which could be utilized as a BS for the high-order harmonics. Reflectance characteristics were also investigated at the same Brewster's angle using monochromatized synchrotron radiation (SR) located at Ultraviolet Synchrotron Radiation Facility (UVSOR), Institute for Molecular Science, Okazaki, Japan.