Proper Ways for Detecting Vibration Modes of Water Using a Micro-Raman Setup
Chang-Xhuan Yang1*, Chi-Hung Lee1, Wen-Hsien Li1
1Physics, National Central University, Zhongli, Taiwan
* presenting author:YANG chang-xhuan,
Several reports have suggested that illuminations of light onto Au nanoparticles (NPs) placed in water can initiate surface plasma resonance (SPR) that are capable of weakening the molecular interactions in water, frequently detected using a micro-Raman setup. Here, we demonstrate that Raman spectrum of water can be largely affected by the excitation laser beam, which can lead to unphysical results suggested in the Raman spectrum. The Au NPs were fabricated by employing the gas-condensation method, deposited on glass subtracts. Binding between Au NPs and glass are strengthen by anneal the complex at 500oC for 2 mins. X-ray diffraction profile is used to determine the size distribution and mean size for the Au NPs deposited on the glass subtracts. Absorption spectra obtained in the transmission geometry indicate blue shift of the absorption bands for the Au NPs, as expected. Two Au-glass complexes of this type are stick together face-to-face but separated by 1 mm to form micro-channel for water to slowly flow through. Raman spectra of water were taken before and after directing the DI water to flow slowly, at a controlled flow rate, through the micro-channel under illumination of green light from an LED. In identify the effects on micro-Raman spectra from excitation laser beam, excitation laser at various powers were employed. Results from the currently asserting SPR effect and from excitation laser itself will be presented.

Keywords: Nanoparticle, Surface plasma wave, hydrogen bond