Inverted microscope (Zeiss, Axiovert100TV) with halogen-lamp illumination. The microscope is equipped with a 3D piezo scanner (Physik Instrumente, P-733.2DD & P-721.CDQ) allowing for nanometric position control of the sample. The microscope is built as a sample-scanning instrument. Fluorescence excitation is achived by a pulsed Ti:Saphire laser (Spectra; Millenia X, 10W, 532nm; Tsunami, 2W, 700-900nm, 76MHz, 70fs). After split into 2 wavelength or polarization channels the signals are detected on 2 photon-counting self-quenched avalanche photodiodes (PerkinElmer, SPCM-AQR-14, noise <100Hz). Photons are counted by a multichannel scaler card (Becker&Hickl, PMS-200) or by a 4-channel time-correlated single-photon counting module (Picoquant, TimeHarp-200). The instrument response function has a width <120ps. The setup is controlled by LabView. Analysis is performed offline using our Matlab suite.
One-photon and two-photon lifetime experiments