Many important problems in biomedical research and analysis result from the lack of selective detection methods of biomolecules of similar size and structure, but different function. For example, the discrimination of isomeric peptides remains a difficult problem. Recent developments in Laser Desorption/Laser Ionization Mass Spectroscopy (LD/LIMS) have shed some light on this area, but more new methodologies to enhance detection selectivity are clearly needed. The research proposed here describes the development of new techniques based on the ionization spectroscopy of amino acids and small peptides. The apparatus (already under construction at the University of Puerto Rico) will employ a standard design instrument for LD/LIMS. The concentration will be on identifying and classifying sharp spectral features which will fingerprint many of the amino acids in the wavelength region from 205-260 nm. Fragmentation patterns of isomeric oligopeptides will also be measured as a function of laser ionization power. The long term goals of this research project are to develop new useful methodologies for characterizing biomolecules, and to create physical models for the interactions of proteins with light in the far ultraviolet. The powerful technique described in this proposal has many uses with respect to the spectroscopy of large molecules. As our collective expertise develops, this methodology will be extended towards other important problems in biomedical research. The research project provides a strong student support component by emphasizing hands-on training in state-of-the-art techniques in the following areas: Optical and laser methods, vacuum technology, computer hardware and software, and mass spectrometry.