SEMICONDUCTOR-LASER SPECTROMETRY

A semiconductor laser is more compact and less expensive than a conventional laser. Therefore, scientists prefer to use this light source in analytical spectroscopy. However, the emitting wavelength of the semiconductor laser is located in the near-infrared or deep-red region. Only a limited number of compounds are fluorescent in these spectral regions; we have already developed many analytical reagents and procedures for application. Inorganic species such as potassium ions and oxygen gas, organic molecules such as dyes and surfactants, and biological molecules such as metabolites, enzymes, proteins, and deoxyribonucleic acid have been determined by this method. For example, amino acids are determined at zeptomole levels after labeling them with a dye fluorescent in the deep-red region and separation by capillary electrophoresis. Thus semiconductor laser spectrometry is advantageous for practical trace analysis.