Jp Wu

CBRE · ISL Syngenta

Gaussian analysis of Raman spectroscopy reveals three significant structures in the liquid acetic acid (AA): linear chains involving C–H•••O═C and O–H•••O═C hydrogen bonding, cyclic dimers and dissociated monomers that can effectively cooperate with hydrogen bonded stacks of linear AA or polymer chains.

In this paper, the author reported two methods to extract spectral or spatial information inherited in the Raman chemical images for linear quantification calibration of crystallinity. The two approaches reported quantification results according to the spectral mean score of overall pixels or the spatial percentage of the pixels with a score greate...

It is common belief that in Raman mapping, the sampling depth from which Raman signal is collected originates from a probe laser spot size of approximately 1–5 µm3. Actually, the active pharmaceutical ingredient (API) crystals detected by mapping on the sample surface distribute from surface to over a few tens to hundreds of microns into the sample...

• Raman mapping • Advantage of Raman mapping in physical characterizations • Case studies

A large quantity of a sample is usually required in electrical conductivity measurements of fluids. If precise electrical conductivity measurements are to be performed while using small test samples, it is necessary to study the effects of both fringe electric fields and interfacial properties. These effects were investigated here by using a novel...

FTIR spectra become unfeasible for detecting some narrow bands from the background of a strong broad band. We present a general method for evaluating the narrow bands in FTIR spectra by using second derivatives. As demonstrated by a synthetic Gaussian type spectrum, such information as the peak position and intensity contained in those narrow bands...

We present a low-cost experimental method for measuring cell resistance and capacitance independently. In this technique a triangular waveform voltage excitation is adopted. Conductivity calibration is straightforward. However, it is demonstrated that a specific calibration procedure needs to be followed to obtain correct relative permittivity valu...

The temperature dependence of the photoluminescence (PL) and infrared stimulated luminescence (ISL) exhibited by CaS doped with both europium (Eu) and samarium (Sm) ions is reported for temperatures in the range between 100 and 700 K. Behavior indicative of strong electron-phonon coupling is observed in the PL emission of the Eu2+ ion and two proce...

We present a novel low-cost experimental method for measuring the electrical conductivity and relative permittivity of liquids at low frequencies. Based on the different relationship between the resistive and capacitive currents with an applied voltage, the resistance and capacitance of fluid test cell can be obtained independently from different t...

Infrared stimulated luminescence (ISL) occurred in CaS:Eu,Sm due to formation of luminescent centres Eu 2+ and electron trapping centres Sm 3+. The electron trapping centres Sm 3+ became occupied (forming Sm 2+ by trapping excited electrons) in photoluminescence (PL) excitation (PLX) process causing simultaneous ionization of luminescent centres Eu...

The photoluminescence emission (PLE) mapping and infrared-stimulated luminescence (ISL) spectra of CaS:Eu,Sm demonstrated that Eu is formed in Eu 2+ as a luminescent centre, whereas Sm is formed in Sm 3+ as an electron-trapping centre by replacing Ca 2+ in the CaS host lattice. It was found that electron trapping occurred in the photoluminescence e...

CaS : Eu,Sm thin films were deposited using the rf magnetron sputtering technique. XRD studies demonstrated a great improvement in the crystalline structures of CaS : Eu,Sm thin films after post-thermal annealing, which also led to an increase in the refractive index of CaS : Eu,Sm thin films. The photoluminescence (PL) and infrared-stimulated lumi...

The luminescence of CaS doped with Eu2+ was studied under hydrostatic pressure at room temperature. Besides the main Eu2+ emission peak, a low-energy peak emerges with increasing pressure. The results are explained in terms of a single configuration coordination model. © 2003 American Institute of Physics.

In order to study different characteristic luminescence of Eu2+ and Sm3+, delayed photoluminescence (DPL) and infrared stimulated luminescence (ISL) spectra of CaS doped with europium and samarium have been investigated. The influence of Eu and Sm concentration on luminescence of Eu2+ in photoluminescence (PL) and ISL was respectively studied. It w...

Films of the potential electron trapping optical memory medium CaS: Eu, Sm produced from optimally composed sputtering targets, are themselves optimized by postdeposition thermal processing in a sulfur atmosphere. X-ray diffraction studies and a variety of spectroscopic techniques are used to study the development of crystalline structure and the d...

In this paper, delayed photoluminescence (DPL) and infrared-stimulated luminescence (ISL) spectra of Eu2+ and Sm3+ in CaS : Eu, Sm have been investigated. It is found that Eu2+ and Sm3+ show different characteristic luminescence in DPL. The explanation is based on the fact that Eu2+ ideally have the same local environment in the lattice position wh...

The preparation of CaS films by magnetron sputtering with the requisite properties for optical recording is studied. Sputtering targets are produced from pressed powders permitting rapid investigation of the optimum dopant concentration of the rare earth ions Eu and Sm. The problem of negative ion re-sputtering is addressed but low sputtering rates...