Infrared absorption enhancement phenomenon on nano materials

2^nd International Conference and Exhibition on Materials Science & Engineering

October 07-09, 2013 Hampton Inn Tropicana, Las Vegas, NV, USA

Jae Hong Park, Jun Yong Park, Seok Woo Jeon, Woo Choong Kim, Moon Seop Hyun, Chi Won Ahn and Hee Yeoun Kim

Accepted Abstracts: J Material Sci

Abstract :

The intensification of infrared-active vibrational modes of molecules in close proximity to nanometer-thick metal films, commonly known as surface-enhanced infrared absorption (SEIRA), is receiving increased attention from both a phenomenological and practical viewpoint. The resonant excitation of plasmon in metallic nanostructures can provide large field enhancements on the surfaces of metals, which in turn provide dramatic increases in the detected spectroscopic signals for molecules adsorbed on their surfaces. The most widely used surface enhanced spectroscopy (SES) is surface enhanced Raman scattering (SERS), where the electromagnetic enhancement factor is proportional to the fourth power of the field incident on the molecule. Recently there has been a resurgence of interest in another type of SES, surface enhanced infrared absorption. It has been widely applied to surface trace analysis, bio-sensing, electro sorption, and electro catalysis because of its significant amplification of surface signal and simple surface selection rule. The surface enhanced infrared absorption can be observed easily on metal island films prepared by vacuum evaporation or sputtering and electrochemical or electroless deposition. Metal colloids also support the enhancement. Like surface-enhanced Raman scattering (SERS), SEIRA is chiefly of electromagnetic origin, that is, due to an increase in the local optical field exciting the adjacent molecule. Metal nano clusters much smaller than the wavelength of light facilitate the interaction of the infrared radiation with the metal and adsorbed molecules, resulting in the enhancement. It was explained that the enhancement is greatly affected by the size, and planer density of metal nano clusters compared with metal nano films. Phenomenological and theoretical difference of infrared absorption in broad ranges of wave length including near field to far field infrared rays between metal nano clusters and metal nano films. Especially, metal nano clusters exhibit much higher infrared absorption than metal nano films on broad ranges of wave length. The phenomenon of infrared absorption in the range of near infrared wave length was different from that of far infrared wave length. This different phenomenon involves shift of resonant peaks and absorption intensities on them. Also the planar density of the metal nano clusters suggests a mechanism to explain the phenomenon.

Biography :

Jae Hong Park has completed his Ph.D. at the age of 33 years from Seoul National University and postdoctoral studies from Korea Institute of Science and Technology and Harvard Medical School, respectively. He is a senior researcher of National NanoFab Center in Korea. He has published more than 30 papers in reputed SCI journals and serving as an editorial board member of repute.