Surface second harmonic generation

One line in bioelectrochemistry is rooted in electrochemical techniques, spectroscopy, and other physical chemical techniques. Linear and cyclic voltammetry are central.Other electrochemical techniques include impedance and electroreflectance spectroscopy," ultramicro-electrodes, and chronoamperometry. To this come spectroscopic techniques such as infiared, surface enhanced Raman and resonance Raman,second harmonic generation, surface Plasmon, and X-ray photoelectron spectroscopy. A second line has been to combine state-of-the-art physical electrochemistry with corresponding state-of-the-art microbiology and chemical S5mthesis. The former relates to the use of a wide range of designed mutant proteins, " the latter to chemical synthesis or de novo designed synthetic redox metalloproteins. " " ... 

Surface-extended X-ray absorption fine structure (analysis) spectroscopy Sum frequency generation Second harmonic generation Surface ionization Secondary ion mass spectroscopy Subtractively normalized interfacial Fourier transform infrared spectroscopy Single potential alteration infrared (spectroscopy)... 

Y., and Somorjai, G. (1986). Studies of alkali adsorption on Rh(lll) using optical second-harmonic generation. Surface Science, 172 466 - 476. 

Optical second-harmonic generation (SHG) has recently emerged as a powerful surface probe [95, 96]. Second harmonic generation has long been used to produce frequency doublers from noncentrosymmetric crystals. As a surface probe, SHG can be caused by the break in symmetry at the interface between two centrosymmetric media. A high-powered pulsed laser is focused at an angle of incidence from 30 to 70° onto the sample at a power density of 10 to 10 W/cm. The harmonic is observed in reflection or transmission at twice the incident frequency with a photomultiplier tube. 

SHG Optical second-harmonic generation [95, 96] A high-powered pulsed laser generates frequency-doubled response due to the asymmetry of the interface Adsorption and surface coverage rapid surface changes... 

Corn R M and Higgins D A 1994 Optical second-harmonic generation as a probe of surface-chemistry Chem. Rev. 94 107-25... 

Brevet P F 1997 Surface Second Harmonic Generation (Lausanne Presses Polyteohniques et Universitaires Romandes)... 

Schaich W L 2000 Calculations of second-harmonic generation for a ]ellium metal surface Phys. Rev. B 61 10 478-83... 

Mendoza B S, Gaggiotti A and Del Sole R 1998 Microscopic theory of second harmonic generation at Si(IOO) surfaces Phys. Rev. Lett. 81 3781-4... 

Pan R P, Wei H D and Shen Y R 1989 Optical second-harmonic generation from magnetized surfaces Phys. Rev. B 39 1229-34... 

Petraiii-Maiiow T, Wong T M, Byers J D, Yee H i and Hicks J M 1993 Circuiar dichroism spectroscopy at interfaces—a surface second harmonic-generation study J. Phys. Chem. 97 1383-8... 

Sitzmann E V and Eisenthal K B 1988 Picosecond dynamics of a chemical-reaction at the air-water interface studied by surface second-harmonic generation J. Phys. Chem. 92 4579-80... 

Boyd G T, Shen Y R and Hansch T W 1986 Continuous-wave second-harmonic generation as a surface microprobe Opt. Lett. 11 97-9... 

Zhu X D, Rasing T H and Shen Y R 1988 Surface diffusion of CO on Ni(111) studied by diffraction of optical second-harmonic generation off a monolayer grating Phys. Rev. Lett. 61 2883-5... 

Reif J, Zink J C, Schneider C-M and Kirschner J 1991 Effects of surface magnetism on optical second harmonic generation Phys. Rev. Lett. 67 2878-81... 

Vollmer R 1998 Magnetization-induced second harmonic generation from surfaces and ultrathin films Nonlinear Optics in Metals e6 K H Bennemann (Oxford Clarendon) pp 42-131... 

