Structural Analysis of Carbohydrate Polymers by Using Infrared Free Electron Laser

Application of intense infrared (IR) laser to analyze carbohydrate polymers is shown. IR free electron laser (FEL) driven by a linear accelerator possesses unique spectroscopic features in terms of extensive wavelength tunability and high laser energy in the IR region from 1000 cm-1 (10 mm) to 4000 cm-1 (2.5 mm). The FEL can induce IR multiphoton dissociation reaction against various molecules by giving the vibrational excitation energy to the corresponding chemical bonds. Chitin from crayfish and cellulose fiber were irradiated by the FELs that are tuned to nC-O (9.1-9.8 mm), nC-H (3.5 mm), and dH-C-O (7.2 mm) in glycoside bonds, and their low-molecular weight sugars were separated, which were revealed by combining synchrotron-radiation IR spectroscopy and electrospray ionization mass spectrometry. The intense IR laser can be proposed as “molecular scalpel” for dissecting and direct analyzing internal components in rigid biopolymers.