Fluorescence spectrofluorimeter, model LS-55 (PerkinElmer), designed for steady-state fluorescence, phosphorescence, bioluminescence and chemiluminescence measurements. Spectral range covered: ~200 nm – 900 nm (UV–Visible). The system uses a pulsed Xenon lamp as an excitation source, ensuring high stability and reduced photodegradation of samples. Spectral separation is achieved by excitation and emission monochromators, equipped with variable slits and holographic gratings, to reduce stray light and increase the sensitivity and reproducibility of measurements. The spectral resolution is adjustable by adjusting the slits, with a minimum step of 0.1 nm, depending on the experimental conditions. The instrument allows the acquisition of excitation and emission spectra, synchronous scans, 3D excitation–emission scans, kinetic measurements, as well as polarization and anisotropy determinations. The system is compatible with a wide range of accessories for liquid and solid samples, microplate reader and temperature controlled measurements. Instrument control and data acquisition are performed by dedicated FL WinLab software, which allows automated operation, quantitative analysis and validation of instrument performance.