The instrument is designed to explore a fluorescence decay of dim samples. Since the typical time scale of the fluorescence phenomenon spans over the range of 10^-8 s, a much faster setup is required to observe such a quick process. The examined sample is excited with the Picosecond Laser pulse. After deexcitation, the system measures the time of flight of a single photon emitted by the sample. Photon flies through the Monochromator and reaches the Photomultiplier. The statistics of the times of flight evaluated for each photon captured, reconstructs the shape of the fluorescence pulse induced in the sample.
A crucial requirement for a proper FPC-TDC Spectrofluorometer performance is a low probability (<10% per pulse) that the photon reaches the detector. Thus, the instrument is peerless in investigating materials with a low fluorescence yield. System is adapted to examine electrochemical samples.
Quantities measured by the instrument:
- Fluorescence time decay in relation to wavelength of light and polarization potential (in case of electro-chemical sample),
- Emissive fluorescence spectrum,
- I-V characteristics,
- Open Circuit Potential (OCP),
- Current flowing through the sample.
The system consists of:
- Sample Chamber,
- Picosecond Laser,
- Monochromator for UV, VIS and IR range,
- Photomultiplier,
- Potentiostat,
- Electrochemical Cuvette with platinum electrode and reference Ag/AgCl electrode,
- Time to Digital Converter.
Sample Chamber Interior
Optical path of laser beam and fluorescence light from the sample
Picosecond Laser
- Wavelengths: 405 nm, 450-460 nm, 630-640 nm,
- Half width of the pulse duration: 150 ÷ 200 ps,
- Maximum pulse repetition frequency: 1MHz,
- Light power of a pulse: 60 mW,
- Trigger type: TTL up to 1 MHz,
- Power supply: 12 VDC,
Monochromator
- Spectral range: 200 ÷ 1200 nm,
- Motorized slits, controlled via software,
- Entrance and output slit opening range: 0 ÷ 5 mm,
- Motorized internal shutter that provides full cut off of the light beam, controlled via software,
Photomultiplier
R4998 Hammamatsu
- Anode to Cathode voltage range: up to 2500 V,
- Spectral range: 300 ÷ 650 nm,
- Transit time spread (FWHM): 160 ps,
- Rise time: 0.7 ns.
Time to Digital Converter
- Time resolution: 27 ps,
- Maximum Measurement time: 500 ns,
- Additional Reference channel for laser jitter minimalization,
- Maximum impulse rate:
– 500 kHz for 2 channels measurement: sample and reference,
– 1 MHz for 1 channel measurement, - Internal trigger frequency: 1 kHz ÷ 1 MHz),
- External trigger mode, TTL input,
Potentiostat
- Bias potential range: -5 V ÷ 5 V,
- Current ranges: 10 nA, 100 nA, 1 µA, 10 µA, 100 µA, 1 mA, 10 mA,
- Current resolution: from 1 pA to 100 nA (range dependent),
Controller
- Connection with PC: via USB 2.0,
- RS485 socket to control devices,
