TR-OS (Diff)

This setup for Time-Resolved Optical Spectroscopy (TR-OS) offers the possibility to measure simultaneously the broadband time-resolved optical properties (reflectivity or transmittivity) along two orthogonal directions. After carefully aligning the crystal axes of the sample under scrutiny along these directions, the setup allows one to sample simultaneously the ΔR/R or ΔT/T along two crystalline directions. This is particularly relevant for all the materials with an anisotropic crystal structure, for systems displaying anisotropies in the electronic properties or for photoinduced anisotropies.

The probe spectral range covers the interval 400-1000 nm (corresponding to 1.2-3.1 eV). The pump is at 800 nm (1.55 eV) or at 400 nm (3.1 eV).

It is possible to mount the samples in a cryostat or in a heating chamber, which allows to perform measurements in the temperature range from 10 K to 470 K.

Figure: ΔR/R measurements of the quasi-1D CDW material (TaSe₄)₂I along the c-axis (direction ∥ to the CDW) and along one of the a-axes (direction ⊥ to the CDW), as a function of sample temperature (above or below T_c=263 K). Cuts at fixed time after excitation or at fixed photon energy deliver information on the non-equilibrium spectral changes or the relaxation dynamics after photoexcitation, respectively.