Raman Investigation on Silicon Nitride Chips after Soldering onto Copper Substrates.

The unique electrical properties of silicon nitride have increased the applications in microelectronics, especially in the manufacture of integrated circuits. Silicon nitride is mainly used as a passivation barrier against water and sodium ion diffusion and as an electrical insulator between polysilicon layers in capacitors. The interface with different materials, like semiconductors and metals, through soldering may induce residual strains in the final assembly.

Micro-Raman for Local Strain Evaluation of GaN LEDs and Si Chips Assembled on Cu Substrates.

Integrated circuits are created by interfacing different materials, semiconductors, and metals, which are appropriately deposited or grown on substrates and layers soldered together. Therefore, the characteristics of starting materials and process temperatures are of great importance, as they can induce residual strains in the final assembly. Identifying and quantifying strain becomes strategically important in optimizing processes to enhance the performance, duration, and reliability of final devices.

Raman study of the polybenzimidazole-phosphoric acid interactions in membranes for fuel cells.

Poly(2,5-benzimidazole) (AB-PBI) membranes are investigated by studying the FT-Raman signals due to the benzimidazole ring vibration together with the C-C and C-H out-of- and in-plane ring deformations. By immersion in aqueous ortho-phosphoric acid for different time periods, membranes with various doping degrees, i.e.

Effect of high pressure CO2 on the structure of PMMA: a FT-IR study.

Conformational changes in polymer films exposed to high-pressure CO(2) have been investigated with Fourier transform infrared (FT-IR) spectroscopy. The experimental setup, based on a custom-made stainless steel optical cell with CaF(2) windows, allows measurements in a CO(2) environment for pressures up to 6 MPa, in a temperature range from 293 to 353 K and in the mid-infrared (1000-4000 cm(-1)). Poly(methyl methacrylate) (PMMA), a polymer with a side group (C-type), was studied to monitor the spectral changes as a function of CO(2) pressure and was compared to poly(D,L-lactic-co-glycolic acid) (PLGA), a polymer without a side group (B-type).

Broadband electric spectroscopy at high CO2 pressure: dipole moment of CO2 and relaxation phenomena of the CO2-poly(vinyl chloride) system.

Broadband electric spectroscopy (BES) is a technique that shows promise in studying the interactions of dense or supercritical gases with polymers, particularly with respect to chain mobility. Polymers that are treated with dense gases show a reduction in the viscosity, glass transition, and melting temperature. A high pressure cell for BES has been constructed that can be used from ambient temperature and pressure to 353 K and 15 MPa and over a frequency range from 20 Hz to 1 MHz.

First time-resolved EPR observation of Nafion photochemistry.

Time-resolved EPR spectra of UV-irradiated Nafion reveal the formation of spin-polarized excited triplet states and allow the detection of photoinduced triplet-triplet energy transfer processes through hydrogen bonds between water and sulfonic acid groups.

Time-resolved EPR observation of synthetic eumelanin-superoxide radical pairs.

TR-EPR spectra of UV irradiated synthetic eumelanin in equilibrium with air oxygen, reveal the formation of melanin-superoxide radical pairs and allow to determine both the electron dipolar interaction D and the exchange interaction J between the two radicals.

Time-resolved EPR investigation of [70]fulleropyrrolidine nitroxide isomers.

A novel [70]fulleropyrrolidine functionalized with a nitroxide radical has been synthesized. After pulsed photoexcitation, time-resolved electron paramagnetic resonance (EPR) spectra have been recorded in liquid solution at standard X-band (9.5 GHz) and W-band (95 GHz) microwave frequencies.

Investigation of water structure in nafion membranes by infrared spectroscopy and molecular dynamics simulation.

The structure and interactions of water species in hydrated Nafion membranes as a function of water content were investigated on the basis of medium-infrared spectral analysis and molecular dynamics (MD) simulations. The spectral decomposition of the FT-IR data in the stretching OH region was performed on different levels of hydration of the sulfate functional groups (lambdaH2O/RSO3- = 2-22). Quantum mechanical calculations of two model systems [perfluoroethanesulfonic acid/(H2O)6 cluster] and a [perfluorobutanesulfonic acid/(H2O)6 crystal] were carried out in order to account for the band assignments of Nafion in the stretching OH region (2500-4000 cm-1).