Abstract
Carotenoids transfer the light energy to chlorophylls in plants by the use of singlet excited states. Vibration spectroscopy of deuterium-substituted substances can be a powerful tool to investigate the excitation and relaxation processes. β-carotene in natural abundance and 6 different types of deuterium-substituted β-carotene (12-d, 12,12'-d2, 14-d, 14,14'-d2, 15-d, 15,15'-d2) were synthesized, purified, and 1H NMR 1H-1H COSY, 1H-1H NOESY spectra were recorded.
The assignment shows high-field-shift of 1H signal adjacent to deuterium. Though the signals of di-substituted species were simple, mono-substitution made the signals complicatedly split and overlapped. These results showed the expected deuterium substitution was performed.
It is expected the frequency and coupling parameter among vibronic modes should change. We are trying to measure 1) ground state Raman spectroscopy to identify the spectral patterns 2) sub-picosecond stimulated Raman spectroscopy to find out the isotope effect on relaxation processes in the excited states.
