Setup / Configuration

Literature

• Time resolved (non )resonant Raman and transient absorption of excited states
• Time resolution:100 fs (fwhm)
• Maximum time scan: 500 ps
• Excitation and detection range: 520 nm 750 nm/260 nm 375 nm; 800 nm and 400 nm

• R. R. Frontiera, R. A. Mathies, Laser & Photonics Reviews 2011, 5, 102-113.

The image shows the sample position (in figure the sample is replaced by an alignment pin hole) and the pathways of the actinic (blue), Raman (green) and probe (red) pulse paths (yellow figures are a guide for the eye to show the beam geometry). To compensate for shot to shot laser fluctuations, a replica of the probe pulse is detected as a reference shot per shot (dashed lines). Probe and reference are then dispersed to be detected by a single shot broadband double detector. Inset shows a zoom of the sample position.

The stimulated Raman signal is generated by stimulating the Raman emission process, induced by a ps pulse (Raman pump), with a sub 100 fs broadband pulse (probe pulse), as depicted in the figure below.

When the sample is pre-excited with a pump pulse (actinic pulse) the Raman spectrum of the excited state can be detected.

The peculiarity of or set-up is that we have a double array of detectors (512 pixels each) to monitor simultaneously the probe spectrum alone and with the Raman pulse (see figure on the left), after the interaction with the pumped or unpumped sample. This allows us to compensate for shot to shot laser fluctuations and to measure at once also the transient absorption.