Effect of UV laser radiation with different wavelengths on the spectrum of lignin extracted from hard wood materials

The effect of different wavelength UV laser irradiation on DRIFT spectra of lignin extracted from hard wood was investigated. Changes in the spectra of lignin were studied with 308, 248.5, and 193 nm wavelength of UV laser radiation. To monitor the energy dependence, different number of laser impulses reached the sample’s surface. To investigate quantitatively how the absorption does change the band damage index (BDI) is introduced. Fourier deconvolution and fit of mixtures of Gaussians and Lorentzians were used to decompose the difference spectra into two spectra containing the bands changing their intensity to opposite directions, which made us possible to identify the products and the components destroyed. Opening up of the glucopyranose ring is essential starting point of the decomposition process and all further steps are dependent on the energy and intensity of the photons.