Henry Gerung

Anhydrous solution synthesis of germanium nanocrystals from the germanium(II) precursor Ge[N(SiMe3)2]2

A convenient, simple, single-source solution synthesis of Ge nanocrystals via thermal reduction of Ge(II) precursor Ge[N(SiMe3)2]2 in a non-coordinating solvent at 300 degrees C and 1 atm Ar is described.

Two-photon absorption of matrix-free Ge nanocrystals

The authors demonstrate that solution synthesized Ge nanocrystals (NCs) display a highly nonlinear optical absorption. The Ge NCs with an average diameter of 5±2nm are synthesized from germanium(II) bis(trimethylsilyl)amide with hexadecylamine surfactants at 300°C and 1atm in argon atmosphere. The resulting Ge NCs in a powder form are then dispersed on a silica glass substrate. Femtosecond pulses at 820nm wavelength from a mode-locked Ti:sapphire laser are used to measure a two-photon absorption coefficient of the deposited Ge NCs. The calculated coefficient ranges from 1190to1940cm∕GW.

In situ real-time monitoring of profile evolution during plasma etching of mesoporous low-dielectric-constant SiO2

We have employed attenuated total reflection Fourier transforms infrared spectroscopy (ATR-FTIRS) to monitor the profile evolution of patterned mesoporous, low-dielectric-constant SiO2 films in situ and in real time during plasma etching. A stack of patterned photoresist, anti-reflective coating, and mesoporous SiO2 is etched in an inductively coupled plasma reactor, using CHF3 and Ar. During etching, the IR absorbance of Si–O–Si stretching modes near 1080cm−1 decreases, and the rate of decrease in Si–O–Si absorbance translates to the SiO2 removal rate. When corrected for the exponentially decaying evanescent electric field, the removal rate helps monitor the profile evolution and predict the final etch profile. The predicted profiles are in excellent agreement with the cross-sectional images taken by scanning electron microscopy. In a similar approach, we calculate the absolute total number of C–F bonds in the sidewall passivation and observe its formation rate as a function of time. Assuming that the th...

Exploiting interfacial water properties for desalination and purification applications.

A molecular-scale interpretation of interfacial processes is often downplayed in the analysis of traditional water treatment methods. However, such an approach is critical for the development of enhanced performance in traditional desalination and water treatments. Water confined between surfaces, within channels, or in pores is ubiquitous in technology and nature. Its physical and chemical properties in such environments are unpredictably different from bulk water. As a result, advances in water desalination and purification methods may be accomplished through an improved analysis of water behavior in these challenging environments using state-of-the-art microscopy, spectroscopy, experimental, and computational methods.