Equipment for transient absorption and fluorescence decay study

The equipment for transient absorption detection and fluorescence decay study of solid samples has the following main parameters.

Spectral range 240 – 1100 nm is covered (gratings 1200, 600 and 300 lines/mm)
Temperature range 90 – 450 K, (liquid nitrogen cryostat)
Temperature range 300 – 700 K, (sample heater)

Excitation by pulsed electron beam:
energy of electrons 270 KeV
pulse length 8 ns
excitation density 1012 el/cm2 per pulse

Time resolution of registration 1.5 ns

The modified pulsed electron beam source generating 50 ps pulses as well as corresponding   improvement of registration channel are foreseen

The transient absorption can be determined for transparent solids, sample size approximately 10x8x3 mm, three surfaces of the sample must be optically grade. The sizes of samples for fluorescence study could be other and there is not need for transparency. The sample during experiment is in vacuum.

The interaction of light as well as ionizing radiation with material can result in creation of excited states of impurities, dopands and host material defects and excitons. Besides these excitations recharging of defects can be involved as well as creation of new defects. The decay of number of excitations is radiative and can be detected using luminescent methods; however the number nonradiative decay of excitations can be detected by light absorption. More over – some intermediate products of photolysis and radiolysis are short lived and do not directly contribute in luminescence. Thus, in this case, the transient absorption is a method for short lived products detection.