Fig. 1.

Normal Raman spectrum (black) and SERS spectrum (dashed) of pure turnip yellow mosaic virus (TYMV). SERS spectra of the extracts (1 μl) from healthy (blue) and TYMV-infected (red) leaves. The shades with the same color indicate the corresponding standard deviation (1σ). The spectra of samples were collected with an exposure time of 40 seconds (excitation wavelength: 785 nm). The laser power at the sample was approximately 45 mW.