Wang H, Yan E C Y, Borguet E and Eisenthal K B 1996 Second harmonic generation from the surface of centrosymmetric particles in bulk solution Chem. Phys. Lett. 259 15-20... 

Shi Z, Lipkowski J, Mirwald S and Pettinger B 1996 Electrochemical and second harmonic generation study of bromide adsorption at the Au(111) surface J. Chem. See. Faraday Trans. 92 3737-46... 

Unlike linear optical effects such as absorption, reflection, and scattering, second order non-linear optical effects are inherently specific for surfaces and interfaces. These effects, namely second harmonic generation (SHG) and sum frequency generation (SFG), are dipole-forbidden in the bulk of centrosymmetric media. In the investigation of isotropic phases such as liquids, gases, and amorphous solids, in particular, signals arise exclusively from the surface or interface region, where the symmetry is disrupted. Non-linear optics are applicable in-situ without the need for a vacuum, and the time response is rapid. 

According to the data obtained with SXRS in salt solutions,519 520 at a < 0 the surface of Au(lll) forms a ( 3 x 22) structure as in a vacuum. At a > 0 the reconstruction disappears and the (1 x 1) structure is observed. On the reconstructed Au(l 11) surface there are 4.4% more atoms than on the (1 x 1) structure and on the reconstructed Au( 100) there are 24% more atoms than on the (1 x 1) structure.506,519 This phase transition shifts in the negative direction with the adsorbability of the anion. The adsorption-induced surface reconstruction of Au(l 11) electrodes has been studied in situ by second harmonic generation by Pettinger et al.521... 

Microscopy methods based on nonlinear optical phenomena that provide chemical information are a recent development. Infrared snm-frequency microscopy has been demonstrated for LB films of arachidic acid, allowing for surface-specific imaging of the lateral distribution of a selected vibrational mode, the asymmetric methyl stretch [60]. The method is sensitive to the snrface distribntion of the functional gronp as well as to lateral variations in the gronp environmental and conformation. Second-harmonic generation (SHG) microscopy has also been demonstrated for both spread monolayers and LB films of dye molecules [61,62]. The method images the molecular density and orientation field with optical resolution, and local qnantitative information can be extracted. 

Com, R. M., In situ second harmonic generation studies of molecular orientation at electrode surfaces, in Adsorption of Molecules at Metal Electrodes, J. Lipkowski and P. N. Ross, Eds., VCH, New York, 1992, p. 391. 

Shen, C. K., Heinz, T. H., Ricard, D. and Shen, Y. R. (1983) Surface-enhanced second-harmonic generation and Raman scattering. Rhys. Rev. B, 27, 1965-1979. 

Simon, H. J., Mitchell, D. E. and Watson, J. G. (1974) Optical second-harmonic generation with surface plasmons in silver films. Phys. Rev. Lett., 33, 1531-1534. 

Chang, Y. M., Xu, L. and Tom, H. W. K. (1997) Observation of coherent surface optical phonon oscillations by time-resolved surface second-harmonic generation. Phys. Rev. Lett., 78, 4649-4652. 

Meech, S. R. and Yoshihara, K. (1990) Time-resolved surface second harmonic generation a test of the method and... 

Fuyukui, M., Watanabe, K. and Matsumoto, Y. (2006) Coherent surface phonon dynamics at K-coverd Pt(lll) surface investigated by time-resolved second harmonic generation. Phys. Rev. B, 74, 195412. 

Akemann W, Friedrich KA, Linke U, Stimming U. 1998. The catal)4ic oxidation of carbon monoxide at the platinum/electrolyte interface investigated by optical second harmonic generation (SHG) Comparison of Pt(l 11) and Pt(997) electrode surfaces. Surf Sci 404 571-575. 

Pozniak B, Scherson DA. 2003. Dynamics of a surface phase transition as monitored by in situ second harmonic generation. J Am Chem Soc 125 7488-7489. 

P. F. Brevet. Surface Second Harmonic Generation, Press Polytech. Univ. Romandes, Fausanne, 1997. 

---