Figure 2
One-photon upconversion of the chlorophylls in the absence of a silver film excited by a continuous wave laser at the wavelength 735 nm.
(a) Temperature-dependent upconverted fluorescence spectra of the chlorophylls suspensions. (b) The logarithmic fluorescence intensity ln(IFL) as a function of −1/kT. The slope, ω0 = ∂lnIFL/∂(−1/kT), corresponds to the averaged phonon energy captured in the anti-Stokes upconversion process of the chlorophylls. (c) The excitation power dependence of the upconversion fluorescence intensities of the Chl-mix, pure Chl-a and RDM-b. The power index, ν = ∂lnIFL/∂lnpexc, indicates the number of photons involved in the anti-Stokes upconversion processes.
