Comparison of the second-harmonic response from Ag(111) in UHV and solution

A Comparative Second Harmonic Study of Cu(111) in UHV and in Solution

“…where aOO ) and c ( 3 ) are referred to as the isotropic and anisotropic coefficients, The vacuum experiments were performed in a chamber with a base pressure of 3.5 x 10 -10 torr and the crystal was cleaned by sputtering and annealing procedures.…”

“…The difference in angle of incidence for the two experiments cannot account for this observation. Since at the PZC the effect of the DC electric field should be minimal, these differences in the SH response can not be attributed to the presence of the static field which could cause an additional nonresonant X ( 3 ) contribution [10], or to a significant potential induced shift in surface electronic states or bands causing resonance effects [2]. these changes can produce a surface response which is the same as that measured for clean Cu(Ill) in UHV [13].…”

“…respectively.For metals, both coefficients are complex and are comprised of susceptibility tensor elements and corresponding fresnel factors at w and 2 w. The tensor elements incorporated into the coefficient a(00) represent the out-of-plane response (perpendicular to the surface) whereas c( 3 ) contains the surface tensor element responsible for the in-plane polarization. By fitting the data to equation(2), one can 3 verify the symmetry and obtain the ratio c( 3 )/a(o).…”

Hydrodynamic model for sum and difference frequency generation at metal surfaces

“…This is the only component that is affected by the spatial dispersion of the metal 23,25 within the jellium model. As this model cannot explain the azimuthal anisotropy of the SHG signal, [26][27][28][29][30] several attempts have been made to incorporate crystallinity effects. [31][32][33][34][35][36] It has been shown that different components of the surface [33][34][35][36] response are characterized by different length scales whose relation to surface sensitivity is nontrivial, i.e., sensitivity not always decreases with increasing length scale.…”

Surface Second Harmonic Generation Studies of Stepped Ag(111) Electrode Surfaces

“…Previous comparative measurements of Ag(l 11) in an electrochemical environment and in UHV have shown that when the Ag(1 11) surface is biased at the potential of zero charge (PZC), the SH response in solution under both resonant and nonresonant conditions is nearly identical in magnitude and phase angle with the response in UHV. 15 In these solution studies the applied dc field is used to elucidate the role of the steps in the SH response. The studies are perfonned under nonresonant conditions1 6 to avoid altertions of the electronic structure which can result from the increased step density.…”