Biomolecules electronic absorption spectroscopy

As mentioned above, the development of theoretical tools appropriate for computational spectroscopy studies capable of describing complex molecular systems and still endowed with the accuracy needed to gain full insight into important real-world processes requires a novel vision old paradigms employed for most of the last century and based on clear-cut space-and-time separations are no longer valid. For example, discussing emission/absorption spectroscopy of photoactive biomolecules or the electron spin resonance signal of labeled systems considered as isolated objects is not a realistic option anymore, and the multiscale nature of these observations must be taken into account at a rather sophisticated level in order to simulate/reproduce/ interpret available experimental data. 

Chromoproteins are characterized by an electronic absorption band in the near-UV, visible or near-IR spectral range. These bands may arise from Jt Jt" transitions of prosthetic groups or from charge-transfer transitions of specifically bound transition metal ions. Thus, chromoproteins which may serve as electron transferring proteins, enzymes or photoreceptors, are particularly attractive systems to be studied by RR spectroscopy since an appropriate choice of the excitation wavelength readily leads to a selective enhancement of the Raman bands of the chromo-phoric site. Moreover, these chromophores generally constitute the active sites of these biomolecules so that RR spectroscopic studies are of utmost importance for elucidating structure-function relationships. 

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