Applications of laser spectroscopy to analytical chemistry, environmental monitoring and medicine

Abstract: In this thesis spectroscopic techniques have been used in the fields of analytical chemistry, environmental and medical applications. In analytical chemistry, laser induced fluorescence was used to image the separation of substances during capillary electrophoresis. Here, an optical fibre imaging technique facilitated a higher sensitivity compared with a lens imaging technique. The motion of the substances was also monitored. In a similar experiment, laser induced fluorescence was used to image substances that do not exhibit fluorescence. Levitated drops have also been used as a wall-free cuvette during the study of fat-cell behaviour and protein precipitation, where laser induced fluorescence detection was used in the first part and light scattering detection in the second part. For environmental monitoring a lidar (light detection and ranging) system was used. Here, measurements have been performed at different monumental buildings to detect both biodeteriogen invasion and protective treatment. The system was also moved onto a ship for experiments in the Mediterranean Sea. Laser induced fluorescence was here used for monitoring of chlorophyll contents in the seawater together with distributed organic matter (DOM). With the use of depth resolved measurements, the water absorption was studied. In medical applications, laser induced fluorescence techniques have been used for spectral imaging of human normal and tumour tissue. For the treatment of the tumours, photodynamic therapy was employed. Three to six optical fibres, connected to a diode laser, were used and inserted in the tumour tissue. A sensitising agent was utilised to demarcate tumour tissue by fluorescence, and also to induce cell death.