Figure 1.

Photograph (left) and schematic (right) of the photothermal setup showing the optical system consisting of the power detector, cuvette with the sample, and 785 nm near-infrared, continuous wave laser. The distance between the power detector to the collimator was 44 mm, while the distance between the cuvette’s center and the collimator was 11 mm. The thermocouple’s tip was placed 10.5 mm above the laser beam.