The vacuum ultraviolet analytical spectrophotometer with photo luminescence (VUVAS+PLUS) emission spectrometer operates from at least from 140 to 2600 nanometers depending on the selected model; vacuum and atmospheric versions are available. It uses all reflective optics to collect fluorescent or luminescent emission at a ninety degree angle and deliver signal – free from chromatic aberration – to the entrance slit of the emission spectrometer. The emission spectrometer may be optimized to detect signals well into the infrared. Signal acquisition of the 400 to 800nm visible spectral region with resolution on order 0.2 nanometers full-width-half-maximum can occur in milliseconds using the charge-couple device (CCD) detector. Accessories for persistence measurements are available too.
The new VUVAS+PLUS Spectrophotometer system measures transmittance and reflectance at adjustable angles. Plus it delivers tunable vacuum ultraviolet (VUV) excitation light to samples with emission measured in the visible and near infrared. A high vacuum environment keeps samples clean and prevents absorption by atmospheric gases and water vapor. A liquid Helium cryostat allows cooling samples during measurements.
Abstract: Contactless measurements of water temperature are utilized in a number of sciences, such as oceanography, climatology, and biology. Previously reported Raman spectroscopy techniques exploited the changes in the shapes of water Raman bands. Interpretation of these changes is difficult since these bands are composed of multiple lines, each influenced not only by temperature but also by pressure and salinity. This paper presents a proof-of-principal demonstration of a contactless technique which determines water temperature from the ratio of Stokes and anti-Stokes intensities of the water 180 cm1 Raman band. This ratio is not sensitive to pressure and salinity, allowing reliable determination of water temperature.
S. P. Nikitin, C. Manka, J. Grun, and J. Bowles
Abstract: The luminous efficiency and lifetime of plasma display panels (PDPs) are directly related to the performance of phosphors used in PDPs, thus higher efficiency, higher stability against high temperature processes and a long lifetime along with good color chromaticity against vacuum-ultraviolet (VUV) radiation are major concerns in selecting suitable phosphors for PDPs. In the same pursuit, we have developed the nano-sized (15–40 nm) BAM:Eu2+, YAG:Tb3+ and YAG:Eu3+ as blue, green and red phosphors and studied their luminescence properties under VUV excitations. In BAM:Eu2+, the 5d-excitation of Eu2+ ions are found strongly dependent on the crystal field strength and Eu2+ occupy lattice ‘sites I’ by substituting Ba2+ ions. Whereas, in YAG:Tb3+, the observed green luminescence is assigned to 5D4?7Fj transitions (j = 3–6) due to electric dipole–dipole interaction, while, YAG:Eu3+ shows strong red luminescence corresponding to 5D0?7F2 transition. Time evolution studies along with decay time calculations are further employed to verify the sustainable emission without quenching.
Prashant K. Sharma, Ranu K. Dutta, Avinash C. Pandey
Abstract: Porous silicon samples have been prepared from p-type single-crystal silicon <100> by a galvanostatic and an open-circuit etch in 50% HF. The materials display bright red-orange room-temperature photoluminescence (PL) in air and toluene solution. Infrared measurements show that the porous silicon surface is partially oxidized. Exposure to anthracene (An) or 10-methylphenothiazine (MPTZ) results in dynamic quenching of the material's excited state(s). Nanosecond time-resolved PL decays are complex and wavelength dependent, with average lifetimes in neat toluene of 0.3-16 µs. Quenching by An and MPTZ is more efficient and rapid at short observation wavelengths. The steady-state and time-resolved quenching data are well fit to the Stern-Volmer model. The PL decays are well described by a skewed distribution of recombination rates.
Minh C. Ko and Gerald J. Meyer
Abstract: Discussed are the photoluminescence properties of combustion synthesized red and green emitting borate phosphors—YBO3 : Eu3+, BaZr(BO3)2 : Eu3+, YCaBO4 : Eu3+, YAl3(BO3)4 : Eu3+, YAl3(BO3)4 : Tb3+, LaBaB9O16 : Tb3+, LaBaB9O16 : (Ce3+,Tb3+), and Na3La2(BO3)3 : Tb3+-promising for use in plasma display panels and mercury-free fluorescent lamps.
P. A. Nagpure, S. K. Omanwar
Abstract: Coherent anti-Stokes Raman scattering (CARS) with femtosecond interaction pulses has become a popular and powerful spectroscopic method. Non-resonant background is one of the most limiting factors for implementing this method more widely. We propose a new approach that suppresses the non-resonant background contribution to the measured signal in CARS spectroscopy while simultaneously yielding high spectral resolution. The method is based on femtosecond pulse shaping of probe, Stokes and pump beams. Destructive interference suppresses the non-resonant background, resulting only in the resonant contribution being detected.
Stanislav O. Konorov, Michael W. Blades and Robin F. B. Turner
Abstract: We investigate the possibility of implementing coherent anti-Stokes Raman spectroscopy (CARS) with a single laser beam passed through a one-dimensional scattering object. The effect of the random scattering is emulated by shaping the laser pulses with a spectral mask corresponding to the transmission spectrum of a random layered medium. Raman resonances are retrieved through correlation analysis of the CARS spectrum. We study the effect of the scattering parameters on the resolution of the method, and show that improvement of the spectroscopic sensitivity can be achieved by compensating the phase distortions introduced by the scatterer
T.M. Drane, J.W. Hepburn and V. Milner