Radio-frequency Stark effect modulation of single-molecule lines

Stark effect modulation experiments were performed on single-molecule lines of terrylene in crystalline matrices of n-hexadecane and naphthalene at lo w temperatures. Modulation frequencies in the MHz range were used. The resu lting fluorescence excitation spectra are distinctly different, depending o n the relationship between the modulation frequency omega(m) and the molecu lar line width Gamma. For omega(m) much less than Gamma, the single-molecul e line exhibits a smooth broadening and apparent splitting into two compone nts, whereas for omega(m) much greater than Gamma it develops equidistant s idebands as in the case of phase modulation of an electromagnetic wave. It is further demonstrated that Stark effect modulation in the radio-frequency regime can be used to record absorption signals of single molecules with g ood signal-to-noise ratio. (C) 2000 Elsevier Science B.V. All rights reserv ed.