Figure 6(a) shows the morphology of our Au nanorod arrays. Au nanorods were aligned on a template layer (called the “shape control layer”) having an anisotropic surface morphology prepared by OAD.6 The shape control layer of as the template for Au nanorods is prepared by a serial bideposition (SBD) technique. The glass substrate is set obliquely at a deposition angle of about 80 deg. During deposition, the substrate is rotated in-plane by 180 deg with each deposition of 10 nm of . As a result, the surface of the shape control layer prepared by SBD is corrugated anisotropically.6,7 On the anisotropic shape control layer, Au is also evaporated obliquely in vacuum. The amount of deposited Au is only around 10 nm thick on average. The Au sticks only to the top of the columns, owing to shadowing, and forms elongated nanoparticles (nanorods). Excellent SERS properties are observed, as indicated in Fig. 6(b), when the Raman spectra are measured on the Au nanorod arrays immersed in a solution of 4,4’-bipyridine.6 The SERS spectra can be detected down to of solution within a few minutes after the immersion of samples. In our measurement system, the spot size of the laser is around . The thickness of the nanorod array is of the order of 10 nm. Therefore, at , the number of molecules existing inside the SERS active volume is estimated to be fewer than 10 molecules. Thus, our nanorod arrays have a detection sensitivity of nearly a single molecule. The high sensitivity can be attributed to the high number density of nanorods and effective field concentration between in-line aligned nanorods.