[1] M. Fleischmann, P. J. Hendra, and A. J. McQuillan, Chem. Phys. Lett. 26, 163 (1974).

[2] J. A. Creighton, Surf. Sci. 124, 209 (1983).

[3] N. R. Isola, D. L. Stokes, and T. Vo-Dinh, Anal. Chem. 70, 1352 (1998).

[4] W. Ke, D. Zhou, J. Wu, and K. Ji, Appl. Spectrosc. 59, 418 (2005).

[5] K. Kneipp, H. Kneipp, S. Abdali, R. W. Berge, and H. Bohr, Spectroscopy 18, 433 (2004).

[6] X. Zhang, N. C. Shah, R. P. Van Duyne, Vibrational Spectroscopy 42, 2 (2006).

[7] R. Z. Tan, A. Agarwal, N. Balasubramanian, D. L. Kwong, Y. Jiang, E. Widjaja, and M. Garland, Sensors and Actuators A 139, 36 (2007).

[8] J. Guo, W. Cai, J. Yang, and Z. Sun, Chin. Opt. Lett. 6, 421 (2008).

[9] J. Zhu, Y. Zhang, L. Wu, Z. Wang, and Z. Sun, Chin. Opt. Lett. 6, 526 (2008).

[10] X. Huang, P. K. Jain, I. H. EI-Sayed, and M. A. EISayed, Nanomedicine 2, 681 (2007).

[11] P. C. Lee and D. Meisel, J. Phys. Chem. 86, 3391 (1982).

[12] Y. Li, R. Chen, H. Zeng, Z. Huang, S. Feng, and S. Xie, Chin. Opt. Lett. 5, 105 (2007).

[13] S. S′anch′ez-Cort′es, J. V. Garc′ a-Ramos, G. Morcillo, and A. Tinti, J. Colloid Interf. Sci. 175, 358 (1995).

[14] K. J. Jalkanen, J. Phys: Condens. Matter 15, S1823 (2003).

[15] P. J. G. Goulet and R. F. Aroca, Can. J. Chem. 82, 987 (2004).

[16] P. Li, J. Zhang, L. Zhang, and Y. Mo, Vibrational Spectroscopy 49, 2 (2009).