Fig. 1.

(A) Absorption spectra of AuNRs of different abstract ratios (ARs): green (AR = 1.2), blue (AR = 2.3), and cyan (AR = 3.8). The unit of the lower axis is given as a frequency shift relative to the 488-nm laser excitation for the convenience of comparison with B. The upper axis provides the corresponding wavelengths. The y axis is the absorbance (abs), i.e., the negative of the base-10 logarithm of the optical transmission. (B) Spectra of water and AuNRs of different absorption peaks excited by 488-nm cw laser with 1-mW power. S is the spectral density of the intensity of scattered light, and P is the average excitation laser power. Thus, the y axis is the output of the CCD camera of the spectrometer normalized by the data acquisition time and the power of the excitation laser.