(a) Schematic representation of the experimental setup employed; W: glass wedge, M: mirror, B: bandpass filter with a width of at , MO: microscope objective, S: sample, N: notch filter; and SPAD: single-photon counting avalanche photodiode. Dashed line: external reference beam. (b) Energy flow (Poynting vector ) towards a dipole in resonance and (c) out of resonance ( linewidth). Scale bars in (b) and (c) correspond to one wavelength. (d) Weak reflection from the sample as reference signal.
(a) Simultaneously recorded fluorescence (lower trace, right axis) and absorption spectrum (upper trace, left axis). No external reference beam was used. The solid lines are fits to the data. Prior to fitting the absorption signal a slow cosine modulation with a period far longer than the range of the frequency scan was subtracted; this signal was interpreted as experimental artifact, probably related to interferences on optical elements of the setup. The light gray box indicates the limits of the shot noise. The integration time was /point. (b) Zoom on a regime of (a) displaying the response of a molecule that is blinking while being scanned. (c) Correlation between the amplitude of the absorption signal and the half-width at half maximum linewidth of single-molecule resonance. The data points are taken from the spectrum in (a).
Two consecutive sets of simultaneously recorded fluorescence (lower traces, right axis) and absorption spectra (upper traces, left axis), with external reference beam. For details see text. The gray boxes indicate the limits of the shot noise in the absorption signal. Offsets were added for clarity. The thicker black lines are fits to the data. The integration time was /point.
Simultaneously recorded time trace of a single molecule in absorption (upper trace, left axis) and in fluorescence (lower trace, right axis). The molecule fluoresces with some fluctuations and a decreasing signal due to piezodrift of the sample scanner, until it jumps away after about . The beginning of the traces was exponentially fitted with the same coefficients in both traces. The horizontal lines after the spectral jump are averages of the remaining trace. The integration time was /point. The inset shows the normalized cross correlation of absorption and fluorescence time traces truncated at .
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