Lasers induced circular dichroism

Sensitive Optical Detectors. More sensitive optical techniques that have been used with CE include fluorescence, refractive index, chemiluminescence, Raman spectrophotometry, and circular dichroism. The most sensitive optical detection method used in CE is laser-induced fluorescence (LIE), which is capable of detection limits in the 10 to 10" mol (or better) range. This detection mode is easily accomplished with analytes that are either easily labeled with a fluorescent substrate (e.g., intercalators for double-stranded DNA) or are naturally fluorescent (e.g., proteins or peptides containing tryptophan). CE systems have also been interfaced with mass spectrometers, and electrochemical detection methods have been developed, although such detectors must be isolated electrically from the electrophoretic voltages. 

Laser-Induced Circular Dichroism Resonance Enhancement... 

Mollenauer and co-workers used the MCD effect in the absorption band of an F center in order to detect, for the first time, changes in the ground state spin polarization induced by ENDOR in the relaxed excited state. A He-Ne laser served for optical pumping as well as for monitoring the magnetic circular dichroism, while several preceding experiments still had used conventional lamps. The laser beam, which passed a quarter wave plate with a stress modulation frequency of SO kHz, was irradiated onto a KI crystal that contained the F centers under study. The transmitted laser light was monitored with a photomultiplier and processed with lock-in technique. 

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