Forward/backward anomaly in second-harmonic generation from a monolayer

Summary form only given. Second-harmonic generation (SHG) is a widely applied nonlinear optical technique to investigate interfacial layers, and the theory thereof is well established. The systems that have been studied include monolayers of long chain liquid-crystal molecules physisorbed on fused-quartz substrates. Using SHG it has been shown that the layer exhibits in-plane symmetry and that the average angle between the molecular axis and the surface normal is rather large.