Optical second harmonic generation, surfaces

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... 

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

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... 

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. 

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. 

Recently, we [13,14] evidenced by ATR-IR spectroscopy that the membrane potential of ionophore-incorporated, PVC-based liquid membranes is governed by permselective transport of primary cations into the ATR-active layer of the membrane surface. More recently, we [14 16] observed optical second harmonic generation (SHG) for ionophore-incorporated PVC-based liquid membranes, and confirmed that the membrane potential is primarily governed by the SHG active, oriented complexed cations at the... 

Optical second harmonic generation (SHG), which is the conversion of two photons of frequency u to a single photon of frequency 2co, is known to be an inherently surface-sensitive technique, because it requires a noncentrosymmetrical medium. At the interface between two centrosymmetrical media, such as the interface between two liquids, only the molecules which participate in the asymmetry of the interface will contribute to the SHG [18]. SHG has been used as an in-situ probe of chemisorption, molecular orientation, and... 

Optical second harmonic generation from electrode surfaces is employed in situ to study the... 

All spectroscopic evidence on the composition of a relatively thin layer at the membrane surface was thus found to be in agreement with the interpretation of permselectivity as being due to the exclusion of counteranions from the membrane phase. However, the depth accessible to ATR-IR is of the order of 0.1 1.0 pm and is thus too large for the observation of phenomena in the region in closest proximity to the membrane/aqueous interface in which charge separation is assumed to take place. Optical second harmonic generation (SHG), which has an even more pronounced surface sensitivity than ATR-IR, was recently shown to be very suitable for the investigation of the interface between ISE membranes and sample solutions."" ... 

Refs. [i] Hoke R (2008) Surface and interface analysis an electrochemists toolbox. Springer, Berlin [ii] Tadjeddine A, Peremans A (1998) Non-linear optical spectroscopy of the electrochemical interface. In Clark RJH, Hester RE (eds) Advances in spectroscopy (spectroscopy for surface science), vol. 26. Wiley, Chichester, p 159 [iii] Shen YR (1990) In Gutierrez C, Melendres C (eds) Spectroscopic and diffraction techniques in interfacial electrochemistry (NATO ASI series C, vol. 320). Kluwer, Dordrecht, p 281 [iv] Shen YR (1986) Applications of optical second-harmonic generation to surface science. In Hall RB, Ellis AB (eds) Chemistry and structure at interfaces. VCH, Deerfield Beach, p 151 [v] Williams CT, Beattie DA (2002) SurfSci 500 545... 

Refs. [i] Richmond GL, Robinson JM, Shannon VL (1988) Progr Surf Sci 28 1 [ii] Richmond GL (1991) Optical second harmonic generation as an in situ probe of electrochemical interfaces. In Bard A] (ed) Electroanalytical chemistry, vol. 17. Marcel Dekker, New York, p 87 [iii] Corn RM, Romagnoli M, Levenson MD, PhilpottMR (1984) / Chem Phys 81 4127 [iv] Georgiadis R, Richmond GL (1991) / Phys Chem 95 2895 [v] Holze R (2008) Surface and interface analysis an electrochemists toolbox. Springer, Berlin... 

Stack, A.G., Higgins, S.R., and Eggleston, C.M., Point of zero charge of a corundum-water interface probed with optical second harmonic generation (SHG) and atomic force microscopy (AFM). New approaches to oxide surface charge, Geochim. Cosmochim. Acta, 65, 3055, 2001. 

Fitts, J.P. et al.. Electrostatic surface charge at aqueous/a-AljOj single crystal interfaces as probed by optical second-harmonic generation, J. Phys. Chem. 11.. 109, 7981, 2005. 

Y. R. Shen, "Studies of Liquid Crystal Monolayers and Films by Optical Second Harmonic Generation," Liquid Crystals, Vol. 5, p. 635 (1989) see also Y. R. Shen, "Surface Properties Probed by Second-Harmonic and Sum-Frequency Generation," Nature, Vol. 32Zi No. 6207, p. 519 (1989). 

Optical second-harmonic generation experiments give a more detailed description of the anchoring at a microscopic scale [68,69 see also Chapter 5]. The molecule/surface interaction determines the orientational distribution in a thin surface layer extending up to 1 nm. The bulk uniaxial order develops on top of this layer via a transition layer of thickness which is well described by the usual mean-field theory, possibly including non-uniaxial components of the tensor order parameter. 

Brewster angle ellipsometry (BAE) and surface optical second harmonic generation (SHG, see Chap. 5) were used to study the growth of 8CB films, evaporated in air onto glass (BK7) substrates, covered with a 15 nm thick film of poly(vinyl cinnamate) (PVCN) [48]. As the thickness of 8CB on PVCN layers was far below the optical wavelengths, the Drude formula for the ellipsometric coefficient at the Brewster angle, ps, (4.3), was used. The ellipticity coefficient of the 8CB adsorbate was calculated as... 

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