The enhancement of optical processes near rough surface of metals

Abstract

Last decades the enhancement of optical transitions near metal surface was observed under study the optical processes (luminescence, Raman scattering, IR absorption). The effect consists in an essential increase of the intensity of transition (for example, an effective cross-section increases by factor 10 5 …10 11 for Raman scattering and 10…10 4 for IR absorption) or efficiency of the processes near metal surface (e.g. generation of second harmonic). We have analyzed a various experimental techniques that made it possible to achieve an enhancement in surface enhanced infrared absorption (SEIRA), surface enhanced Raman scattering (SERS), metal-enhanced fluorescence. Under the conditions of our experiment and according to literature data, there was observed enhancement factor which equal to 3…20 for vibrations of various molecular groups in SEIRA. Peculiarity of another optical amplifier, namely, colloidal gold nanoparticles, which were effectively used for enhancement of signal in IR absorption and Raman scattering, metal-enhanced fluorescence, has been studied also. Different roughness of gold surface leads to changes in an enhancement factor. The structural features of bovine serum albumine (BSA)-colloidal gold system and enhancement of guanine that obtained in SEIRA experiment are discussed. Atom force microscopy (AFM) technique was applied to test the roughness of the metal surface. We made an attempt to model the factor of enhancement of electrical field and its frequency dependence for different metal surfaces, and ascertained that silver, gold and copper are the best.

Study of Membrane Protein Monolayers Using Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS): Critical Dependence of Nanostructured Gold Surface Morphology

“…Here, we show that the immobilization process itself strongly modifies the surface features. Since the enhancement mechanism is based on the electric field rise near the curved metal surface, the modification of the three-dimensional (3D) structure is critical. A reorganization on the surface takes place and the size of the nanostructures changed after adding the protein.…”

Nucleic Acid Interaction and Interfaces with Single-Walled Carbon Nanotubes

“…). Earlier we studied the validity of the use of the effect of enhancement of infrared absorption by metal surface for nucleic acids, lipids, amino acids and albumin (Dovbeshko et al, 2002;Dovbeshko et al, 2004; Dovbeshko et al, 2006 (b)) deposited onto Au substrate in the reflectance experiments. The results show that when using the SEIRA method for the study of IR absorption of nucleic acids (and for other molecules), no deformation of contour of the absorbance bands is observed as compared with the spectrum on neutral CaF 2 .…”

Tuning the photoluminescence of CdTe quantum dots by controllable coupling to plasmonic Au nanoparticles

“…One of their major advantages over bulk semiconductor counterparts and organic semiconductors and chromophores is the tunable narrow-band photoluminescence (PL) and optical absorption spectra which can cover the whole optical range from UV to NIR [4]. A controllable increase or decrease of the QD PL intensity via their coupling to plasmonic nanoparticles (NPs) is the basis for many potential optoelectronic and sensing applications [5,6,[15][16][17][7][8][9][10][11][12][13][14]. The underlying mechanism is an interplay of the absorption and PL enhancement by a strong electric field of the localized surface plasmon resonance (LSPR) of noble metal NPs and PL decrease due to non-radiative charge and energy transfer between the QD and NP.…”

“…The underlying mechanism is an interplay of the absorption and PL enhancement by a strong electric field of the localized surface plasmon resonance (LSPR) of noble metal NPs and PL decrease due to non-radiative charge and energy transfer between the QD and NP. The applications of these effects can lead to improved performance of light emitters [11,15,17,18], enhancement of the QD absorption in solar cells [5], and temperature or pressure sensors [10,19,20].…”