A dual-beam thermal lens optical fiber spectrometer was developed and tested with aqueous solutions of the rare-earth ion Nd3+. An argon ion pumped dye laser beam was delivered to a sample cuvette through optical fibers of 100, 200, and 400 {\textmu}m core diameter. The thermal lens signal was detected with a He-Ne laser guided to a photodiode detector by an optical fiber of 200 {\textmu}m core diameter. Theoretical values for the optical aperture, excitation and probe beam radii, and distances from the sample to the probe beam waist and to the aperture-detector were calculated and compared to experimental results. Theoretical thermal lens enhancement factors that take into account the radius of the excitation beam show good agreement with the experimental values. A detection limit of 7 x 10-8 M and an enhancement factor of 0.9 were obtained for an Incident power of 25 mW and a power density of 31 W cm-2.
}, year = {1991}, booktitle = {Analytical Chemistry}, journal = {Analytical Chemistry}, series = {Analytical Chemistry}, volume = {63}, pages = {1927-1932}, month = {09/1991}, doi = {10.1021/ac00018a007}, note = {LBNL-31077 NOT IN FILE
}, language = {eng}, }